The Ultimate Java Test For Beginners
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Java runs on _______.
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Windows
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Unix/Linux
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Mac
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All of the Above
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This is the ultimate Java test for all those Java developer-wannabes who have just began practicing the programming language. It consists of over 93 questions of basically Core Java. So, if you are one of them and want to have a solid practice session to strengthen your hold on the concepts and methods, take it right now.
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- 2.
What is the difference between private and public functions?
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Public functions are free, you have to buy private ones
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Public functions are the only ones you can download
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Public functions can be used by anyone, private can only be used by other code in the class you are writing
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Public functions can’t be used
Correct Answer
A. Public functions can be used by anyone, private can only be used by other code in the class you are writingExplanation
Public functions are accessible to anyone and can be used by any code, whether it is within the same class or outside of it. On the other hand, private functions can only be accessed and used by other code within the same class. This encapsulation allows for better control and organization of code, as private functions are not accessible or usable by code outside of the class.Rate this question:
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- 3.
Choose the appropriate data type for this value: true
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Int
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Double
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String
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Boolean
Correct Answer
A. BooleanExplanation
The correct answer is boolean. The value "true" is a boolean value, which represents a logical true or false. It is used to store and manipulate boolean data in programming. The int data type is used for storing whole numbers, double is used for storing floating-point numbers, and String is used for storing textual data. However, in this case, the value "true" is specifically a boolean value.Rate this question:
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- 4.
Choose the appropriate data type for this value: 5.5
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Int
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Double
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Boolean
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String
Correct Answer
A. DoubleExplanation
The value 5.5 is a decimal number, so the appropriate data type to represent it is double.Rate this question:
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- 5.
Choose the best definition for a Class.
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A group of students in a class
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An object definition, containing the data and function elements necessary to create an object
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An action for a program
Correct Answer
A. An object definition, containing the data and function elements necessary to create an objectExplanation
A class is an object definition that contains the data and function elements necessary to create an object. In object-oriented programming, a class serves as a blueprint for creating objects, defining their properties (data) and behaviors (functions). It encapsulates the attributes and methods that an object will possess, allowing multiple objects to be created from the same class with their own unique data values.Rate this question:
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- 6.
Choose the appropriate data type for this value: 1
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Int
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Double
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String
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Boolean
Correct Answer
A. IntExplanation
The value "1" is a whole number and does not contain any decimal places. Therefore, the appropriate data type for this value would be "int" which stands for integer. Integers are used to represent whole numbers in programming languages.Rate this question:
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- 7.
Given the declaration : int [ ] ar = {1,2,3,4,5}; What is the value of ar[4]?
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2
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3
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4
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5
Correct Answer
A. 5Explanation
The given declaration initializes an integer array "ar" with the values {1,2,3,4,5}. In an array, the index starts from 0, so ar[4] refers to the fifth element of the array. Therefore, the value of ar[4] is 5.Rate this question:
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- 8.
Given the declaration int [ ] nums = {8, 12, 23, 4, 15}, what expression will display the first element in the array (ie the number 8)
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System.out.print("The number is : " + nums[0]);
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System.out.print("The number is : " + nums[1]);
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System.out.print("The number is : " + nums[8]);
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System.out.print("The number is : " + nums);
Correct Answer
A. System.out.print("The number is : " + nums[0]);Explanation
The correct answer is System.out.print("The number is : " + nums[0]); because nums[0] accesses the first element in the array nums, which is 8.Rate this question:
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- 9.
Given the declaration : int [ ] ar = {1,2,3,4,5}; What is the value of ar[3]?
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2
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3
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4
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5
Correct Answer
A. 4Explanation
The value of ar[3] is 4 because in the given declaration, the array ar contains the elements {1,2,3,4,5}. The index 3 refers to the fourth element in the array, which is 4.Rate this question:
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- 10.
The range of indices for an array always start at:
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Whatever programmer specifies
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1
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0
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Size of array
Correct Answer
A. 0Explanation
The range of indices for an array always starts at 0. In most programming languages, including popular ones like C, C++, Java, and Python, arrays are zero-indexed. This means that the first element of an array is accessed using the index 0. Therefore, the correct answer is 0.Rate this question:
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- 11.
Choose the best definition of an object
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A thing
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An instance of a class
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Something you wear
Correct Answer
A. An instance of a classExplanation
The correct answer is "an instance of a class." In object-oriented programming, an object is an instance of a class, which is a blueprint or template for creating objects. Objects have properties (attributes) and behaviors (methods) defined by the class, and they can interact with other objects. This definition accurately captures the concept of an object in the context of programming and distinguishes it from the other options provided.Rate this question:
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- 12.
What does GUI stand for?
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Graphical User Interface
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Gimme Ur Internet
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Grand User Interface
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Graphical Useful Interface
Correct Answer
A. Graphical User InterfaceExplanation
The correct answer is "Graphical User Interface". GUI stands for Graphical User Interface, which refers to the visual elements (such as icons, buttons, and windows) that allow users to interact with a computer system. It provides a user-friendly way to navigate and operate software applications, making it easier for users to perform tasks and access information.Rate this question:
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- 13.
Choose the appropriate data type for this value: A
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Int
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Double
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Char
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String
Correct Answer
A. CharExplanation
The appropriate data type for the value "A" is char. The value "A" represents a single character and can be stored in a char variable.Rate this question:
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- 14.
What is the proper way to declare a variable?
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VariableName variableType;
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VariableName;
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VariableType;
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VariableType variableName;
Correct Answer
A. VariableType variableName;Explanation
The proper way to declare a variable is by specifying the variable type followed by the variable name. This is the standard syntax used in most programming languages. By declaring the variable type first, the compiler or interpreter knows how much memory to allocate for the variable and what operations can be performed on it. The variable name is then used to refer to the value stored in the memory location allocated for the variable.Rate this question:
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- 15.
If you want your conditional to depend on two conditions BOTH being true, what is the proper notation to put between the two Boolean statements?
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&
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&&
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|
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||
Correct Answer
A. &&Explanation
The proper notation to put between two Boolean statements if you want your conditional to depend on both conditions being true is "&&".Rate this question:
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- 16.
What is a loop ?
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A new type of Applet.
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A segment of code to be run a specified amount of times
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A segment of code to be run infinite times
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A segment of code to be run once
Correct Answer
A. A segment of code to be run a specified amount of timesExplanation
A loop is a segment of code that is designed to be executed a specified number of times. It allows for the repetition of a certain set of instructions until a specific condition is met. By using loops, programmers can avoid writing the same code multiple times, making their programs more efficient and concise.Rate this question:
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- 17.
If classes Student, Staff and Faculty extend class Person, which one makes sense:
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Faculty[] faculties={new Person(), new Staff(), new Student()};
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Staff[] staff={new Person(), new Faculty(), new Student()};
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Person[] persons={new Faculty(), new Staff(), new Student()};
Correct Answer
A. Person[] persons={new Faculty(), new Staff(), new Student()};Explanation
The correct answer is "Person[] persons={new Faculty(), new Staff(), new Student()};". This makes sense because the class Person is the superclass, and both Staff and Faculty are subclasses of Person. Therefore, an array of type Person can hold objects of type Faculty, Staff, and Student, as they all inherit from Person.Rate this question:
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- 18.
What is an Applet?
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A Java program that does not run through a web browser
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A Java program that is run through a web browser
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An object-oriented programming language
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An interactive website
Correct Answer
A. A Java program that is run through a web browserExplanation
An applet is a Java program that is designed to be run through a web browser. Unlike standalone Java programs, applets are embedded within webpages and are executed on the client side. They are typically used to add interactive features to websites, such as animations, games, or multimedia content. Applets are written in the Java programming language and are executed within a Java Virtual Machine (JVM) that is embedded in the web browser. This allows the applet to be platform-independent and run on any device with a compatible web browser and JVM.Rate this question:
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- 19.
What is the main function of any variable?
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To add numbers together
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To keep track of data in the memory of the computer
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To print words on the screen
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To write Java codes
Correct Answer
A. To keep track of data in the memory of the computerExplanation
The main function of any variable is to keep track of data in the memory of the computer. Variables are used to store and manipulate data during the execution of a program. They allow us to save values that can be accessed and modified later in the program. By assigning values to variables, we can store and retrieve data, perform calculations, and make decisions based on the stored values. Variables play a crucial role in programming as they enable the storage and manipulation of data, making programs more dynamic and flexible.Rate this question:
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- 20.
What is an assignment statement?
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Adding a number to an int
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Assigning a multiplication
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Assigning a name to a variable
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Assigning a value to a variable
Correct Answer
A. Assigning a value to a variableExplanation
An assignment statement is used to assign a value to a variable. It is a fundamental concept in programming where a variable is given a specific value. This allows the variable to store and manipulate data throughout the program. In this context, the correct answer is "Assigning a value to a variable" because it accurately describes the purpose and functionality of an assignment statement.Rate this question:
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- 21.
Which one needs a web page to run
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A Java Application
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A Java Stand-Alone Application
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A Java Applet
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A Java Class
Correct Answer
A. A Java AppletExplanation
A Java Applet needs a web page to run because it is a small application that is designed to be embedded within a web page. It is executed within a web browser using a Java Virtual Machine (JVM) plugin. The web page provides the necessary environment and resources for the applet to run, such as HTML, CSS, and JavaScript. Applets are commonly used for interactive web content, such as games or multimedia applications.Rate this question:
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- 22.
Choose the appropriate data type for this field: kindOfBird
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String
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Int
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Char
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Double
Correct Answer
A. StringExplanation
example: kindOfBird = "Parrot"Rate this question:
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- 23.
What will be the value of “num” after the following statements? int num; num = (5+4); num = num / 9; num = 9;
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9
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1
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0
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Num
Correct Answer
A. 9Explanation
The value of "num" will be 9. The first statement assigns the value of 9 to "num" by evaluating the expression (5+4). The second statement divides the value of "num" (which is currently 9) by 9, resulting in 1. However, this value is not stored in "num" as the third statement assigns the value of 9 to "num" again, overriding the previous value. Therefore, the final value of "num" is 9.Rate this question:
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- 24.
Choose the appropriate data type for this field: numberOfEggs
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Double
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Char
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Boolean
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Int
Correct Answer
A. IntExplanation
The appropriate data type for the field "numberOfEggs" would be int. This is because the field is representing a count or quantity of eggs, which is typically a whole number and does not require decimal places. The int data type is used to store integer values, making it suitable for this scenario.Rate this question:
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- 25.
Synchronized is a keyword to tell a Thread to grab an Object lock before continuing execution.
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True
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False
Correct Answer
A. TrueExplanation
The explanation for the given answer is that the "synchronized" keyword in Java is used to ensure that only one thread can access a block of code or a method at a time. When a thread encounters a synchronized block, it grabs the object lock associated with that block before executing the code inside. This ensures that other threads cannot access the same block of code until the lock is released by the current thread. Therefore, the statement that synchronized is a keyword to tell a Thread to grab an Object lock before continuing execution is true.Rate this question:
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- 26.
Which of the following means that in order for the conditional to happen, either x must be less than 3 or y must be greater than or equal to 4?
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If ((x < 3) && (y > 4))
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If (x < 3 y >= 4)
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If ((x < 3) || (y > = 4))
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If ((x > 3) || (y < = 4))
Correct Answer
A. If ((x < 3) || (y > = 4))Explanation
The correct answer is if ((x < 3) || (y >= 4)). This means that the conditional will be true if either x is less than 3 or y is greater than or equal to 4. The "||" operator represents the logical OR, which means that if either condition is true, the entire expression will be true.Rate this question:
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- 27.
Primitive datatypes are allocated on a stack.
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True
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False
Correct Answer
A. TrueExplanation
Primitive datatypes are allocated on a stack because they are small and fixed in size. The stack is a region of memory that is used for local variables and function calls. When a primitive datatype is declared, it is allocated on the stack and its value is stored directly in that memory location. This allows for efficient memory management and quick access to the value. Additionally, since the stack is organized as a last-in-first-out data structure, allocating and deallocating memory for primitive datatypes is very simple and fast.Rate this question:
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- 28.
Can you compare a boolean to an integer?
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Yes
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No
Correct Answer
A. NoExplanation
A boolean is a data type that can only have two values: true or false. An integer, on the other hand, is a data type that represents whole numbers. Since a boolean and an integer are different data types, they cannot be directly compared. In most programming languages, attempting to compare a boolean to an integer would result in a type mismatch error.Rate this question:
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- 29.
The methods wait(), notify() and notifyAll() in Object need to be called from synchronized pieces of code.
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True
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False
Correct Answer
A. TrueExplanation
The methods wait(), notify(), and notifyAll() in the Object class need to be called from synchronized pieces of code because they are used for inter-thread communication and coordination. When a thread calls the wait() method, it releases the lock it holds and waits until another thread notifies it. Similarly, the notify() and notifyAll() methods are used to wake up waiting threads. Since these methods manipulate the internal state of the object, they should only be called from synchronized code to ensure thread safety and avoid potential race conditions.Rate this question:
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- 30.
The last value in an array called ar can be found at index:
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0
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1
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Ar.length
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Ar.length - 1
Correct Answer
A. Ar.length - 1Explanation
The last value in an array can be found at the index ar.length - 1 because array indices start at 0. So, if the length of the array is n, the indices will range from 0 to n-1. Therefore, the last value will be at the index ar.length - 1.Rate this question:
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- 31.
Choose the appropriate data type for this value: "volatile"
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Int
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String
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Double
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Boolean
Correct Answer
A. StringExplanation
The value "volatile" is a sequence of characters, which makes it a textual data. Therefore, the appropriate data type to represent this value would be a String.Rate this question:
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- 32.
What is the role of the constructor?
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Create an instance of a class (an object)
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Create names for methods
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To create some type of change in the state of an object
Correct Answer
A. Create an instance of a class (an object)Explanation
Constructors have one purpose in life: to create an instance of a class. This can also be called creating an object.Rate this question:
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- 33.
Choose the appropriate data type for this field: weightInKilos
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Char
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String
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Double
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Boolean
Correct Answer
A. DoubleExplanation
The field "weightInKilos" suggests that it is meant to store a numerical value representing weight. The data type "double" is appropriate for this field because it allows for decimal values, which are commonly used to represent weight. The data types "char" and "boolean" are not suitable for storing numerical values, and the data type "String" is not ideal for numerical calculations or comparisons.Rate this question:
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- 34.
Methods that are marked protected can be called in any subclass of that class.
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True
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False
Correct Answer
A. TrueExplanation
Protected methods in a class can be accessed by any subclass of that class. This means that if a method is marked as protected in a parent class, it can be called and used in any child class that inherits from the parent class. The protected access modifier allows for a level of encapsulation, where certain methods or variables are accessible only within the class and its subclasses. Therefore, the statement "Methods that are marked protected can be called in any subclass of that class" is true.Rate this question:
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- 35.
Choose the appropriate data type for this field: isSwimmer
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Double
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Boolean
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String
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Int
Correct Answer
A. BooleanExplanation
isSwimmer - yes or no (only two possible answers = boolean)Rate this question:
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- 36.
What loop will display each of the numbers in this array on a separate line: float [ ] nums= {1.1f, 2.2f, 3.3f};
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For (int i =0; i < 3; i++) System.out.println( nums[i]);
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For (i = 1; i
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For (i = 0; i
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For (i = 1; i < 3; i++) System.out.println(nums[i]);
Correct Answer
A. For (int i =0; i < 3; i++) System.out.println( nums[i]);Explanation
The correct answer is the first option: for (int i =0; i < 3; i++) System.out.println( nums[i]). This loop uses a for loop with an integer variable i initialized to 0 and incremented by 1 each iteration. The loop condition is i < 3, so the loop will run three times. Inside the loop, the System.out.println statement is used to print each element of the nums array on a separate line.Rate this question:
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- 37.
How to define a JButton with the caption test?
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JButton aButton('test');
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JButton aButton=new JButton("test");
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JButton aButton=new JButton('test');
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JButton("test") aButton;
Correct Answer
A. JButton aButton=new JButton("test");Explanation
The correct answer is JButton aButton=new JButton("test"). This is the correct way to define a JButton with the caption "test". The syntax follows the format of creating a new JButton object and assigning it to the variable "aButton", while passing the string "test" as the caption parameter in double quotes.Rate this question:
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- 38.
An abstract class can have non-abstract methods.
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True
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False
Correct Answer
A. TrueExplanation
An abstract class is a class that cannot be instantiated and is meant to be inherited by other classes. It can have both abstract and non-abstract methods. Abstract methods are declared without any implementation and must be overridden by the subclass, while non-abstract methods have a complete implementation and can be used as-is by the subclass. Therefore, it is true that an abstract class can have non-abstract methods.Rate this question:
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- 39.
What is the keyword used in java to create an object?
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This
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New
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Sync
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New()
Correct Answer
A. NewExplanation
In Java, the keyword "new" is used to create an object. This keyword is followed by the name of the class that we want to create an object of, and it allocates memory for the object and returns a reference to it. By using the "new" keyword, we can instantiate an object of a class and access its properties and methods.Rate this question:
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- 40.
What's the difference between an Applet and an application?
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None of the above.
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Applets are run over the web.
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Applets can paint words, applications cannot.
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An application is only available on Windows
Correct Answer
A. Applets are run over the web.Explanation
Applets are a type of software program that can be run within a web browser. They are typically used to enhance the functionality of a website by providing interactive features. On the other hand, applications are standalone software programs that are installed on a computer and can be run independently of a web browser. Therefore, the main difference between an applet and an application is that applets are specifically designed to be run over the web, while applications are not limited to web-based environments.Rate this question:
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- 41.
What is displayed from the following statements? int [ ] nums = {1,2,3,4,5,6}; System.out.println((nums[1] + nums[3]));
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6
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2+4
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1+3
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4
Correct Answer
A. 6Explanation
The code initializes an integer array named "nums" with the values {1, 2, 3, 4, 5, 6}. The statement "System.out.println((nums[1] + nums[3]));" prints the sum of the elements at index 1 and index 3 of the array, which are 2 and 4 respectively. Therefore, the output will be 6.Rate this question:
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- 42.
The following prototype shows that a Cylinder subclass is derived from a superclass called Circle
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Class Circle extends Cylinder
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Class Cylinder derived Circle
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Class Cylinder extends Circle
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Class Circle derived Cylinder
Correct Answer
A. Class Cylinder extends CircleExplanation
The correct answer is "class Cylinder extends Circle". This is because the keyword "extends" is used to indicate that the class Cylinder is derived from the superclass Circle. In object-oriented programming, inheritance allows a subclass to inherit the properties and methods of its superclass, and by extending Circle, the Cylinder subclass can access and use the attributes and behaviors defined in the Circle class.Rate this question:
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- 43.
With inheritance, a derived subclass object can directly access any
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Public or private superclass member
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Private superclass member
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Public superclass member (and protected subclass members if it's in the same package)
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Protected, public or private superclass member
Correct Answer
A. Public superclass member (and protected subclass members if it's in the same package)Explanation
Inheritance allows a derived subclass object to directly access any public superclass member. Additionally, if the subclass is in the same package as the superclass, it can also access protected subclass members. However, private superclass members cannot be accessed by the subclass object. Therefore, the correct answer is public superclass member (and protected subclass members if it's in the same package).Rate this question:
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- 44.
Inner classes can be defined within methods.
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True
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False
Correct Answer
A. TrueExplanation
Inner classes can be defined within methods. This statement is true. In Java, inner classes are classes that are defined within another class. They can also be defined within methods. When an inner class is defined within a method, it is called a local inner class. Local inner classes have access to the variables and methods of the enclosing method, which can be useful in certain situations. However, it is important to note that local inner classes can only be accessed within the method in which they are defined.Rate this question:
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- 45.
If we declare int [ ] ar = {1,2,3,4,5,6}; The size of array ar is:
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0
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5
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6
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7
Correct Answer
A. 6Explanation
The size of the array "ar" is 6. This is because the array has 6 elements inside the curly braces {1, 2, 3, 4, 5, 6}. Each element takes up one slot in the array, so the size of the array is equal to the number of elements it contains, which in this case is 6.Rate this question:
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- 46.
Java keywords are written in lowercase as well as uppercase.
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True
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False
Correct Answer
A. FalseExplanation
Java keywords are written in lowercase only. In Java, keywords are predefined reserved words that have specific meanings and cannot be used as identifiers (variable names, method names, etc.). These keywords are case-sensitive, meaning that using uppercase letters in keywords will result in a compilation error. Therefore, the statement that Java keywords can be written in both lowercase and uppercase is false.Rate this question:
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- 47.
An object could be ...
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Anything
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An algorithm
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A data container
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A program
Correct Answer
A. AnythingExplanation
The given correct answer for this question is "anything". This is because the question states that an object could be anything, including an algorithm, a data container, or a program. The term "anything" encompasses all possibilities and allows for flexibility in the definition of an object.Rate this question:
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- 48.
The most common use of an array is to:
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Perform for loop on array
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Perform different operations on each element in array
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Perform the same operation on all elements in array
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Perform while loop on array
Correct Answer
A. Perform the same operation on all elements in arrayExplanation
The most common use of an array is to perform the same operation on all elements in the array. Arrays allow for efficient storage and retrieval of multiple values of the same data type. By applying a single operation to each element in the array, tasks such as calculations, transformations, or comparisons can be easily performed on a large set of data. This allows for concise and efficient coding, as the same code can be applied to each element in the array without the need for repetitive code or manual iteration.Rate this question:
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- 49.
A class is...
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An object
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An executable piece of code
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An abstract definition of an object
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A variable
Correct Answer
A. An abstract definition of an objectExplanation
A class is an abstract definition of an object because it represents the blueprint or template for creating objects of that class. It defines the properties (attributes) and behaviors (methods) that the objects of that class will have. The class itself is not an object, but rather a description or definition of what an object of that class should be like. Objects are instances of classes, created based on the class definition, and they have their own unique state and behavior.Rate this question:
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Mar 21, 2025Quiz Edited by
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Apr 22, 2012Quiz Created by
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