evaluate your knowledge of Core Java

1. Which is the correct way to declare and store a character value to a variable?

Char ch="A"

Char ch='A'

Char [] ch='A'

Char []ch="A"

The correct way to declare and store a character value to a variable is by using the syntax "char ch='A'". In this case, the variable "ch" is declared as a character type and assigned the value 'A'.

Explanation

The correct way to declare and store a character value to a variable is by using the syntax "char ch='A'". In this case, the variable "ch" is declared as a character type and assigned the value 'A'.

2. Which of following is the correct declaration of main method?

Static public void main(String []a)

Void public static main()

Void public static main(String a[])

Public static main(String a[])

The correct declaration of the main method is "static public void main(String []a)". In Java, the main method is the entry point of a program and it must be declared as public, static, and void. The "public" keyword allows the method to be accessed from outside the class, the "static" keyword allows the method to be called without creating an instance of the class, and the "void" keyword indicates that the method does not return any value. The main method also takes a parameter of type String array, which allows command-line arguments to be passed to the program.

Explanation

The correct declaration of the main method is "static public void main(String []a)". In Java, the main method is the entry point of a program and it must be declared as public, static, and void. The "public" keyword allows the method to be accessed from outside the class, the "static" keyword allows the method to be called without creating an instance of the class, and the "void" keyword indicates that the method does not return any value. The main method also takes a parameter of type String array, which allows command-line arguments to be passed to the program.

3. Predict the output. abstract class cal {"\n" abstract public void sum(); abstract public void mul(); } public class calculation extens cal { int a=10,b=20,res=0; public void sum() { res=a+b; System.out.println("Result is : " +res); } public static void main(String []a) { calculation c=new calculation(); c.sum(); } }

Result is : 30

Result is : 0

Compile time error

Runtime error

Programe will generate compile time error.
calculation is not abstract and does not override abstract method "mul()"

Explanation

Programe will generate compile time error.
calculation is not abstract and does not override abstract method "mul()"

4. How execute a java program? Programe file name is "Example.java".

Java Example

Javac Example

Java Example.java

Javac Example.java

To execute a Java program with the file name "Example.java", the correct command is "java Example". This command runs the compiled bytecode file generated by the "javac" command. The "javac" command is used to compile the Java source code file into bytecode. Therefore, options "javac Example" and "javac Example.java" are incorrect as they are used for compilation, not execution. The correct command to execute the program is "java Example".

Explanation

To execute a Java program with the file name "Example.java", the correct command is "java Example". This command runs the compiled bytecode file generated by the "javac" command. The "javac" command is used to compile the Java source code file into bytecode. Therefore, options "javac Example" and "javac Example.java" are incorrect as they are used for compilation, not execution. The correct command to execute the program is "java Example".

5. While key words allow us to use class variable with our declaring the object of the class?

Final

Abstract

Interface

Static

The correct answer is "static". The keyword "static" allows us to use class variables without declaring an object of the class. Static variables are shared among all instances of a class and can be accessed directly using the class name.

Explanation

The correct answer is "static". The keyword "static" allows us to use class variables without declaring an object of the class. Static variables are shared among all instances of a class and can be accessed directly using the class name.

Evaluate Your Knowledge Of Core Java