Java Quiz For Job Interview

25 Questions | By Vijayaprakash | Last updated: Mar 20, 2022 | Total Attempts: 283

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Java Quiz for Job Interview

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1.

Public class Swap { public static void swapStrings(String x, String y){ String temp = x; x=y; y=temp; } public static void main(String[] args) { String a = "1"; String b = "2"; swapStrings(a, b); System.out.println("a="+a+" ,b="+b); }} What will be the output when executing this main?
- A.
  
  An exception will be thrown
- B.
  
  “a=2 ,b=1”
- C.
  
  “a=1 ,b=2” because strings are immutable
- D.
  
  “a=1 ,b=2” because Java passes parameters by value
2.

Class Parent{ protected void x(){} public void y(){}}public class Child extends Parent{ public void x(){} protected void y(){}}
- A.
  
  It compiles successfully
- B.
  
  Compilation error – x can’t have its visibility increased
- C.
  
  Compilation error – y can not have its visibility reduced
- D.
  
  Compilation error – neither x nor y can have their visibility changed
3.

Following code will result in: int a = 3.5;
- A.
  
  Compilation error
- B.
  
  Runtime error
- C.
  
  A being 3.5
- D.
  
  A being 3
4.

Following code will result in: int a1 = 5; double a2 = (float) a1;
- A.
  
  Compilation error
- B.
  
  Runtime error
- C.
  
  No errors
5.

Following code will result in: class A { int b = 1; public static void main(String[] args) { System.out.println("b is " + b); }}
- A.
  
  Compilation error
- B.
  
  Runtime Error
- C.
  
  Runtime Exception
- D.
  
  B is 1
6.

Following code will result in: class A { public static void main(String[] args) { B b = new A(); }}class B extends A {}
- A.
  
  Compile error
- B.
  
  Runtime Exception
- C.
  
  No error
7.

Following code will result in: class A { public static void main(String[] args) { A a = new B(); }}class B extends A {}
- A.
  
  Compiler error
- B.
  
  Runtime Exception
- C.
  
  No errors
8.

Methods that are marked protected can be called in any subclass of that class
- A.
  
  True
- B.
  
  False
9.

An abstract class can have non-abstract methods.
- A.
  
  True
- B.
  
  False
10.

What is an instanceof
- A.
  
  A method in object
- B.
  
  An operator and keyword
11.

Can you compare a boolean to an integer?
- A.
  
  True
- B.
  
  False
12.

If class A implements an interface does it need to implement all methods of that interface?
- A.
  
  Yes, always
- B.
  
  No, not when A is abstract
13.

Integer a = new Integer(2); Integer b = new Integer(2); What happens when you do if (a==b)?
- A.
  
  Compiler error
- B.
  
  Runtime Exception
- C.
  
  True
- D.
  
  False
14.

Synchronized is a keyword to tell a Thread to grab an Object lock before continuing execution.
- A.
  
  True
- B.
  
  False
15.

Which ones does not extend java.lang.Number(you can make multiple choices)
- A.
  
  Integer
- B.
  
  Boolean
- C.
  
  Character
- D.
  
  Long
- E.
  
  Short
16.

Which JDBC method is used to execute any SQL statement with a "SELECT" clause, that return the result of the query as a result set.
- A.
  
  ExecuteUpdate()
- B.
  
  ExecuteQuery()
- C.
  
  Execute()
17.

Which JDBC method is used to execute INSERT, DELETE, UPDATE , and other SQL DDL such as CREATE, DROP TABLE.
- A.
  
  ExecuteUpdate()
- B.
  
  ExecuteQuery()
- C.
  
  Execute()
18.

Which JDBC method is used for retrieving a string value (SQL type VARCHAR) and assigning into java String object.
- A.
  
  GetVarchar()
- B.
  
  GetObject()
- C.
  
  GetString()
19.

This method is used for retrieving the value from current row as object.
- A.
  
  GetRow()
- B.
  
  GetObject()
- C.
  
  GetString()
20.

The Connection.prepareStatement() method accepts a SQL query and returns a...
- A.
  
  PreparedStatement object
- B.
  
  CallableStatement object
- C.
  
  PrepareCall method
21.

This method returns an integer value indicating a row count.
- A.
  
  ExecuteQuery()
- B.
  
  ExecuteUpdate()
- C.
  
  Execute()
22.

Consider the following classpublic class Test implements Runnable{ public void run() { }}Creating an instance of this class and calling its run() method will spawn a new thread.
- A.
  
  True
- B.
  
  False
23.

What is the result of attempting to compile and run the following code?public class Test { public static void main(String[] args){ Integer a = new Integer(4); Integer b = new Integer(8); Set hs = new HashSet(); hs.add(a); hs.add(b); hs.add(a); System.out.println(hs.size()); }}
- A.
  
  It prints: 2
- B.
  
  It prints: 3
24.

What is the result of attempting to compile and run the following code?public class Test { public static void main(String[] args){ Integer a = new Integer(4); Integer b = new Integer(8); Integer c = new Integer(4); Set hs = new HashSet(); hs.add(a); hs.add(b); hs.add(c); System.out.println(hs.size()); }}
- A.
  
  It prints: 2
- B.
  
  It prints: 3
25.

Class Figure { public void print() { System.out.println("FIGURE"); }}class Triangle extends Figure { public void print() { System.out.println("TRIANGLE"); }}public class Test { public static void main(String[] args) { Figure f1 = new Figure(); f1.print(); Figure f2 = new Triangle(); f2.print(); Triangle t = new Triangle(); t.print(); }}What will this program print out?
- A.
  
  FIGURE FIGURE FIGURE
- B.
  
  FIGURE FIGURE TRIANGLE
- C.
  
  FIGURE TRIANGLE TRIANGLE