Java Quiz For Job Interview Questions
Java Quiz for Job Interview
- 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
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