Data Types in Java - MCQ Questions with Answers - Core Java Quiz

Questions
1 Which of the following is not an valid declaration of an array?
A int [ ] a = new int [3];
B int a [ ] [ ] = new int [3] [3]
C int [ ] [ ] a = new int [3] [ ];
D int [ ] [ ] a = new int [ ] [3];

Answer: Option [D]

In multidimensional array rows cannot left blank.

2 String.ValueOf('r').concat("def").concat(String.ValueOf('2'))
A 0
B 1
C 3
D 4

Answer: Option [B]

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3 Which of the following is correct statement?
A Boolean true value is 1 and false value is 0
B Every private class has a wrapper class
C Constant identifier precede with a reserved word final
D System.out.println() method also flushes the buffer

Answer: Option [C]

Constants are not directly supported by Java. The reserved 'Final' is used to declare constant.

4 Size of an integer can be
A -231 to 231-1
B 0 to -216
C -28 to 28-1
D -215 to 215-1

Answer: Option [A]

Int takes 4 bytes i.e. 32bits. 1 bit is reserved to store sign.

5 For which of the following data types the ValueOf() method is NOT overloaded in the string class?
A Float
B Boolean
C Object
D None of these

Answer: Option [D]

For all Java built in types ValueOf() method is overloaded within the String. valueOf() method returns the string representation of the corresponding arguments value.

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