Java Programming Quiz

Which method is used to sort an array in Java?

• Collections.sort()

• Arrays.sort()

• array.sort()

• sort.array()

Which of the following is a valid declaration of a 2D array?

• int[][] arr = new int[2][3];

• int arr[][] = new int[2,3];

• int arr[] = new int[2][3];

• int arr[2][3];

What does this code print? int[][] matrix = { {1, 2}, {3, 4} }; System.out.println(matrix[1][1]);

• 2

• 3

• 4

• 1

Which loop is best for traversing arrays in Java?

• while

• do-while

• for

• goto

What is the output of the following code? String s1 = "Java"; String s2 = "Java"; System.out.println(s1 == s2);

• true

• false

• error

• null

Which method is used to compare two strings by ignoring case?

• equals()

• equalsIgnoreCase()

• compareTo()

• compareIgnoreCase()

Which of the following is used to concatenate two strings?

• concat()

• append()

• + operator

• All of the above

What is the result of this? String s = "abc"; s.concat("def"); System.out.println(s);

• abc

• abcdef

• defabc

• Compilation Error

Which class is thread-safe and mutable for strings?

• String

• StringBuilder

• StringBuffer

• ThreadString

What will this output? StringBuilder sb = new StringBuilder("Code"); sb.reverse(); System.out.println(sb);

• Code

• edoc

• edoC

• Cedo