Java Programming Quiz in String

What will be the output of the following code? String s1 = "Java"; String s2 = "Java"; String s3 = new String("Java"); System.out.println(s1 == s2); System.out.println(s1 == s3);

• true, true

• true, false

• false, true

• false, false

What will be printed? String s = "abc"; s.concat("def"); System.out.println(s);

• abc

• abcdef

• def

• Compilation error

Choose the correct statement:

• StringBuilder is synchronized.

• StringBuffer is not synchronized.

• StringBuilder is faster but not thread-safe.

• String is mutable.

Output? StringBuilder sb = new StringBuilder("123"); sb.reverse(); System.out.println(sb);

• 123

• 321

• Error

• 1 2 3

What will this print? String str = "hello"; str.toUpperCase(); System.out.println(str);

• HELLO

• hello

• Error

• null

Which of these methods is NOT available in StringBuilder?

• append()

• reverse()

• charAt()

• trim()

Which creates a new object each time it's modified?

• String

• StringBuffer

• StringBuilder

• All of the above

Output? String s = "abc"; s = s + s.length(); System.out.println(s);

• abc3

• abc

• abcabc

• 3abc

Output of: StringBuffer sb = new StringBuffer("Java"); sb.setCharAt(0, 'L'); System.out.println(sb);

• Lava

• Java

• Error

• Ljava

What is the capacity of this? StringBuffer sb = new StringBuffer(); System.out.println(sb.capacity());

• 0

• 16

• -1

• 1