Which of the following methods belong to the String class ?

1. length()
2. compareTo()
3. equals()
4. substring()
5. All of these
6. None of them

Given the code

String s1 = "yes" ;
String s2 = "yes" ;
String s3 = new String(s1) ;

Which of the following would equate to False ?

1. s1 == s2
2. s3 == s1
3. s1.equals(s2)
4. s3.equals(s1)

Given the code :

String s = new String("abc");

Which of the following calls are invalid ?

1. s.trim( )
2. s.replace('a', 'A')
3. s.substring(3)
4. s.toUpperCase( )
5. s.setCharAt(1, 'A')

Which of these class is superclass of String and StringBuffer class?

1. java.util
2. java.lang
3. ArrayList
4. None of the mentioned