String Handling

String Handling

1) Which package does define String and StringBuffer classes?

Ans : java.lang package.

2) Which method can be used to obtain the length of the String?

Ans : length( ) method.

3) How do you concatenate Strings?

Ans : By using " + " operator.

4) Which method can be used to compare two strings for equality?

Ans : equals( ) method.

5) Which method can be used to perform a comparison between strings that ignores case differences?

Ans : equalsIgnoreCase( ) method.

6) What is the use of valueOf( ) method?

Ans : valueOf( ) method converts data from its internal format into a human-readable form.

7) What are the uses of toLowerCase( ) and toUpperCase( ) methods?

Ans : The method toLowerCase( ) converts all the characters in a string from uppercase to

lowercase.

The method toUpperCase( ) converts all the characters in a string from lowercase to

uppercase.

8) Which method can be used to find out the total allocated capacity of a StrinBuffer?

Ans : capacity( ) method.

9) Which method can be used to set the length of the buffer within a StringBuffer object?

Ans : setLength( ).

10) What is the difference between String and StringBuffer?

Ans : String objects are constants, whereas StringBuffer objects are not.

String class supports constant strings, whereas StringBuffer class supports growable, modifiable strings.

11) What are wrapper classes?

Ans : Wrapper classes are classes that allow primitive types to be accessed as objects.

12) Which of the following is not a wrapper class?

1.      String

2.      Integer

3.      Boolean

4.      Character

Ans : a.

13) What is the output of the following program?

public class Question {

public static void main(String args[]) {

String s1 = "abc";

String s2 = "def";

String s3 = s1.concat(s2.toUpperCase( ) );

System.out.println(s1+s2+s3);

}

}

1.      abcdefabcdef

2.      abcabcDEFDEF

3.      abcdefabcDEF

4.      None of the above

ANS : c.

14) Which of the following methods are methods of the String class?

1.      delete( )

2.      append( )

3.      reverse( )

4.      replace( )

Ans : d.

15) Which of the following methods cause the String object referenced by s to be changed?

1.      s.concat( )

2.      s.toUpperCase( )

3.      s.replace( )

4.      s.valueOf( )

Ans : a and b.

16) String is a wrapper class?

1.      True

2.      False

Ans : b.

17) If you run the code below, what gets printed out?

String s=new String("Bicycle");

int iBegin=1;

char iEnd=3;

System.out.println(s.substring(iBegin,iEnd));

1.      Bic

2.      ic

3.      icy

4.      error: no method matching substring(int,char)

Ans : b.

18) Given the following declarations

String s1=new String("Hello")

String s2=new String("there");

String s3=new String();

Which of the following are legal operations?

1.      s3=s1 + s2;

2.      s3=s1 - s2;

3.      s3=s1 & s2

4.      s3=s1 && s2

Ans : a.

19) Which of the following statements are true?

a)The String class is implemented as a char array, elements are addressed using the stringname[] convention

b) Strings are a primitive type in Java that overloads the + operator for concatenation

c) Strings are a primitive type in Java and the StringBuffer is used as the matching wrapper type

d) The size of a string can be retrieved using the length property.

Ans : b.