Core java Strings Interview Questions

Core java Strings Interview Questions

Strings

Q - Java provides two different string classes from which string objects can be instantiated. What

are they?

A - The two classes are:

     String

     StringBuffer

Q - The StringBuffer class is used for strings that are not allowed to change. The String class is

used for strings that are modified by the program: True or False. If false, explain why.

A - False. This statement is backwards. The String class is used for strings that are not allowed to change. The

StringBuffer class is used for strings that are modified by the program.

Q - While the contents of a String object cannot be modified, a reference to a String object can be

caused to point to a different String object: True or False. If false, explain why.

A - True.

Q - The use of the new operator is required for instantiation of objects of type String: True or

False? If false, explain your answer.

A - False. A String object can be instantiated using either of the following statements:

     String str1 = new String("String named str2");

   

     String str2 = "String named str1";

Q - The use of the new operator is required for instantiation of objects of type StringBuffer: True

or False? If false, explain your answer.

A - True.

Q - Provide a code fragment that illustrates how to instantiate an empty StringBuffer object of a

default length and then use a version of the append() method to put some data into the object.

A - See code fragment below:

     StringBuffer str5 = new StringBuffer();//accept default initial length

     str5.append("StringBuffer named str5");//modify length as needed

Q - Without specifying any explicit numeric values, provide a code fragment that will instantiate an

empty StringBuffer object of the correct initial length to contain the string "StringBuffer named str6"

and then store that string in the object.

A - See the following code fragment:

     StringBuffer str6 = new StringBuffer("StringBuffer named str6".length());

     str6.append("StringBuffer named str6");

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