SCJP Module-9 Question-9

The program given below will check your understanding NavigableSet, List, ArrayList and TreeSet of collection framework in Java.

 
 

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SCJP Module-9 Question-9

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The program given below will check your understanding NavigableSet, List, ArrayList and TreeSet of collection framework in Java.

Given below the sample code :

public class Check{
public static void main(String args[]){
ArrayList alist = new ArrayList();
ArrayList<String> listStr = alist;
ArrayList<StringBuffer> listBuf = alist;
listStr.add(0, "Welcome");
StringBuffer buff = listBuf.get(0);
System.out.println(buff.toString());
}
}

What will be the output of the following?

1. Welcome
2. Compile error
3. java.lang.ClassCastException
4. null

Answer

(3)

Explanation

'java.lang.String' cannot be cast to 'java.lang.StringBuffer'

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