24. The startswith () Method



Answer:
  • Can an object reference variable exist without referring to an object?
    • Yes, a reference variable can be declared without initialization:
      String myString;
    • Also, a reference can be set to null.
  • Can an object exist without an object reference variable that refers to it?
    • Yes, as seen in the previous example. Such objects are temporary.
The startsWith() Method

    



    
        

        

        

            
                
class PrefixTest
{
  public static void main ( String args[] )
  {
     String burns = "My love is like a red, red rose.";

     if ( burns.startsWith( "My love" ) )
       System.out.println( "Prefix 1 matches." );
     else
       System.out.println( "Prefix 1 fails." );

     if ( burns.startsWith( "my love" ) )
       System.out.println( "Prefix 2 matches." );
     else
       System.out.println( "Prefix 2 fails." );

     if ( burns.startsWith( "  My love" ) )
       System.out.println( "Prefix 3 matches." );
     else
       System.out.println( "Prefix 3 fails." );

     if ( burns.startsWith( "  My love".trim() ) )
       System.out.println( "Prefix 4 matches." );
     else
       System.out.println( "Prefix 4 fails." );
  }
}

            		
        

    







    









    





    

    

    

    

    

        

    

    

        

        

    





    

        

            

            

            

                

            

        

    





Here is another method of the String class:
    public boolean startsWith(String  prefix); 

The startsWith() method tests if one String is the prefix of another. This is frequently needed in programs. (Although this example is too short to show a real-world situation.)
Notice how trim() is used in the last if statement.




    

        

    




Question 24:
What does the program write?