Cannot resolve "missing return statement error"

Question

Hi,
I have a small code where the following message is received when I am trying to compile it:
61: missing return statement
^
1 error
I cannot figure out what is the source of the error. I appreciate any help in advance. Thanks
THE FULL CODE:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class BuildSquare extends JApplet
implements ActionListener {
JLabel number1Label, resultLabel;
JTextField number1Field, resultField;
public void init()
Container container = getContentPane();
container.setLayout( new FlowLayout() );
number1Label = new JLabel("Enter an integer to represent the side of square" );
container.add(number1Label);
number1Field = new JTextField( 10 );
container.add( number1Field );
number1Field.addActionListener( this );
resultLabel = new JLabel ("The final square is: ");
container.add( resultLabel );
resultField = new JTextField( 15);
resultField.setEditable( false );
container.add( resultField);
public void actionPerformed( ActionEvent e )
     int a;
String Result;
     a = Integer.parseInt(number1Field.getText());
     showStatus("Calculating...");
     Result = DisplaySquare( a );
     showStatus( "Done");
     resultField.setText( Result );
public String DisplaySquare( int a )
String output = "";
for (int row = 1; row <= a; row ++) {
for (int column = 1; column <= a; column++ ) {
output += output + "* ";
output += "\n";
return output;
}

Answer 1

  public String DisplaySquare( int a )
   String output = "";
    for (int row = 1; row <= a; row ++)
       for (int column = 1; column <= a; column++ )
           output += output + "* ";
        } // end of "for  clumn"  
        output += "\n";
        return output;
    }  //end of "for   row"
    //mising return...............
  }  //end of public String DisplaySquare
} //end of public class BuildSquare