return true; 

specifies that the action method is to return a value of true.

• This tells the applet that the event (the user pressing enter) has been processed.
• The Addition applet has introduced some new objects and methods:

Applet

• void add( GUI component ) // put GUI component on the applet
• boolean action( Event, Object)
• void init()
• void showStatus( String ) // display String on status bar

Label

• void Label( String ) // constructs a label
• void setText( String )

TextField

• void TextField( int ) // construct a TextField that is int characters wide

Conversion "methods" (I'll explain later what they really are)

• int Integer.parseInt( String )
• String Integer.toString( int )