什么类型的？

Question

import javax.swing.*;

     //*********Found********

import java.text.*;

public class Java_3

{

   public static void main( String args[] )

   {

     //*********Found********

      SimpleTime t = new  SimpleTime ( 12, 30, 19 );

     //*********Found********

      JOptionPane.showMessageDialog( null, t.buildString(),

         "Demonstrating the \"this\" Reference",

     //*********Found********

       JOptionPane.INFORMATION_MESSAGE  );

      System.exit( 0 );

   }

}

class SimpleTime {

   private int hour, minute, second;   

   public SimpleTime( int hour, int minute, int second )

   {

      this.hour = hour;

     //*********Found********

     this.minute = minute;

      this.second = second;

   }

   public String buildString()

   {

     //*********Found********

      return "this.toString(): " +this.toString()  +

             "\ntoString(): " + toString() +

             "\nthis (with implicit toString() call): " +

             this;

   }

   public String toString()

   {

      DecimalFormat twoDigits = new DecimalFormat( "00" );

      

      return twoDigits.format( this.hour ) + ":" +

             twoDigits.format( this.minute ) + ":" +

             twoDigits.format( this.second );

   }

}

这是java中那个内容的？为什么这么写？

Answer 1

java图形界面编程,那些代码只是显示格式化的数字.