calculater.java

这是一个java程序

import java.awt.*;
import java.awt.Graphics;
import java.awt.event.*;

public class Calculater extends Frame implements ActionListener
{
  private Button[]    buttons = new Button[19];//计算器上20个按钮
  private String[]    buttonText = { " 1 " , " 2 ", " 3 ", "  +  ", "  -  ",
                                      " 4 ", " 5 ", " 6 ", "  ×  ", "  /  ",
                                      " 7 ", " 8 ", " 9 ", "  ^  ", "exit",
                                      " C ", " 0 ", " . ", "        =        "};
  private TextField   result;       // 结果显示框
  private String      input = "";    // 用户的输入
  private Label       label;

  private Font        font,
                      buttonfont;
public Calculater(){
    super("计算器");

    //初始化颜色
    buttonfont = new Font( "Courier", Font.PLAIN, 12 );
    setBackground( Color.lightGray );

    result = new TextField(20);
    font = new Font( "宋体", Font.ITALIC, 10 );
    label = new Label( "结果" );
    label.setFont( font );
    result.setBackground( Color.white );
    setLayout( new FlowLayout() );

    //初始化按钮
    Panel mainPanel=new Panel();
    mainPanel.setLayout(new GridLayout(5,1));
    for ( int i = 0; i < 19; i++ ) {
       buttons[i] = new Button( buttonText[i] );
       buttons[i].setFont( buttonfont );
       buttons[i].addActionListener( this );
    }
    Panel panel1=new Panel();
    panel1.add( result );
    panel1.add( label );
    mainPanel.add(panel1);

    Panel panel2=new Panel();
    panel2.add(buttons[0]);
    panel2.add(buttons[1]);
    panel2.add(buttons[2]);
    panel2.add(new Label( "  " ));
    panel2.add(buttons[3]);
    panel2.add(buttons[4]);
    mainPanel.add(panel2);

    Panel panel3=new Panel();
    panel3.add(buttons[5]);
    panel3.add(buttons[6]);
    panel3.add(buttons[7]);
    panel3.add(new Label( "  " ));
    panel3.add(buttons[8]);
    panel3.add(buttons[9]);
    mainPanel.add(panel3);

    Panel panel4=new Panel();
    panel4.add(buttons[10]);
    panel4.add(buttons[11]);
    panel4.add(buttons[12]);
    panel4.add(new Label( "  " ));
    panel4.add(buttons[13]);
    panel4.add(buttons[14]);
    mainPanel.add(panel4);

    Panel panel5=new Panel();
    panel5.add(buttons[15]);
    panel5.add(buttons[16]);
    panel5.add(buttons[17]);
    panel5.add(new Label( "  " ));
    panel5.add(buttons[18]);
    mainPanel.add(panel5);

    add("Center",mainPanel);
    buttons[15].setForeground( Color.red );


    resize(235,210);
    show();
}

//==============================================================================
// 处理按钮被按下时的动作,进行相应的处理
//==============================================================================
public void actionPerformed( ActionEvent e )
{
   if ( e.getSource() == buttons[14] ) {
       dispose();
       System.exit(0);
     }
}
public void paint( Graphics g )
{
    //绘制边界
    g.drawRect( 0, 0, size().width - 1, size().height - 1 );
    g.drawLine( 0, 0, 0, size().height );
}
public static void main(String[] args){

     Calculater ca=new Calculater();
  }
} // end program