importjava.awt.*;

　　importjava.awt.event.*;

　　importjavax.swing.*;

　　publicclass计算器extendsJFrameimplementsActionListener{

　　privatefinalString[]KEYS={"7","8","9","÷","sqrt","4","5","6",

　　"×","％","1","2","3","-","1/x","0","+/-",".","+","="};

　　privatefinalString[]COMMAND={"Backspace","CE","C"};

　　privatefinalString[]M={"","MC","MR","MS","M+"};

　　privateJButtonkeys[]=newJButton[KEYS.length];

　　privateJButtoncommands[]=newJButton[COMMAND.length];

　　privateJButtonm[]=newJButton[M.length];

　　privateJTextFieldresultText=newJTextField();

　　privatebooleanfirstDigit=true;

　　privatedoubleresultNum=0.0;

　　privateStringoperator="=";

　　staticdoublemr;//记忆的数字

　　privatebooleanoperateValidFlag=true;

　　JPanelpanel[]=newJPanel[4];

　　public计算器(){

　　super("计算器");

　　init();

　　setBackground(Color.LIGHT_GRAY);

　　setResizable(false);

　　setLocation(588,250);

　　setSize(378,214);

　　setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);//窗口不能直接关闭

　　setVisible(true);

　　addWindowListener(newWindowAdapter(){

　　publicvoidwindowClosing(WindowEvente){

　　if(JOptionPane.showConfirmDialog(null,"确定退出?","提示",2)==0){

　　System.exit(0);

　　}}});

　　}

　　privatevoidinit(){

　　setLayout(null);

　　for(inti=0;i