import java.awt.*;
import java.awt.event.*;
public class Calculator extends JFrame implements ActionListener{
private static final long serialVersionUID = 8199443193151152362L;
private JButton bto_s=new JButton("sqrt"),bto_zf=new JButton("+/-"),bto_ce=new JButton("CE"),bto_c=new JButton("C"),bto_7=new JButton("7"),
bto_8=new JButton("8"),bto_9=new JButton("9"),bto_chu=new JButton("/"),bto_4=new JButton("4"),bto_5=new JButton("5"),
bto_6=new JButton("6"),bto_cheng=new JButton("*"),bto_1=new JButton("1"),bto_2=new JButton("2"),bto_3=new JButton("3"),
bto_jian=new JButton("-"),bto_0=new JButton("0"),bto_dian=new JButton("."),bto_deng=new JButton("="),bto_jia=new JButton("+");
JButton button[]={bto_s,bto_zf,bto_ce,bto_c,bto_7,bto_8,bto_9,bto_chu,bto_4,bto_5,bto_6,bto_cheng,bto_1,bto_2,bto_3,bto_jian,
bto_0,bto_dian,bto_deng,bto_jia};
private JTextField text_double;// = new JTextField("0");
private String operator = "="; //當前運算的運算符
private boolean firstDigit = true; // 標誌用戶按的是否是整個表達式的第壹個數字,或者是運算符後的第壹個數字
private double resultNum = 0.0; // 計算的中間結果
private boolean operateValidFlag = true; //判斷操作是否合法
public Calculator()
{
super("Calculator");
this.setBounds(300, 300, 300, 300);
this.setResizable(false);
this.setBackground(Color.orange);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.getContentPane().setLayout(new BorderLayout());//設置布局
text_double=new JTextField("0",20);//設置文本區
text_double.setHorizontalAlignment(JTextField.RIGHT);//設置水平對齊方式未右對齊
this.getContentPane().add(text_double,BorderLayout.NORTH);//將文本區添加到Content北部
JPanel panel=new JPanel(new GridLayout(5,4));//在內容窗口添加壹個網格布局
this.getContentPane().add(panel);//添加panel面板
for(int i=0;i<button.length;i++)//在面板上添加按鈕
panel.add(button[i]);
for(int i=0;i<button.length;i++)
button[i].addActionListener(this);//為按鈕註冊
text_double.setEditable(false);//文本框不可編輯
text_double.addActionListener(this);//
this.setVisible(true);
}
public void actionPerformed(ActionEvent e)//
{
String c= e.getActionCommand();//返回與此動作相關的命令字符串。
System.out.println("##########command is "+c);
if(c.equals("C")){
handleC(); //用戶按了“C”鍵
}
else if (c.equals("CE")) // 用戶按了"CE"鍵
{
text_double.setText("0");
}
else if ("0123456789.".indexOf(c) >= 0) // 用戶按了數字鍵或者小數點鍵
{
handleNumber(c); // handlezero(zero);
} else //用戶按了運算符鍵
{
handleOperator(c);
}
}
private void handleC() // 初始化計算器的各種值
{
text_double.setText("0");
firstDigit = true;
operator = "=";
}
private void handleNumber(String button) {
if (firstDigit)//輸入的第壹個數字
{
text_double.setText(button);
} else if ((button.equals(".")) && (text_double.getText().indexOf(".") < 0))//輸入的是小數點，並且之前沒有小數點，則將小數點附在結果文本框的後面
//如果字符串參數作為壹個子字符串在此對象中出現，則返回第壹個這種子字符串的第壹個字符的索引；如果它不作為壹個子字符串出現，則返回 -1
{
text_double.setText(text_double.getText() + ".");
} else if (!button.equals("."))// 如果輸入的不是小數點，則將數字附在結果文本框的後面
{
text_double.setText(text_double.getText() + button);
}
// 以後輸入的肯定不是第壹個數字了
firstDigit = false;
}
private void handleOperator(String button) {
if (operator.equals("/")) {
// 除法運算
// 如果當前結果文本框中的值等於0
if (getNumberFromText() == 0.0){
// 操作不合法
operateValidFlag = false;
text_double.setText("除數不能為零");
} else {
resultNum /= getNumberFromText();
}
} else if (operator.equals("+")){
// 加法運算
resultNum += getNumberFromText();
} else if (operator.equals("-")){
// 減法運算
resultNum -= getNumberFromText();
} else if (operator.equals("*")){
// 乘法運算
resultNum *= getNumberFromText();
} else if (operator.equals("sqrt")) {
// 平方根運算
if(getNumberFromText()<0){
operateValidFlag = false;
text_double.setText("被開方數不能為負數");}
else
resultNum = Math.sqrt(resultNum);
}
else if (operator.equals("+/-")){
// 正數負數運算
resultNum = resultNum * (-1);
} else if (operator.equals("=")){
// 賦值運算
resultNum = getNumberFromText();
}
if (operateValidFlag) {
// 雙精度浮點數的運算
long t1;
double t2;
t1 = (long) resultNum;
t2 = resultNum - t1;
if (t2 == 0) {
text_double.setText(String.valueOf(t1));
} else {
text_double.setText(String.valueOf(resultNum));
}
}
operator = button; //運算符等於用戶按的按鈕
firstDigit = true;
operateValidFlag = true;
}
private double getNumberFromText() //從結果的文本框獲取數字
{
double result = 0;
try {
result = Double.valueOf(text_double.getText()).doubleValue(); // ValueOf()返回表示指定的 double 值的 Double 實例
} catch (NumberFormatException e){
}
return result;
}
public static void main(final String[] args) {
new Calculator();
}
}