Java计算器源码

```.java
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Main extends JFrame implements ActionListener {
    private final JTextField tFormula;
    private final JTextField tResult;
    StringBuffer str;
    String operator;
    double x, y, result;
    private final JButton[] b = new JButton[12];
    private final JButton bDivision;
    private final JButton bBack;
    private final JButton bMultiplication;
    private final JButton bEmpty;
    private final JButton bAddition;
    private final JButton bSqrt;
    private final JButton bSubtraction;
    private final JButton bEquals;

public Main() {
        super("计算器");
        Container c = getContentPane();

tFormula = new JTextField(20);
        tFormula.setHorizontalAlignment(JTextField.LEFT);
        tFormula.setEditable(false);
        tResult = new JTextField(20);
        tResult.setHorizontalAlignment(JTextField.LEFT);
        tResult.setEditable(false);
        JLabel label = new JLabel("欢迎使用计算器 | by Rainbow_Cakjew");
        label.setForeground(Color.BLUE);
        str = new StringBuffer();

JPanel pInfo = new JPanel();
        pInfo.add(label);
        pInfo.add(tFormula);
        pInfo.add(tResult);
        pInfo.setLayout(new GridLayout(3, 1));
        for (int i = 0; i < 10; i++) {
            String s = "" + i;
            b[i] = new JButton(s);
            b[i].addActionListener(this);
        }
        b[10] = new JButton("%");
        b[11] = new JButton(".");
        bDivision = new JButton("/");
        bBack = new JButton("<-");
        bMultiplication = new JButton("*");
        bEmpty = new JButton("C");
        bAddition = new JButton("+");
        bSqrt = new JButton("Sqrt");
        bSubtraction = new JButton("-");
        bEquals = new JButton("=");
        for (int i = 0; i < 12; i++) {
            b[i].setForeground(Color.blue);
        }
        bDivision.setForeground(Color.red);
        bMultiplication.setForeground(Color.red);
        bAddition.setForeground(Color.red);
        bSubtraction.setForeground(Color.red);
        bBack.setForeground(Color.blue);
        bEmpty.setForeground(Color.blue);
        bSqrt.setForeground(Color.red);
        bEquals.setForeground(Color.blue);

JPanel pButton = new JPanel();
        pButton.add(bEmpty);
        pButton.add(bBack);
        pButton.add(bSqrt);
        pButton.add(bAddition);
        pButton.add(b[7]);
        pButton.add(b[8]);
        pButton.add(b[9]);
        pButton.add(bSubtraction);
        pButton.add(b[4]);
        pButton.add(b[5]);
        pButton.add(b[6]);
        pButton.add(bMultiplication);
        pButton.add(b[1]);
        pButton.add(b[2]);
        pButton.add(b[3]);
        pButton.add(bDivision);
        pButton.add(b[10]);
        pButton.add(b[0]);
        pButton.add(b[11]);
        pButton.add(bEquals);
        pButton.setLayout(new GridLayout(5, 4, 5, 5));

b[10].addActionListener(this);
        b[11].addActionListener(this);
        bDivision.addActionListener(this);
        bBack.addActionListener(this);
        bMultiplication.addActionListener(this);
        bEmpty.addActionListener(this);
        bAddition.addActionListener(this);
        bSqrt.addActionListener(this);
        bSubtraction.addActionListener(this);
        bEquals.addActionListener(this);

c.add(pInfo);
        c.add(pButton);
        c.setLayout(new FlowLayout());

setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setVisible(true);
        setResizable(false);
        setSize(300, 290);
        setLocation(100, 100);
    }

public static void main() {
        new Main();
    }

public void actionPerformed(ActionEvent e) {
        try {
            if (e.getSource() == bEmpty) {
                tFormula.setText("0");
                tResult.setText("0");
                str.setLength(0);
            } else if (e.getSource() == bBack) {
                if (str.length() > 1) {
                    str.deleteCharAt(str.length() - 1);
                    tFormula.setText(str.toString());
                } else {
                    tFormula.setText("0");
                    str.setLength(0);
                }
            } else if (e.getSource() == bSqrt) {
                x = Double.parseDouble((tFormula.getText().trim()));
                if (x < 0) {
                    tFormula.setText("数字格式异常");
                } else {
                    tResult.setText("" + Math.sqrt(x));
                }
                str.setLength(0);
            } else if (e.getSource() == b[10]) {
                x = Double.parseDouble((tFormula.getText()).trim());
                tResult.setText((x / 100) + "");
                str.setLength(0);
            } else if (e.getSource() == bEquals) {
                arithmetic(str.toString());
                str.setLength(0);
            } else if (e.getSource() == bAddition || e.getSource() == bSubtraction ||
                    e.getSource() == bMultiplication || e.getSource() == bDivision) {
                if (!str.isEmpty()) {
                    operator = e.getActionCommand();
                    x = Double.parseDouble(str.toString());
                    str.setLength(0);
                }
            } else if (e.getSource() == b[11]) {
                if (str.isEmpty()) {
                    str.append("0.");
                } else if (str.indexOf(".") == -1) {
                    str.append(".");
                }
                tFormula.setText(str.toString());
            } else {
                if (tFormula.getText().equals("0")) {
                    str.setLength(0);
                }
                str.append(e.getActionCommand());
                tFormula.setText(str.toString());
            }
        } catch (NumberFormatException ex) {
            tFormula.setText("数字格式错误");
            str.setLength(0);
        } catch (StringIndexOutOfBoundsException ex) {
            tFormula.setText("操作错误");
            str.setLength(0);
        }
    }

private void arithmetic(String s) {
        try {
            if (operator != null) {
                y = Double.parseDouble(s);
                switch (operator) {
                    case "+":
                        result = x + y;
                        break;
                    case "-":
                        result = x - y;
                        break;
                    case "*":
                        result = x * y;
                        break;
                    case "/":
                        if (y == 0) {
                            tResult.setText("除数不能为0");
                            return;
                        }
                        result = x / y;
                        break;
                }
                tResult.setText(String.valueOf(result));
                operator = null;
            }
        } catch (NumberFormatException ex) {
            tResult.setText("数字格式错误");
        }
    }
}
```