import javax.swing.JButton;

import java.awt.Graphics;

import java.awt.FlowLayout;

import javax.swing.JFrame;

import javax.swing.JTextField;

import java.awt.Color;

import java.awt.Container;

import java.awt.Dimension;

import javax.swing.JPanel;

import java.awt.Font;

import java.awt.event.ActionListener;

import java.awt.event.ActionEvent;

public class computer extends JFrame {

computer() {

super("简易计算器");

Font f = new Font("黑体", 30, 30);

JTextField jt1 = new JTextField(null);

JTextField jt2 = new JTextField(null);

jt1.setFont(f);

jt2.setFont(f);

jt1.setHorizontalAlignment(JTextField.RIGHT);

jt2.setHorizontalAlignment(JTextField.RIGHT);

Container c = getContentPane();

c.setLayout(new FlowLayout(FlowLayout.LEFT, 5, 5));

c.add(jt1);

c.add(jt2);

jt1.setPreferredSize(new Dimension(370, 70));

jt2.setPreferredSize(new Dimension(370, 75));

jt1.setEditable(false);

jt2.setEditable(false);

JButton jb[] = new JButton[16];

for (int j = 0; j < 16; j++) {

jb[j] = new JButton();

jb[j].setBackground(Color.WHITE);

jb[j].setFocusable(false);

jb[j].setPreferredSize(new Dimension(90, 90));

jb[j].setFont(f);

c.add(jb[j]);

}

this.setResizable(false);

//对各个按钮的名称赋值

jb[0].setText("+");

jb[1].setText("-");

jb[2].setText("*");

jb[3].setText("/");

jb[4].setText("1");

jb[5].setText("2");

jb[6].setText("3");

jb[7].setText("C");

jb[7].setBackground(Color.ORANGE);

jb[8].setText("4");

jb[9].setText("5");

jb[10].setText("6");

jb[11].setText("0");

jb[12].setText("7");

jb[13].setText("8");

jb[14].setText("9");

jb[15].setText("=");

JButton Button_num[] = {

jb[4],

jb[5],

jb[6],

jb[8],

jb[9],

jb[10],

jb[11],

jb[12],

jb[13],

jb[14]

};

for (int i = 0; i < Button_num.length; i++) {

Button_num[i].addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

JButton action_Button = (JButton) e.getSource();

jt2.setText(jt2.getText() + action_Button.getText());

}

});

}

for (int j = 0; j < 4; j++) {

jb[j].addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

String s = jt2.getText();

char ch = s.charAt(s.length() - 1);

if (ch == '+' || ch == '-' || ch == '*' || ch == '/')((JButton) e.getSource()).setEnabled(false);

else {

jt1.setText(jt2.getText());

jt2.setText(((JButton) e.getSource()).getText());

}

}

});

}

jb[7].addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

jt1.setText(null);

jt2.setText(null);

}

}

);

jb[15].addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

try {

String Calculate_String = jt1.getText() + jt2.getText();

int result = calculation.result(Calculate_String);

jt1.setText(null);

jt2.setText(Integer.toString(result));

} catch(ArithmeticException ex) {

jt1.setText(null);

jt2.setText("ERROR");

}

}

});

}

public static void main(String args[]) {

computer app = new computer();

app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

app.setSize(400, 580);

app.setVisible(true);

}

}

//再定义一个计算类calculation.java:

public class calculation {

calculation() {};

boolean is_operator(char ch) {

if (ch == '+' || ch == '-' || ch == '*' || ch == '/') return true;

else return false;

}

static int result(String s) {

String ch[] = {

"+",

"-",

"*",

"/"

};

int i = 0;

int index;

while (s.indexOf(ch[i]) == -1 && i < 4) {

i++;

}

if (i == 4) return - 1;

else index = s.indexOf(ch[i]);

String s1 = s.substring(0, index);

String s2 = s.substring(index + 1, s.length());

if (i == 0) return Integer.parseInt(s1) + Integer.parseInt(s2);

if (i == 1) return Integer.parseInt(s1) - Integer.parseInt(s2);

if (i == 2) return Integer.parseInt(s1) * Integer.parseInt(s2);

if (i == 3 && Integer.parseInt(s2) != 0) return Integer.parseInt(s1) / Integer.parseInt(s2);

else if (i == 3 && Integer.parseInt(s2) == 0) {

throw new ArithmeticException();

}

return - 1;

}

}