JAVA实现四则运算的简单计算器

开发环境eclipse java neon.

今天用JAVA的swing界面程序设计制作了一个四则运算的简易计算器.代码以及截图如下:

computer.java:

/////////////////////////////////////////
//
//开发者：
//
//简介：实现四则运算的简易计算器
//
////////////////////////////////////////
/*
*用swing图形用户界面实现计算器的设计
*同时练习在线文档注释的使用方法
*
* @author linruier
* @version 1.0
* @since J2SE1.8
*/
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;
    }

}

最后运行就可以实现一个十分简洁的小计算器：