用Java写一个计算器
1、调用Javax.swing.*（图形化）
import javax.swing.*;2、初始化它的外形
class WindowOperation extends JFrame {
JMenuBar menuBar; //菜单条
JMenu menu1, menu2, menu3; //菜单
JPanel panel; //按钮面板
JTextArea textArea; //文本区
JButton[][] button = new JButton[6][5]; //30个按钮
String Mem = "0"; //存储区的值
WindowOperation() {
init();
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
validate();
}
3、设置字体、计算符号等功能
void init() {
setBounds(300, 50, 640, 700); //窗口大小
setTitle("calculator"); //窗口名称
setLayout(new BorderLayout()); //布局样式
LineBorder border = new LineBorder(Color.LIGHT_GRAY, 6, true);//文本区域边框设置
textArea = new JTextArea(2, 10); //计算区域
textArea.setFont(new Font("Calibre", Font.PLAIN, 60)); //设置字体、样式、大小
textArea.setBorder(border);
String [][] str = {
{"Mc", "Mr", "Ms", "M+", "M-"},
{"<—", "CE", "C", "±", "√"},
{"7", "8", "9", "/", "%"},
{"4", "5", "6", "*", "1/x"},
{"1", "2", "3", "-", "^2"},
{"00", "0", ".", "+", "="}
};
panel = new JPanel();
panel.setLayout(new GridLayout(6, 5));
for (int i = 0; i < 6; i++) { //插入各个功能、数字按钮
for (int j = 0; j < 5; j++) {
button[i][j] = new JButton(str[i][j]);
button[i][j].setFont(new Font("黑体", Font.BOLD, 30)); //设置按钮字体、样式、大小
panel.add(button[i][j]);
}
}
add(textArea, BorderLayout.NORTH);
add(panel);
menu1 = new JMenu(" 查看(C) ");
menu1.setFont(new Font("楷体", Font.PLAIN, 20)); //设置字体、样式、大小
menu2 = new JMenu(" 编辑(E) ");
menu2.setFont(new Font("楷体",Font.PLAIN, 20));
menu3 = new JMenu(" 帮助(H) ");
menu3.setFont(new Font("楷体", Font.PLAIN, 20));
menuBar = new JMenuBar();
menuBar.add(menu1);
menuBar.add(menu2);
menuBar.add(menu3);
setJMenuBar(menuBar);
Event();
}
4、设置监视器
public void Event() { //对各种事件注册监视器
for (int i = 2; i < 6; i++) {
for (int j = 0; j < 5; j++) {
//除了”=“和”MC“等功能键，全部设置自己的监视器
if(i != 5 || j != 4)
button[i][j].addActionListener(new TextListener(button[i][j], textArea));
}
}
//清楚存储区数值
button[0][0].addActionListener((e -> Mem = "0"));
//显示存储区数值字符串
button[0][1].addActionListener(e -> textArea.setText(Mem));
//存储结果
button[0][2].addActionListener(e -> {
Mem = textArea.getText();
Mem = Mem.substring(Mem.indexOf('\n')+1); //去掉第一行字符串，只留下结果
});
//当前文本区的值与存储区的值相加
button[0][3].addActionListener(e -> {
double x1, x2;
x1 = Double.parseDouble(Mem);
x2 = Double.parseDouble(textArea.getText());
Mem = "" + (x1 + x2);
});
button[0][4].addActionListener(e -> {
double x1, x2;
x1 = Double.parseDouble(Mem);
x2 = Double.parseDouble(textArea.getText());
Mem = "" + (x2 - x1);
});
button[1][0].addActionListener(new BackListener(textArea));
button[1][1].addActionListener(new BackListener(textArea));
button[1][2].addActionListener(new ClearListener(textArea));
button[1][3].addActionListener(new TextListener(button[1][3], textArea));
button[1][4].addActionListener(new TextListener(button[1][4], textArea));
button[5][4].addActionListener(new ResultListener(textArea));
}
}
5、传入文本，进行计算
class ResultListener implements ActionListener {
JTextArea textArea;
String str; //用来保存文本区域的字符串；
public ResultListener(JTextArea textArea1) { //将文本区传入
textArea = textArea1;
}
public void actionPerformed(ActionEvent e) {
textArea.setText(textArea.getText() + "="); //获取文本内容
str = textArea.getText();
if (str.contains("+")) { //如果字符串中包含“+”，做加法运算
String str1 = str.substring(0, str.indexOf('+')); //获取加数
String str2 = str.substring(str.indexOf('+') + 1, str.indexOf('=')); //获取被加数
double x1 = Double.parseDouble(str1); //转化为double类型
double x2 = Double.parseDouble(str2);
textArea.setText(str + "\n" + (x1 + x2));
}
else if (str.contains("*")) { //乘法运算
String str1 = str.substring(0, str.indexOf('*'));
String str2 = str.substring(str.indexOf('*') + 1, str.indexOf('='));
double x1 = Double.parseDouble(str1);
double x2 = Double.parseDouble(str2);
textArea.setText(str + "\n" + x1 * x2);
}
else if(str.contains("1/x")) { //倒数运算
String str1 = str.substring(0, str.indexOf("1/x"));
double x1 = Double.parseDouble(str1);
if(x1 == 0) textArea.setText(str + "\n" + "不能求倒数");
else textArea.setText(str + "\n" + 1/x1);
}
else if (str.contains("/")) { //除法运算
String str1 = str.substring(0, str.indexOf('/'));
String str2 = str.substring(str.indexOf('/') + 1, str.indexOf('='));
double x1 = Double.parseDouble(str1);
double x2 = Double.parseDouble(str2);
if (x2 == 0) textArea.setText(str + "\n" + "不能除以0");
else textArea.setText(str + "\n" + x1 / x2);
}
else if (str.contains("^2")) { //平方运算
String str1 = str.substring(0, str.indexOf('^'));
double x = Double.parseDouble(str1);
textArea.setText(str + "\n" + x * x);
}
else if (str.contains("√")) { //开方运算
String str1 = str.substring(str.indexOf('√') + 1, str.indexOf('='));
double x = Double.parseDouble(str1);
textArea.setText(str + "\n" + Math.sqrt(x));
}
else if (str.contains("±")) { //加减运算
String str1 = str.substring(0, str.indexOf('±'));
String str2 = str.substring(str.indexOf('±') + 1, str.indexOf('='));
double x1 = Double.parseDouble(str1);
double x2 = Double.parseDouble(str2);
if (x2 == 0) textArea.setText(str + "\n" + x1);
else textArea.setText(str + "\n" + (x1 + x2) + " & " + (x1 - x2));
}
else if (str.contains("%")) { //百分号运算
String str1 = str.substring(0, str.indexOf('%'));
double x1 = Double.parseDouble(str1);
textArea.setText(str + "\n" + x1/100);
}
else if (str.contains("-")) { //减法运算
if(str.charAt(0) == '-') { //如果第一个字符是“-”，形如-2-3形式，就转化成为-(2+3)形式
String str_x = str;
str = str.substring(1);
String str1 = str.substring(0, str.indexOf('-'));
String str2 = str.substring(str.indexOf('-') + 1, str.indexOf('='));
double x1 = Double.parseDouble(str1);
double x2 = Double.parseDouble(str2);
textArea.setText(str_x + "\n" + (-x1-x2));
}
else {
String str1 = str.substring(0, str.indexOf('-'));
String str2 = str.substring(str.indexOf('-') + 1, str.indexOf('='));
double x1 = Double.parseDouble(str1);
double x2 = Double.parseDouble(str2);
textArea.setText(str + "\n" + (x1-x2));
}
}
}
}
6、传文本，查看
class ClearListener implements ActionListener {
JTextArea textArea;
public ClearListener(JTextArea textArea1) { //将按钮和文本区传入
textArea = textArea1;
}
public void actionPerformed(ActionEvent e) { //设置文本区
textArea.setText("");
}
}
class BackListener implements ActionListener {
JTextArea textArea;
String str;
public BackListener(JTextArea textArea1) { //将文本区传入
textArea = textArea1;
}
public void actionPerformed(ActionEvent e) { //设置文本区
str = textArea.getText();
if(str.length() == 0) textArea.setText(""); //如果文本区内容为空，输出为空
else { //否则让当前文本区删掉最后一个符号/数字
str = str.substring(0, str.length()-1);
textArea.setText(str);
}
}
}
class TextListener implements ActionListener {
JButton button;
JTextArea textArea;
public TextListener(JButton button1, JTextArea textArea1) { //将按钮和文本区传入
textArea = textArea1;
button = button1;
}
public void actionPerformed(ActionEvent e) { //设置文本区
textArea.setText(textArea.getText() + button.getText());
}
}
最后——主函数
public class Main {
public static void main(String[] args) {
new WindowOperation();
}
}
完整代码
calculator ($1537) · 代码片段 · 代码片段 · GitCode
