整体布局采用BorderLayout，Center为程序主要交互部分，North为菜单界面。
主要界面由两个采用GridLayout分布的子面板组成，两个面板分别显示计算过程和交互按钮。
-主要使用控件-JLabel：通过标签显示计算式与结果。
JButton：通过按钮实现程序与用户的基本交互。
JPanel：通过面板组建程序图形界面的基本布局。
JMenubar/JMenu/JMenuItem：用于组建菜单。
Font：用于设置字体样式。
-数据结构-通过数字栈与符号栈完成对算式的计算算法。
通过哈希表建立符号名称到按钮的映射。
public class calculator {
public static void main(String[] argv) {
new app();
}
}import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class app extends JFrame {
private static String ex = "";
private static JLabel expression, res;// 分别存储表达式 计算结果
private static Stacksign_stack = new Stack();// 符号栈
private static Stacknumber_stack = new Stack();// 数字栈
private static Double curIndex, totIndex;// 当前数字结果 整个表达式的数字结果
private static final String buttonName[][] = { { "C", "÷", "×", "Back" }, { "7", "8", "9", "-" },
{ "4", "5", "6", "+" },
{ "1", "2", "3", "√" }, { "%", "0", ".", "=" } };
private static JButton buttonList[][] = new JButton[5][4];
private static HashMapbuttonMap = new HashMap();// 映射 符号->按钮
private static JMenuItem standardMode, sciMode, appearance, history;
private static Double unit = 1.0;// 用来记录小数最小单位
// 计算结果并更新
private static void calculate() {
totIndex = 0.0;
Stacksstack = (Stack) sign_stack.clone();
Stacknstack = (Stack) number_stack.clone();
if (sstack.empty() || sstack.firstElement() != '÷')
nstack.push(curIndex);
else {
sstack.pop();
sstack.push('×');
nstack.push(1 / curIndex);
}
unit = 1.0;
while (!sstack.empty()) {
Character s = sstack.pop();
if (s == '+') {
double a = nstack.pop();
totIndex += a;
} else if (s == '-') {
double a = nstack.pop();
totIndex -= a;
} else if (s == '×') {
double a = nstack.pop(), b = nstack.pop();
nstack.push(a * b);
} else if (s == '÷') {
double a = nstack.pop(), b = nstack.pop();
nstack.push(b / a);
}
}
totIndex += nstack.pop();
}
// 数字按键事件
private static void NumberButtonAction(int n) {
if (number_stack.size()< sign_stack.size()) {
number_stack.push(curIndex);
curIndex = 0.0;
}
if (unit.equals(1.0)) {
curIndex = curIndex * 10 + n;
} else {
curIndex += n * unit;
unit /= 10;
}
res.setText(tool.Rounding(Double.toString(curIndex)));
ex += (char) (n + 48);
expression.setText(ex);
}
// 符号按键事件
private static void SignButtonAction(char sign) {
calculate();
res.setText(tool.Rounding(Double.toString(totIndex)));
if (sign_stack.empty() || sign_stack.firstElement() != '÷')
number_stack.push(curIndex);
else {
sign_stack.pop();
sign_stack.push('×');
number_stack.push(1 / curIndex);
}
unit = 1.0;
curIndex = 0.0;
sign_stack.push(sign);
ex += sign;
expression.setText(ex);
}
private static void buttonAction() {
buttonMap.get("1").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
NumberButtonAction(1);
}
});
buttonMap.get("2").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
NumberButtonAction(2);
}
});
buttonMap.get("3").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
NumberButtonAction(3);
}
});
buttonMap.get("4").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
NumberButtonAction(4);
}
});
buttonMap.get("5").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
NumberButtonAction(5);
}
});
buttonMap.get("6").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
NumberButtonAction(6);
}
});
buttonMap.get("7").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
NumberButtonAction(7);
}
});
buttonMap.get("8").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
NumberButtonAction(8);
}
});
buttonMap.get("9").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
NumberButtonAction(9);
}
});
buttonMap.get("0").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
NumberButtonAction(0);
}
});
buttonMap.get("C").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
ex = "";
expression.setText(ex);
curIndex = 0.0;
unit = 1.0;
res.setText(tool.Rounding(Double.toString(curIndex)));
sign_stack.clear();
}
});
buttonMap.get("=").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
calculate();
number_stack.clear();
sign_stack.clear();
res.setText(tool.Rounding(Double.toString(totIndex)));
number_stack.push(totIndex);
curIndex = totIndex;
ex = tool.Rounding(Double.toString(curIndex));
expression.setText(ex);
}
});
buttonMap.get("+").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
SignButtonAction('+');
}
});
buttonMap.get("-").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
SignButtonAction('-');
}
});
buttonMap.get("×").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
SignButtonAction('×');
}
});
buttonMap.get("÷").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
SignButtonAction('÷');
}
});
buttonMap.get("Back").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (ex.length() == 0) {
return;
}
char c = ex.charAt(ex.length() - 1);
ex = ex.substring(0, ex.length() - 1);
if (c == '.') {
unit = 1.0;
} else if (!unit.equals(1.0)) {
unit *= 10;
curIndex -= (c - 48) * unit;
} else {
if (c >= '0' && c<= '9') {
curIndex -= c - 48;
curIndex /= 10;
} else {
sign_stack.pop();
curIndex = number_stack.pop();
unit = tool.getDecimalUnit(curIndex);
}
}
expression.setText(ex);
res.setText(tool.Rounding(Double.toString(curIndex)));
}
});
buttonMap.get(".").addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
if (ex.charAt(ex.length() - 1) == '.')// 防止小数点重复输入
return;
ex += '.';
expression.setText(ex);
unit /= 10;
}
});
}
private void UI() {
this.setLayout(new BorderLayout());
// 设置字体格式
Font font = new Font("黑体", Font.PLAIN, 50);
Font buttonFont = new Font("黑体", Font.PLAIN, 25);
Font menuFont = new Font("黑体", Font.PLAIN, 12);
// 菜单
JMenuBar bar = new JMenuBar();
JMenu mode = new JMenu("模式");
mode.setFont(menuFont);
standardMode = new JMenuItem("标准");
sciMode = new JMenuItem("科学");
mode.add(standardMode);
mode.add(sciMode);
JMenu func = new JMenu("功能");
func.setFont(menuFont);
appearance = new JMenuItem("外观设置");
history = new JMenuItem("历史记录");
func.add(appearance);
func.add(history);
bar.add(mode);
bar.add(func);
this.add("North", bar);
//总面板
JPanel panel = new JPanel(new GridLayout(2, 1));
// 分面板一：计算器显示界面
JPanel show = new JPanel(new GridLayout(2, 1));
expression = new JLabel();// 算术表达式
expression.setFont(font);
res = new JLabel(tool.Rounding(Double.toString(curIndex)));// 计算结果
res.setFont(new Font("黑体", Font.PLAIN, 35));
show.add(expression);
show.add(res);
// 分面板二：计算机按键
JPanel buttonPanel = new JPanel(new GridLayout(5, 4));
for (int i = 0; i< 5; i++) {
for (int j = 0; j< 4; j++) {
buttonList[i][j] = new JButton(buttonName[i][j]);
buttonMap.put(buttonName[i][j], buttonList[i][j]);
if (buttonName[i][j].equals("Back"))
buttonList[i][j].setFont(new Font("黑体", Font.PLAIN, 20));
else
buttonList[i][j].setFont(buttonFont);
if (buttonName[i][j].equals("="))
buttonList[i][j].setBackground(new Color(65, 105, 225));
else if (i >= 1 && j<= 2)
buttonList[i][j].setBackground(Color.white);
buttonPanel.add(buttonList[i][j]);
}
}
panel.add(show);
panel.add(buttonPanel);
this.add(panel);
//JFrame基本设置
this.setVisible(true);
this.setBounds(400, 150, 390, 550);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setTitle("烨的计算器");
}
app() {
curIndex = 0.0;
totIndex = 0.0;
UI();
buttonAction();
}
} public abstract class tool {
// 省略小数末尾的0
public static String Rounding(String s) {
if (s.lastIndexOf('.', s.length() - 1) == -1) {
return s;
}
int i = s.length() - 1;
for (; i >= 0; i--) {
if (s.charAt(i) == '.')
break;
if (s.charAt(i) != '0') {
return s.substring(0, i + 1);
}
}
return s.substring(0, i);
}
// 获取最小小数单位
public static Double getDecimalUnit(Double n) {
String s = Double.toString(n);
if (s.indexOf('.') == -1) {
return 1.0;
}
return Math.pow(0.1, s.length() - s.indexOf('.'));
}
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