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实现思路
通过点击按钮可以得到一个算术表达式，并且它是一个字符串类型，然后需要做的就是把这个字符串转化为计算机可计算的形式。这里就需要用到中缀表达式转化为后缀表达式。转化完之后通过栈来一步步的进行输出和计算，最后输出结果。
实现过程和代码
1.界面设计
设计效果如图所示：
由图片可知，总共设计了两个文本框和33个按钮（这里的布局是我直接用setBounds()方法设计的。因为如果用布局管理器的话要达到自己想要的效果不太方便）。
在设计时要注意的是：
不能把按钮和文本框直接加入JFrame中，因为如果JFrame.setLayout(null)的话，面板上就会出问题，什么都看不到或者其他情况。因此建议创建一个JPanel，把JPanel的setLayout()设置为空。把按钮和文本框加入到JPanel中，再把JPanel加入到JFrame中。就不会出问题了。JFrame的布局管理器默认为流式布局，位置是中心区域。
设计完长度后，宽度一般要再加15个像素点，高度要再加35个像素点.要不然会有一部分按钮看不到。如我本意要设计的面板宽为600，高为400，则实际上是
jFrame.setSize(614, 437);下面就是我设计的界面的代码：
private JFrame jFrame = new JFrame("计算器");//设置字体，是否加粗，大小 private FontUIResource f = new FontUIResource("隶书", 1, 20); private FontUIResource f1 = new FontUIResource("楷书", 0, 35); private JPanel jPanel = new JPanel(); private int buttonx = 100; private int buttony = 50; private int yy = 50; //两个文本框 private JTextField jTextField1 = new JTextField("0", 30); private JTextField jTextField2 = new JTextField("输入要求在main()中", 30); private String str = ""; private String temp = ""; private int indexYN = 0; private String[] strings = { "(", ")", "1/x", "x^2", "x^3", "x^y", "x!", "√", "e", "ln", "log", "%", "sin", "cos", "tan", "π", "+", "=", "7", "8", "9", "0", "-", "4", "5", "6", ".", "*", "1", "2", "3", "c", "÷" }; //33个按钮 private JButton[] buttons = new JButton[33]; public void loAsi(){ int tep = 0; for (int i = 0; i < 3; i++) { for (int j = 0; j < 6; j++) { buttons[tep] = new JButton(strings[tep]); buttons[tep].setFont(f); buttons[tep++].setFocusable(false); } } for (int i = 0; i < 3; i++) { for (int j = 0; j < 5; j++) { buttons[tep] = new JButton(strings[tep]); buttons[tep].setFont(f); buttons[tep++].setFocusable(false); } } int lo = 0; for (int i = 0; i < 2; i++) { for (int j = 0; j < 6; j++) { buttons[lo++].setBounds(buttonx * j, yy * (2 + i), buttonx, buttony); } } for (int i = 0; i < 5; i++) { buttons[lo++].setBounds(buttonx * i, yy * 4, buttonx, buttony); } buttons[lo++].setBounds(buttonx * 5, yy * 4, buttonx, buttony * 4); for (int i = 0; i < 3; i++) { for (int j = 0; j < 5; j++) { buttons[lo++].setBounds(buttonx * j, yy * (5 + i), buttonx, buttony); } } jTextField1.setBounds(0, yy, 600, yy);//设置位置 jTextField1.setFont(f1);设置字体 jTextField1.setHorizontalAlignment(JLabel.RIGHT);//文本靠右 jTextField1.setEditable(false);//不可修改 jTextField1.setBackground(Color.WHITE);//颜色为白色 jTextField2.setBounds(0, 0, 600, yy); jTextField2.setFont(f1); jTextField2.setHorizontalAlignment(JLabel.RIGHT); jTextField2.setEditable(false); jTextField2.setBackground(Color.WHITE); } public void initButton(){//把按钮添加到jPanel中 this.loAsi(); jPanel.add(jTextField1); jPanel.add(jTextField2); for (int i = 0; i < buttons.length; i++) { jPanel.add(buttons[i]); } jPanel.setLayout(null);//布局管理器为空，自定义设计 } public void init(){ this.initButton(); this.buttonLister(); jFrame.add(jPanel);//把jPanel添加到jFrame中 jFrame.setSize(614, 437);//jFrame的长宽 jFrame.setResizable(false);//大小不可修改 jFrame.setLocationRelativeTo(null);//位置为显示器的正中间 //窗口监听器，点右上角的关闭就关闭窗口 //可以不写，应为JFrame默认的就可以关闭，不需要写事件监听器。如果是Frame的话需要写。 jFrame.addWindowListener(new WindowAdapter() { @Override public void windowClosing(WindowEvent e) { System.exit(0); } }); jFrame.setVisible(true);//设置面板可见 }2.栈，中缀转后缀
我总共设计了12种运算符：（+, -, * , /, ^, !, g, l, o, s, c, t）分别是加，减，乘，除，次方，阶乘，开根号，，对数ln, 对数log2, sin, cos, tan
e是Math.E, p是Math.PI, %是直接乘以0.001
把中缀表达式转换为后缀表达式。例如：
中缀表达式：1+2*3+(l2+3)/2
后缀表达式为：123*+23+2/+
后缀表达式的运算步骤是：
16+23+2/+
2.723+2/+
3.752/+
4.7 2.5+
5.9.5
代码如下：
private List<String> zhongZhui(String str) {//把输入的字符串转换成中缀表达式。存入list中 int index = 0; List<String> list = new ArrayList<>(); do{ char ch = str.charAt(index); if("+-*/^!logsct()".indexOf(str.charAt(index)) >= 0){ //是操作符，直接添加至list中 index ++; list.add(ch+""); }else if (str.charAt(index) == 'e' || str.charAt(index) == 'p'){ index ++; list.add(ch+""); } else if("0123456789".indexOf(str.charAt(index)) >= 0){ //是数字,判断多位数的情况 String str1 = ""; while (index < str.length() && "0123456789.".indexOf(str.charAt(index)) >= 0){ str1 += str.charAt(index); index ++; } list.add(str1); } }while (index < str.length()); return list; } public List<String> houZhui(List<String> list){//中缀表达式转换称后缀表达式 Stack<String> fuZhan = new Stack<>(); List<String> list2 = new ArrayList<>(); if (!list.isEmpty()) { for (int i = 0; i < list.size(); i++) { if (isNumber(list.get(i))){ list2.add(list.get(i)); } else if (list.get(i).charAt(0) == '('){ fuZhan.push(list.get(i)); } else if (isOperator(list.get(i)) && list.get(i).charAt(0) != '('){ if (fuZhan.isEmpty()){ fuZhan.push(list.get(i)); } else {//符栈不为空 if (list.get(i).charAt(0) != ')'){ if (adv(fuZhan.peek()) <= adv(list.get(i))){ //入栈 fuZhan.push(list.get(i)); } else {//出栈 while (!fuZhan.isEmpty() && !"(".equals(fuZhan.peek())){ if(adv(list.get(i)) <= adv(fuZhan.peek())){ list2.add(fuZhan.pop()); } } if (fuZhan.isEmpty() || fuZhan.peek().charAt(0) == '('){ fuZhan.push(list.get(i)); } } } else if (list.get(i).charAt(0) == ')'){ while (fuZhan.peek().charAt(0) != '('){ list2.add(fuZhan.pop()); } fuZhan.pop(); } } } } while (!fuZhan.isEmpty()){ list2.add(fuZhan.pop()); } } else { jTextField1.setText(""); } return list2; } public static boolean isOperator(String op){//判断是否为操作符 if ("0123456789.ep".indexOf(op.charAt(0)) == -1) { return true; } else { return false; } } public static boolean isNumber(String num){//判断是否为操作数 if ("0123456789ep".indexOf(num.charAt(0)) >= 0) { return true; } else { return false; } } public static int adv(String f){//判断操作符的优先级 int result = 0; switch(f) { case "+": result = 1; break; case "-": result = 1; break; case "*": result = 2; break; case "/": result = 2; break; case "^": result = 3; break; case "!": result = 4; break; case "g": result = 4; break; case "l": result = 4; break; case "o": result = 4; break; case "s": result = 4; break; case "c": result = 4; break; case "t": result = 4; break; } return result; }3.判断错误
下面是一些我能想到的一些输入错误和运算错误：
//当只有一位字符时，只能是“0123456789ep”中的一个
//1.第一个字符只能为"losctg(0123456789ep"中的一个
//2.“±/”后面只能是"0123456789losctg(ep"中的一个
//3.".“后面只能是“0123456789”中的一个
//4.”!"后面只能是“±/^)”中的一个
//5."losctg"后面只能是“0123456789(ep”中的一个
//6."0"的判断操作
//1.当0的上一个字符不为"0123456789."时，后一位只能是“±/.!^)”中的一个
//2.如果0的上一位为“.”,则后一位只能是“0123456789±/.^)”中的一个
//3.如果0到上一个运算符之间没有“.”的话，整数位第一个只能是“123456789”，
// 且后一位只能是“0123456789±/.!^)”中的一个。
//4.如果0到上一个运算符之间有一个“.”的话,则后一位只能是“0123456789±/.^)”中的一个
//7."123456789"后面只能是“0123456789±/.!^)”中的一个
//8."(“后面只能是“0123456789locstg()ep”中的一个
//9.”)"后面只能是“±/!^)”中的一个
//10.最后一位字符只能是“0123456789!)ep”中的一个
//12.不能有多个“.”
//13."ep"后面只能是“±*/^)”中的一个
除数不能为0
阶乘必须为自然数
ln的x必须大于0
log的x必须大于0
tan的x不能为±(π/2 + kπ)
括号是否匹配
代码如下：
public void estimate(){//判断输入是否错误 int i = 0; if (str.length() == 0){ } if (str.length() == 1){ //当只有一位字符时，只能是“0123456789ep”中的一个 if ("0123456789ep".indexOf(str.charAt(0)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } } if (str.length() > 1){ for (i = 0; i < str.length() - 1; i++) { //1.第一个字符只能为"losctg(0123456789ep"中的一个 if ("losctg(0123456789ep".indexOf(str.charAt(0)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //2.“+-*/”后面只能是"0123456789losctg(ep"中的一个 if ("+-*/".indexOf(str.charAt(i)) >= 0 && "0123456789losctg(ep".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //3."."后面只能是“0123456789”中的一个 if (str.charAt(i) == '.' && "0123456789".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //4."!"后面只能是“+-*/^)”中的一个 if (str.charAt(i) == '!' && "+-*/^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //5."losctg"后面只能是“0123456789(ep”中的一个 if ("losctg".indexOf(str.charAt(i)) >= 0 && "0123456789(ep".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //6."0"的判断操作 if (str.charAt(0) == '0' && str.charAt(1) == '0'){ jTextField1.setText("输入错误！"); indexYN = 1; } if (i >= 1 && str.charAt(i) == '0'){ //&& str.charAt(0) == '0' && str.charAt(1) == '0' int m = i; int n = i; int is = 0; //1.当0的上一个字符不为"0123456789."时，后一位只能是“+-*/.!^)”中的一个 if ("0123456789.".indexOf(str.charAt(m - 1)) == -1 && "+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //2.如果0的上一位为“.”,则后一位只能是“0123456789+-*/.^)”中的一个 if (str.charAt(m - 1) == '.' && "0123456789+-*/.^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } n -= 1; while (n > 0){ if ("(+-*/^glosct".indexOf(str.charAt(n)) >= 0){ break; } if (str.charAt(n) == '.'){ is++; } n--; } //3.如果0到上一个运算符之间没有“.”的话，整数位第一个只能是“123456789”， // 且后一位只能是“0123456789+-*/.!^)”中的一个。 if ((is == 0 && str.charAt(n) == '0') || "0123456789+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //4.如果0到上一个运算符之间有一个“.”的话,则后一位只能是“0123456789+-*/.^)”中的一个 if (is == 1 && "0123456789+-*/.^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } if (is > 1){ jTextField1.setText("输入错误！"); indexYN = 1; } } //7."123456789"后面只能是“0123456789+-*/.!^)”中的一个 if ("123456789".indexOf(str.charAt(i)) >= 0 && "0123456789+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //8."("后面只能是“0123456789locstg()ep”中的一个 if (str.charAt(i) == '(' && "0123456789locstg()ep".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //9.")"后面只能是“+-*/!^)”中的一个 if (str.charAt(i) == ')' && "+-*/!^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //10.最后一位字符只能是“0123456789!)ep”中的一个 if ("0123456789!)ep".indexOf(str.charAt(str.length() - 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //12.不能有多个“.” if (i > 2 && str.charAt(i) == '.'){ int n = i - 1; int is = 0; while (n > 0){ if ("(+-*/^glosct".indexOf(str.charAt(n)) >= 0){ break; } if (str.charAt(n) == '.'){ is++; } n--; } if (is > 0){ jTextField1.setText("输入错误！"); indexYN = 1; } } //13."ep"后面只能是“+-*/^)”中的一个 if ("ep".indexOf(str.charAt(i)) >= 0 && "+-*/^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } } } }4.计算后缀表达式
代码如下：
public double math(List<String> list2) {//通过后缀表达式进行计算 Stack<String> stack = new Stack<String>(); for (int i = 0; i < list2.size(); i++) { if (isNumber(list2.get(i))) { if (list2.get(i).charAt(0) == 'e'){ stack.push(String.valueOf(Math.E)); } else if (list2.get(i).charAt(0) == 'p'){ stack.push(String.valueOf(Math.PI)); } else { stack.push(list2.get(i)); } } else if (isOperator(list2.get(i))){ double res = 0; if (list2.get(i).equals("+")) { double num2 = Double.parseDouble(stack.pop()); double num1 = Double.parseDouble(stack.pop()); res = num1 + num2; } else if (list2.get(i).equals("-")) { double num2 = Double.parseDouble(stack.pop()); double num1 = Double.parseDouble(stack.pop()); res = num1 - num2; } else if (list2.get(i).equals("*")) { double num2 = Double.parseDouble(stack.pop()); double num1 = Double.parseDouble(stack.pop()); res = num1 * num2; } else if (list2.get(i).equals("/")) { double num2 = Double.parseDouble(stack.pop()); double num1 = Double.parseDouble(stack.pop()); if (num2 != 0){ res = num1 / num2; } else { jTextField1.setText("除数不能为0"); indexYN = 1; } } else if (list2.get(i).equals("^")) { double num2 = Double.parseDouble(stack.pop()); double num1 = Double.parseDouble(stack.pop()); res = Math.pow(num1, num2); } else if (list2.get(i).equals("!")) { double num1 = Double.parseDouble(stack.pop()); if (num1 == 0 || num1 == 1){ res = 1; } else if (num1 == (int)num1 && num1 > 1){ int d = 1; for (int j = (int)num1; j >0; j--) { d *= j; } res = d; } else { jTextField1.setText("阶乘必须为自然数"); indexYN = 1; } } else if (list2.get(i).equals("g")) { double num1 = Double.parseDouble(stack.pop()); res = Math.sqrt(num1); } else if (list2.get(i).equals("l")) { double num1 = Double.parseDouble(stack.pop()); if (num1 > 0){ res = Math.log(num1); } else { jTextField1.setText("ln的x必须大于0"); indexYN = 1; } } else if (list2.get(i).equals("o")) { double num1 = Double.parseDouble(stack.pop()); if (num1 > 0){ res = Math.log(num1) / Math.log(2); } else { jTextField1.setText("log的x必须大于0"); indexYN = 1; } } else if (list2.get(i).equals("s")) { double num1 = Double.parseDouble(stack.pop()); res = Math.sin(num1); } else if (list2.get(i).equals("c")) { double num1 = Double.parseDouble(stack.pop()); res = Math.cos(num1); } else if (list2.get(i).equals("t")) { double num1 = Double.parseDouble(stack.pop()); if (Math.cos(num1) != 0){ res = Math.tan(num1); } else { jTextField1.setText("tan的x不能为+-(π/2 + kπ)"); indexYN = 1; } } stack.push("" + res); } } if (indexYN == 0){ if (!stack.isEmpty()){ return Double.parseDouble(stack.pop()); } else { return 0; } } else { return -999999; } } public void zhanDui(){//进行计算，并且判断括号是否匹配 String khao = ""; int leftkh = 0; int rightkh = 0; int m = 0; //判断括号是否成对 for (int i = 0; i < str.length(); i++) { if (str.charAt(i) == '('){ khao += '('; leftkh++; } if (str.charAt(i) == ')'){ khao += ')'; rightkh++; } } if (leftkh != rightkh){ jTextField1.setText("输入错误！括号不匹配"); indexYN = 1; } if ((leftkh == 0 && rightkh == 0) || ((leftkh == rightkh && leftkh > 0) && khao.charAt(0) == '(' && khao.charAt(khao.length() - 1) == ')')){ if (indexYN == 0){ List<String> list1 = zhongZhui(str); //System.out.println(list1); List<String> list2 = houZhui(list1); //System.out.println(list2); if (indexYN == 0){ if (math(list2) == -999999){ jTextField1.setText(jTextField1.getText()); } else { jTextField1.setText(String.valueOf(math(list2))); jTextField2.setText(String.valueOf(math(list2))); jTextField2.setText(String.valueOf(math(list2))); } } } } else { jTextField1.setText("输入错误！括号不匹配"); indexYN = 1; } }5.事件监听器
因为设置了33个按钮，所以每个按钮都要设计事件监听器，我设置的目的是把点中的按钮的值写入到文本框中输出，并且把它代表的数值或者操作符存放到字符串中，以便于进行中缀转后缀和运算。
代码如下：
public void buttonLister(){//事件监听器 int tep = 0; buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "("); str += "("; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + ")"); str += ")"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "1/"); str += "1/"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "^2"); str += "^2"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "^3"); str += "^3"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "^"); str += "^"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "!"); str += "!"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "√"); str += "g"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "e"); str += "e"; //str += "2.7182818284590452354"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "ln"); str += "l"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "log"); str += "o"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "%"); str += "*0.01"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "sin"); str += "s"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "cos"); str += "c"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "tan"); str += "t"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "π"); str += "p"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "+"); str += "+"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { if (str != ""){ estimate(); zhanDui(); } else { str = ""; } } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "7"); str += "7"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "8"); str += "8"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "9"); str += "9"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "0"); str += "0"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "-"); str += "-"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "4"); str += "4"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "5"); str += "5"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "6"); str += "6"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "."); str += "."; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "*"); str += "*"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "1"); str += "1"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "2"); str += "2"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "3"); str += "3"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(""); str = ""; indexYN = 0; } }); buttons[tep].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "÷"); str += "/"; } }); }完整代码
直接拷贝到Java中就可以用：
一个类走完程序。
main函数中还可以设置面板风格。有
Niumbus风格
Windows风格
Windows经典风格
三种风格可以自定义选择，我个人觉得Niumbus风格比较好看。选择哪一个就释放哪一个，把另外两个注释掉就可以了。
package com.lmdxyt;import javax.swing.*;import javax.swing.plaf.FontUIResource;import java.awt.*;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.WindowAdapter;import java.awt.event.WindowEvent;import java.util.ArrayList;import java.util.List;import java.util.Stack;public class JSQ { private JFrame jFrame = new JFrame("计算器"); private FontUIResource f = new FontUIResource("隶书", 1, 20); private FontUIResource f1 = new FontUIResource("楷书", 0, 35); private JPanel jPanel = new JPanel(); private int buttonx = 100; private int buttony = 50; private int yy = 50; private JTextField jTextField1 = new JTextField("0", 30); private JTextField jTextField2 = new JTextField("输入要求在main()中", 30); private String str = ""; private String temp = ""; private int indexYN = 0; private String[] strings = { "(", ")", "1/x", "x^2", "x^3", "x^y", "x!", "√", "e", "ln", "log", "%", "sin", "cos", "tan", "π", "+", "=", "7", "8", "9", "0", "-", "4", "5", "6", ".", "*", "1", "2", "3", "c", "÷" }; private JButton[] buttons = new JButton[33]; public void loAsi(){ int tep = 0; for (int i = 0; i < 3; i++) { for (int j = 0; j < 6; j++) { buttons[tep] = new JButton(strings[tep]); buttons[tep].setFont(f); buttons[tep++].setFocusable(false); } } for (int i = 0; i < 3; i++) { for (int j = 0; j < 5; j++) { buttons[tep] = new JButton(strings[tep]); buttons[tep].setFont(f); buttons[tep++].setFocusable(false); } } int lo = 0; for (int i = 0; i < 2; i++) { for (int j = 0; j < 6; j++) { buttons[lo++].setBounds(buttonx * j, yy * (2 + i), buttonx, buttony); } } for (int i = 0; i < 5; i++) { buttons[lo++].setBounds(buttonx * i, yy * 4, buttonx, buttony); } buttons[lo++].setBounds(buttonx * 5, yy * 4, buttonx, buttony * 4); for (int i = 0; i < 3; i++) { for (int j = 0; j < 5; j++) { buttons[lo++].setBounds(buttonx * j, yy * (5 + i), buttonx, buttony); } } jTextField1.setBounds(0, yy, 600, yy); jTextField1.setFont(f1); jTextField1.setHorizontalAlignment(JLabel.RIGHT); jTextField1.setEditable(false); jTextField1.setBackground(Color.WHITE); jTextField2.setBounds(0, 0, 600, yy); jTextField2.setFont(f1); jTextField2.setHorizontalAlignment(JLabel.RIGHT); jTextField2.setEditable(false); jTextField2.setBackground(Color.WHITE); } public void initButton(){//把按钮添加到jPanel中 this.loAsi(); jPanel.add(jTextField1); jPanel.add(jTextField2); for (int i = 0; i < buttons.length; i++) { jPanel.add(buttons[i]); } jPanel.setLayout(null); } private List<String> zhongZhui(String str) {//把输入的字符串转换成中缀表达式。存入list中 int index = 0; List<String> list = new ArrayList<>(); do{ char ch = str.charAt(index); if("+-*/^!logsct()".indexOf(str.charAt(index)) >= 0){ //是操作符，直接添加至list中 index ++; list.add(ch+""); }else if (str.charAt(index) == 'e' || str.charAt(index) == 'p'){ index ++; list.add(ch+""); } else if("0123456789".indexOf(str.charAt(index)) >= 0){ //是数字,判断多位数的情况 String str1 = ""; while (index < str.length() && "0123456789.".indexOf(str.charAt(index)) >= 0){ str1 += str.charAt(index); index ++; } list.add(str1); } }while (index < str.length()); return list; } public List<String> houZhui(List<String> list){//中缀表达式转换称后缀表达式 Stack<String> fuZhan = new Stack<>(); List<String> list2 = new ArrayList<>(); if (!list.isEmpty()) { for (int i = 0; i < list.size(); i++) { if (isNumber(list.get(i))){ list2.add(list.get(i)); } else if (list.get(i).charAt(0) == '('){ fuZhan.push(list.get(i)); } else if (isOperator(list.get(i)) && list.get(i).charAt(0) != '('){ if (fuZhan.isEmpty()){ fuZhan.push(list.get(i)); } else {//符栈不为空 if (list.get(i).charAt(0) != ')'){ if (adv(fuZhan.peek()) <= adv(list.get(i))){ //入栈 fuZhan.push(list.get(i)); } else {//出栈 while (!fuZhan.isEmpty() && !"(".equals(fuZhan.peek())){ if(adv(list.get(i)) <= adv(fuZhan.peek())){ list2.add(fuZhan.pop()); } } if (fuZhan.isEmpty() || fuZhan.peek().charAt(0) == '('){ fuZhan.push(list.get(i)); } } } else if (list.get(i).charAt(0) == ')'){ while (fuZhan.peek().charAt(0) != '('){ list2.add(fuZhan.pop()); } fuZhan.pop(); } } } } while (!fuZhan.isEmpty()){ list2.add(fuZhan.pop()); } } else { jTextField1.setText(""); } return list2; } public static boolean isOperator(String op){//判断是否为操作符 if ("0123456789.ep".indexOf(op.charAt(0)) == -1) { return true; } else { return false; } } public static boolean isNumber(String num){//判断是否为操作数 if ("0123456789ep".indexOf(num.charAt(0)) >= 0) { return true; } else { return false; } } public static int adv(String f){//判断操作符的优先级 int result = 0; switch(f) { case "+": result = 1; break; case "-": result = 1; break; case "*": result = 2; break; case "/": result = 2; break; case "^": result = 3; break; case "!": result = 4; break; case "g": result = 4; break; case "l": result = 4; break; case "o": result = 4; break; case "s": result = 4; break; case "c": result = 4; break; case "t": result = 4; break; } return result; } public void buttonLister(){//事件监听器 int tep = 0; buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "("); str += "("; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + ")"); str += ")"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "1/"); str += "1/"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "^2"); str += "^2"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "^3"); str += "^3"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "^"); str += "^"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "!"); str += "!"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "√"); str += "g"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "e"); str += "e"; //str += "2.7182818284590452354"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "ln"); str += "l"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "log"); str += "o"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "%"); str += "*0.01"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "sin"); str += "s"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "cos"); str += "c"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "tan"); str += "t"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "π"); str += "p"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "+"); str += "+"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { if (str != ""){ estimate(); zhanDui(); } else { str = ""; } } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "7"); str += "7"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "8"); str += "8"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "9"); str += "9"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "0"); str += "0"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "-"); str += "-"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "4"); str += "4"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "5"); str += "5"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "6"); str += "6"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "."); str += "."; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "*"); str += "*"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "1"); str += "1"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "2"); str += "2"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "3"); str += "3"; } }); buttons[tep++].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(""); str = ""; indexYN = 0; } }); buttons[tep].addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { jTextField1.setText(jTextField1.getText() + "÷"); str += "/"; } }); } public void init(){ this.initButton(); this.buttonLister(); jFrame.add(jPanel); jFrame.setSize(614, 437); jFrame.setResizable(false); jFrame.setLocationRelativeTo(null); jFrame.addWindowListener(new WindowAdapter() { @Override public void windowClosing(WindowEvent e) { System.exit(0); } }); jFrame.setVisible(true); } public void estimate(){//判断输入是否错误 int i = 0; if (str.length() == 0){ } if (str.length() == 1){ //当只有一位字符时，只能是“0123456789ep”中的一个 if ("0123456789ep".indexOf(str.charAt(0)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } } if (str.length() > 1){ for (i = 0; i < str.length() - 1; i++) { //1.第一个字符只能为"losctg(0123456789ep"中的一个 if ("losctg(0123456789ep".indexOf(str.charAt(0)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //2.“+-*/”后面只能是"0123456789losctg(ep"中的一个 if ("+-*/".indexOf(str.charAt(i)) >= 0 && "0123456789losctg(ep".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //3."."后面只能是“0123456789”中的一个 if (str.charAt(i) == '.' && "0123456789".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //4."!"后面只能是“+-*/^)”中的一个 if (str.charAt(i) == '!' && "+-*/^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //5."losctg"后面只能是“0123456789(ep”中的一个 if ("losctg".indexOf(str.charAt(i)) >= 0 && "0123456789(ep".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //6."0"的判断操作 if (str.charAt(0) == '0' && str.charAt(1) == '0'){ jTextField1.setText("输入错误！"); indexYN = 1; } if (i >= 1 && str.charAt(i) == '0'){ //&& str.charAt(0) == '0' && str.charAt(1) == '0' int m = i; int n = i; int is = 0; //1.当0的上一个字符不为"0123456789."时，后一位只能是“+-*/.!^)”中的一个 if ("0123456789.".indexOf(str.charAt(m - 1)) == -1 && "+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //2.如果0的上一位为“.”,则后一位只能是“0123456789+-*/.^)”中的一个 if (str.charAt(m - 1) == '.' && "0123456789+-*/.^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } n -= 1; while (n > 0){ if ("(+-*/^glosct".indexOf(str.charAt(n)) >= 0){ break; } if (str.charAt(n) == '.'){ is++; } n--; } //3.如果0到上一个运算符之间没有“.”的话，整数位第一个只能是“123456789”， // 且后一位只能是“0123456789+-*/.!^)”中的一个。 if ((is == 0 && str.charAt(n) == '0') || "0123456789+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //4.如果0到上一个运算符之间有一个“.”的话,则后一位只能是“0123456789+-*/.^)”中的一个 if (is == 1 && "0123456789+-*/.^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } if (is > 1){ jTextField1.setText("输入错误！"); indexYN = 1; } } //7."123456789"后面只能是“0123456789+-*/.!^)”中的一个 if ("123456789".indexOf(str.charAt(i)) >= 0 && "0123456789+-*/.!^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //8."("后面只能是“0123456789locstg()ep”中的一个 if (str.charAt(i) == '(' && "0123456789locstg()ep".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //9.")"后面只能是“+-*/!^)”中的一个 if (str.charAt(i) == ')' && "+-*/!^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //10.最后一位字符只能是“0123456789!)ep”中的一个 if ("0123456789!)ep".indexOf(str.charAt(str.length() - 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } //12.不能有多个“.” if (i > 2 && str.charAt(i) == '.'){ int n = i - 1; int is = 0; while (n > 0){ if ("(+-*/^glosct".indexOf(str.charAt(n)) >= 0){ break; } if (str.charAt(n) == '.'){ is++; } n--; } if (is > 0){ jTextField1.setText("输入错误！"); indexYN = 1; } } //13."ep"后面只能是“+-*/^)”中的一个 if ("ep".indexOf(str.charAt(i)) >= 0 && "+-*/^)".indexOf(str.charAt(i + 1)) == -1){ jTextField1.setText("输入错误！"); indexYN = 1; } } } } public double math(List<String> list2) {//通过后缀表达式进行计算 Stack<String> stack = new Stack<String>(); for (int i = 0; i < list2.size(); i++) { if (isNumber(list2.get(i))) { if (list2.get(i).charAt(0) == 'e'){ stack.push(String.valueOf(Math.E)); } else if (list2.get(i).charAt(0) == 'p'){ stack.push(String.valueOf(Math.PI)); } else { stack.push(list2.get(i)); } } else if (isOperator(list2.get(i))){ double res = 0; if (list2.get(i).equals("+")) { double num2 = Double.parseDouble(stack.pop()); double num1 = Double.parseDouble(stack.pop()); res = num1 + num2; } else if (list2.get(i).equals("-")) { double num2 = Double.parseDouble(stack.pop()); double num1 = Double.parseDouble(stack.pop()); res = num1 - num2; } else if (list2.get(i).equals("*")) { double num2 = Double.parseDouble(stack.pop()); double num1 = Double.parseDouble(stack.pop()); res = num1 * num2; } else if (list2.get(i).equals("/")) { double num2 = Double.parseDouble(stack.pop()); double num1 = Double.parseDouble(stack.pop()); if (num2 != 0){ res = num1 / num2; } else { jTextField1.setText("除数不能为0"); indexYN = 1; } } else if (list2.get(i).equals("^")) { double num2 = Double.parseDouble(stack.pop()); double num1 = Double.parseDouble(stack.pop()); res = Math.pow(num1, num2); } else if (list2.get(i).equals("!")) { double num1 = Double.parseDouble(stack.pop()); if (num1 == 0 || num1 == 1){ res = 1; } else if (num1 == (int)num1 && num1 > 1){ int d = 1; for (int j = (int)num1; j >0; j--) { d *= j; } res = d; } else { jTextField1.setText("阶乘必须为自然数"); indexYN = 1; } } else if (list2.get(i).equals("g")) { double num1 = Double.parseDouble(stack.pop()); res = Math.sqrt(num1); } else if (list2.get(i).equals("l")) { double num1 = Double.parseDouble(stack.pop()); if (num1 > 0){ res = Math.log(num1); } else { jTextField1.setText("ln的x必须大于0"); indexYN = 1; } } else if (list2.get(i).equals("o")) { double num1 = Double.parseDouble(stack.pop()); if (num1 > 0){ res = Math.log(num1) / Math.log(2); } else { jTextField1.setText("log的x必须大于0"); indexYN = 1; } } else if (list2.get(i).equals("s")) { double num1 = Double.parseDouble(stack.pop()); res = Math.sin(num1); } else if (list2.get(i).equals("c")) { double num1 = Double.parseDouble(stack.pop()); res = Math.cos(num1); } else if (list2.get(i).equals("t")) { double num1 = Double.parseDouble(stack.pop()); if (Math.cos(num1) != 0){ res = Math.tan(num1); } else { jTextField1.setText("tan的x不能为+-(π/2 + kπ)"); indexYN = 1; } } stack.push("" + res); } } if (indexYN == 0){ if (!stack.isEmpty()){ return Double.parseDouble(stack.pop()); } else { return 0; } } else { return -999999; } } public void zhanDui(){//进行计算，并且判断括号是否匹配 String khao = ""; int leftkh = 0; int rightkh = 0; int m = 0; //判断括号是否成对 for (int i = 0; i < str.length(); i++) { if (str.charAt(i) == '('){ khao += '('; leftkh++; } if (str.charAt(i) == ')'){ khao += ')'; rightkh++; } } if (leftkh != rightkh){ jTextField1.setText("输入错误！括号不匹配"); indexYN = 1; } if ((leftkh == 0 && rightkh == 0) || ((leftkh == rightkh && leftkh > 0) && khao.charAt(0) == '(' && khao.charAt(khao.length() - 1) == ')')){ if (indexYN == 0){ List<String> list1 = zhongZhui(str); //System.out.println(list1); List<String> list2 = houZhui(list1); //System.out.println(list2); if (indexYN == 0){ if (math(list2) == -999999){ jTextField1.setText(jTextField1.getText()); } else { jTextField1.setText(String.valueOf(math(list2))); jTextField2.setText(String.valueOf(math(list2))); jTextField2.setText(String.valueOf(math(list2))); } } } } else { jTextField1.setText("输入错误！括号不匹配"); indexYN = 1; } } public static void main(String[] args) { new JSQ().init(); //Niumbus风格 try { UIManager.setLookAndFeel("javax.swing.plaf.nimbus.NimbusLookAndFeel"); } catch (ClassNotFoundException ex) { ex.printStackTrace(); } catch (InstantiationException ex) { ex.printStackTrace(); } catch (IllegalAccessException ex) { ex.printStackTrace(); } catch (UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } }}关于“java如何实现科学计算器”这篇文章的内容就介绍到这里，感谢各位的阅读！相信大家对“java如何实现科学计算器”知识都有一定的了解，大家如果还想学习更多知识，欢迎关注编程网行业资讯频道。
