二代计算器完成除了同层括号问题之外其他问题都已解决
    可以简单的实现四则运算及括号优先运算（实现失败）

    1. package gouzao;
    2. import java.awt.*;
    3. import java.awt.event.*;
    4. import java.text.DecimalFormat;
    5. import java.text.DecimalFormat;
    6. import javax.swing.*;
    8. import org.omg.CORBA.TCKind;
    9. public class computer extends JFrame implements ActionListener{
    10.     String[] str= {"7","8","9","DEL","Replay","4","5","6","×","÷","1","2","3","+","-","0","(",")","=","end"};
    11.     JPanel p = new JPanel();
    12.     DecimalFormat df = new DecimalFormat("0");
    13.     int round=0,round1=0;
    14.     char un=' ';
    15.     int x=1,o=0,s=0,y=0,r=0,m=0,w=0,l=0,d=0,kl=0;//开关：x表示字符长度，o判断用户在输入运算符之前是否按了0键（o为0时其他数字键可以替代0）
    16.     //s，y，m,w判断用户是否输入了+，-，×,÷键（控制用户防止用户输入两次同样的运算符及其他非法操作），r判断用户是否输入加减乘除；
    17.     double sum=0,befor=0,k=0;
    18.     char c[]= {'/','/','/','/','/','/','/','/','/','/','/','/','/','/','/'};
    19.     JTextField textA;
    20.     String t="0                     ";
    21.     public computer() {
    22.         setLayout(new BorderLayout());
    23.         setFont(new Font("Arial",Font.PLAIN,14));
    24.         textA = new JTextField("",5);
    25.         textA.setFont(new Font("Arial",Font.PLAIN,30));
    26.         textA.disable();
    27.         getContentPane().add("North",textA);
    28.         p.setLayout(new GridLayout(4,5));
    29.         for(int i=0;i<20;i++) {
    30.             JButton b = new JButton(str[i]);
    31.             b.addActionListener(this);
    32.             b.setActionCommand(str[i]);
    33.             p.add(b);
    34.         }
    35.         getContentPane().add("Center",p);
    36.     }
    37.     public static void main(String[] agrs) {
    38.         computer c = new computer();
    39.         c.setTitle("计算器");
    40.         c.pack();
    41.         c.setVisible(true);
    42.         c.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    43.         c.setLocationRelativeTo(null);
    44.         while(true) {
    45.             c.textA.setText(c.t);
    46.         }
    47.     }
    48.     public void actionPerformed(ActionEvent e) {
    49.         if(e.getActionCommand().equals("7")) {
    50.             if(x==15||d==1) {
    51.                 return;
    52.             }else if(t.charAt(0)=='0'&&s==0&&y==0&&m==0&&r==0) {
    53.                 x=x-1;}
    54.             if(o==1) {
    55.                 x=x-1;
    56.                 o=0;
    57.             }
    58.             StringBuilder strBuilder = new StringBuilder(t);
    59.             strBuilder.setCharAt(x,'7');
    60.             strBuilder.toString();
    61.             t=strBuilder.toString();
    62.             x=x+1;
    63.             s=0;y=0;m=0;w=0;l=0;;
    64.             }else if(e.getActionCommand().equals("8")) {
    65.             if(x==15||d==1) {
    66.                 return;
    67.             }else if(t.charAt(0)=='0'&&s==0&&y==0&&m==0&&r==0){//为0时退格
    68.                 x=x-1;}
    69.             if(o==1) {
    70.                 x=x-1;
    71.                 o=0;
    72.             }
    73.             StringBuilder strBuilder = new StringBuilder(t);
    74.             strBuilder.setCharAt(x,'8');
    75.             strBuilder.toString();
    76.             t=strBuilder.toString();
    77.             x=x+1;
    78.             s=0;y=0;m=0;w=0;l=0;;
    79.         }else if(e.getActionCommand().equals("9")) {
    80.             if(x==15||d==1) {
    81.                 return;
    82.             }else if(t.charAt(0)=='0'&&s==0&&y==0&&m==0&&r==0){//为0时退格
    83.                 x=x-1;}
    84.             if(o==1) {
    85.                 x=x-1;
    86.                 o=0;
    87.             }
    88.             StringBuilder strBuilder = new StringBuilder(t);
    89.             strBuilder.setCharAt(x,'9');
    90.             strBuilder.toString();
    91.             t=strBuilder.toString();
    92.             x=x+1;
    93.             s=0;y=0;m=0;w=0;l=0;;
    94.         }else if(e.getActionCommand().equals("4")) {
    95.             if(x==15||d==1) {
    96.                 return;
    97.             }else if(t.charAt(0)=='0'&&s==0&&y==0&&m==0&&r==0){//为0时退格
    98.                 x=x-1;}
    99.             if(o==1) {
    100.                 x=x-1;
    101.                 o=0;
    102.             }
    103.             StringBuilder strBuilder = new StringBuilder(t);
    104.             strBuilder.setCharAt(x,'4');
    105.             strBuilder.toString();
    106.             t=strBuilder.toString();
    107.             x=x+1;
    108.             s=0;y=0;m=0;w=0;l=0;;
    109.         }else if(e.getActionCommand().equals("5")) {
    110.             if(x==15||d==1) {
    111.                 return;
    112.             }else if(t.charAt(0)=='0'&&s==0&&y==0&&m==0&&r==0){//为0时退格
    113.                 x=x-1;}
    114.             if(o==1) {
    115.                 x=x-1;
    116.                 o=0;
    117.             }
    118.             StringBuilder strBuilder = new StringBuilder(t);
    119.             strBuilder.setCharAt(x,'5');
    120.             strBuilder.toString();
    121.             t=strBuilder.toString();
    122.             x=x+1;
    123.             s=0;y=0;m=0;w=0;l=0;;
    124.         }else if(e.getActionCommand().equals("6")) {
    125.             if(x==15||d==1) {
    126.                 return;
    127.             }else if(t.charAt(0)=='0'&&s==0&&y==0&&m==0&&r==0){//为0时退格
    128.                 x=x-1;}
    129.             if(o==1) {
    130.                 x=x-1;
    131.                 o=0;
    132.             }
    133.             StringBuilder strBuilder = new StringBuilder(t);
    134.             strBuilder.setCharAt(x,'6');
    135.             strBuilder.toString();
    136.             t=strBuilder.toString();
    137.             x=x+1;
    138.             s=0;y=0;m=0;w=0;l=0;;
    139.         }else if(e.getActionCommand().equals("1")) {
    140.             if(x==15||d==1) {
    141.                 return;
    142.             }else if(t.charAt(0)=='0'&&s==0&&y==0&&m==0&&r==0){//为0时退格
    143.                 x=x-1;}
    144.             if(o==1) {
    145.                 x=x-1;
    146.                 o=0;
    147.             }
    148.             StringBuilder strBuilder = new StringBuilder(t);
    149.             strBuilder.setCharAt(x,'1');
    150.             strBuilder.toString();
    151.             t=strBuilder.toString();
    152.             x=x+1;
    153.             s=0;y=0;m=0;w=0;l=0;;
    154.         }else if(e.getActionCommand().equals("2")) {
    155.             if(x==15||d==1) {
    156.                 return;
    157.             }else if(t.charAt(0)=='0'&&s==0&&y==0&&m==0&&r==0){//为0时退格//为0时退格
    158.             x=x-1;
    159.             }
    160.             if(o==1) {
    161.                 x=x-1;
    162.                 o=0;
    163.             }
    164.             StringBuilder strBuilder = new StringBuilder(t);
    165.             strBuilder.setCharAt(x,'2');
    166.             strBuilder.toString();
    167.             t=strBuilder.toString();
    168.             x=x+1;
    169.             s=0;y=0;m=0;w=0;l=0;
    170.         }else if(e.getActionCommand().equals("3")) {
    171.             if(x==15||d==1) {
    172.                 return;
    173.             }else if(t.charAt(0)=='0'&&s==0&&y==0&&m==0&&r==0){//为0时退格
    174.                 x=x-1;}
    175.             if(o==1) {
    176.                 x=x-1;
    177.                 o=0;
    178.             }
    179.             StringBuilder strBuilder = new StringBuilder(t);
    180.             strBuilder.setCharAt(x,'3');
    181.             strBuilder.toString();
    182.             t=strBuilder.toString();
    183.             x=x+1;
    184.             s=0;y=0;m=0;w=0;l=0;
    185.         }else if(e.getActionCommand().equals("0")) {
    186.             if(x==15||d==1) {
    187.                 return;
    188.             }else if(t.charAt(0)=='0'&&r==0){
    189.                 return;
    190.                 }else if(o==1){
    191.                     return;
    192.                 }else 
    194.                     {
    195.             StringBuilder strBuilder = new StringBuilder(t);
    196.             strBuilder.setCharAt(x,'0');
    197.             strBuilder.toString();
    198.             t=strBuilder.toString();
    199.             if(s==1||y==1||m==1) {
    200.             o=1;
    201.             }
    202.             x=x+1;
    203.             s=0;y=0;m=0;w=0;l=0;
    204.                 }
    205.             }else if(e.getActionCommand().equals("+")) {
    206.             if((x==15||x==14)&&(y==0&&m==0&&w==0)) {
    207.                 return;
    208.             }else if(s==1||l==1) {
    209.                 return;
    210.             }else {
    211.                 if(y==1||m==1||w==1){
    212.                     x=x-1;
    213.                 }
    214.                 StringBuilder strBuilder = new StringBuilder(t);
    215.                 strBuilder.setCharAt(x,'+');
    216.                 strBuilder.toString();
    217.                 t=strBuilder.toString();
    218.                 s=1;
    219.                 y=0;
    220.                 w=0;
    221.                 x=x+1;
    222.                 d=0;
    223.                 o=0;
    224.                 r=1;
    225.             }
    226.         }else if(e.getActionCommand().equals("-")) {
    227.             if((x==15||x==14)&&(s==0&&m==0&&w==0)) {
    228.                 return;
    229.             }else if(y==1||l==1) {
    230.                 return;
    231.             }else 
    232.             {
    233.                 if(s==1||m==1||w==1){
    234.                     x=x-1;
    235.                 }
    236.                 StringBuilder strBuilder = new StringBuilder(t);
    237.                 strBuilder.setCharAt(x,'-');
    238.                 strBuilder.toString();
    239.                 t=strBuilder.toString();
    240.                 y=1;
    241.                 s=0;
    242.                 m=0;
    243.                 d=0;
    244.                 w=0;
    245.                 x=x+1;
    246.                 o=0;
    247.                 r=1;
    248.             }
    249.         }else if(e.getActionCommand().equals("=")) {
    250.             int od=0;
    251.             int gl=0;
    252.             int kl=0;
    253.                 for(;round>0;round--) {
    254.                     if(t.charAt(x-1)=='+'||t.charAt(x-1)=='-'||t.charAt(x-1)=='×'||t.charAt(x-1)=='÷')
    255.                         x=x-1;
    256.                     if(t.charAt(x-1)=='(') {
    257.                         StringBuilder strBuilder = new StringBuilder(t);
    258.                         strBuilder.setCharAt(x,' ');
    259.                         strBuilder.toString();
    260.                         t=strBuilder.toString();
    261.                     }
    262.                 StringBuilder strBuilder = new StringBuilder(t);
    263.                 strBuilder.setCharAt(x,')');
    264.                 strBuilder.toString();
    265.                 t=strBuilder.toString();
    266.                 x=x+1;
    267.             }
    268.                 do {
    269.                     if(t.charAt(gl)=='(') {
    270.                         od++;
    271.                     }
    272.                     gl++;
    273.                 }while(t.charAt(gl)!=')'&&t.charAt(gl)!=' ');
    275.             int j=0;
    276.             double []a=new double[15];
    277.             int b=0;
    278.             String[] t2=new String[21];
    279.             while(t.charAt(j)!=' ') {
    280.                 String t1="0                    ";
    281.             for(int i=j;i<20;i++) {
    282.             if(t.charAt(i)>='0'&&t.charAt(i)<='9') {
    283.                 StringBuilder strBuilder1 = new StringBuilder(t1);
    284.                 strBuilder1.setCharAt(i-j,t.charAt(i));
    285.                 strBuilder1.toString();
    286.                 t1=strBuilder1.toString();
    287.             }else {
    288.                 c[b]=t.charAt(i);
    289.                 j=i+1;
    290.                 break;
    291.                 }
    292.             }
    293.             double all=0;
    294.             for(int g=0;g<t1.replace(" ","").length();g++) {
    295.                double u=(int)Math.pow(10,t1.replace(" ","").length()-g-1);
    296.                 all=all+u*Integer.parseInt(t1.charAt(g)+"");
    297.             }
    298.             t2[b]=t1;
    299.             a[b]=all;
    300.             b=b+1;
    301.             }
    302.             if(sum==0||a[0]==befor) {
    303.                 sum=a[0];
    304.             }else {
    305.                 sum=0;
    306.             }
    307.             for(int l=0;l<=100;l++) {
    308.                 System.out.println(round1+" "+c[l]+" "+c[l+1]+" "+l+" "+sum+" "+kl);
    309.                 if(l==0)
    310.                     sum=a[0];
    311.                 if(l!=0) {
    312.                 if(c[l-1]=='(')
    313.                     sum=a[l];
    314.                 }
    315.                 if(c[l]=='+'&&c[l+1]=='(') {
    316.                     sum=sum+k;
    317.                 }else if(c[l]=='-'&&c[l+1]=='(') {
    318.                     sum=sum-k;
    319.                 }else if(c[l]=='÷'&&c[l+1]=='(') {
    320.                     sum=sum/k;
    321.                 }else 
    322.                 if((c[l]=='('&&od==0)||c[l]=='/') {
    323.                     break;
    324.                 }else if(od!=0&&kl==0) {//括号跳转
    325.                 if(round1!=od) {
    326.                     round1=round1+1;
    327.                     while(c[l]!='('){
    328.                         l++;
    329.                     }
    330.                     if(round1==od)
    331.                         kl=1;
    332.                     continue;
    333.                 }
    334.                 }else if(kl==1&&(c[l]=='('||c[l]==')')) {//括号跳转
    335.                 if(od==1) {
    336.                     l=-1;
    337.                     k=sum;
    338.                     od--;
    339.                     round1--;
    340.                     kl=1;
    341.                     }else {
    342.                     round1--;
    343.                     od--;
    344.                     kl=1;
    345.                     l--;
    346.                     while(c[l]!='('&&l!=0){
    347.                         l--;
    348.                     }
    349.                     l--;
    350.                 while(c[l]!='('&&l!=0){
    351.                     l--;
    352.                 }
    353.                 k=sum;
    354.                 continue;
    355.                     }
    357.             }else if(c[l]=='+'&&kl==1) {         //加法
    358.                 if(l!=0) {
    359.                 if(c[l-1]=='(')
    360.                     sum=a[l];
    361.                 }
    362.                 double u=a[l+1];
    363.                 while(c[l+1]=='÷'||c[l+1]=='×') {
    364.                     if(c[l+1]=='×'&&c[l+2]!='(') {
    365.                         u=u*a[l+2];
    366.                     }else if(c[l+1]=='÷'&&c[l+2]!='('){
    367.                         u=u/a[l+2];
    368.                     }else if(c[l+1]=='×'&&c[l+2]=='(') {
    369.                         u=u*k;
    370.                     }else if(c[l+1]=='÷'&&c[l+2]=='(') {
    371.                         u=u/k;
    372.                     }
    373.                     l=l+1;
    374.                 }
    375.                 sum=sum+u;
    376.         }else if(c[l]=='-'&&kl==1) {       //减法
    377.             if(c[l-1]=='(')
    378.                 sum=a[l];
    379.             double u=a[l+1];
    380.             while(c[l+1]=='÷'||c[l+1]=='×') {
    381.                 if(c[l+1]=='×'&&c[l+2]!='(') {
    382.                     u=u*a[l+2];
    383.                 }else if(c[l+1]=='÷'&&c[l+2]!='('){
    384.                     u=u/a[l+2];
    385.                 }else if(c[l+1]=='×'&&c[l+2]=='(') {
    386.                     u=u*k;
    387.                 }else if(c[l+1]=='÷'&&c[l+2]=='(') {
    388.                     u=u/k;
    389.                 }
    390.                 l=l+1;
    391.             }
    392.             sum=sum-u;
    393.         }
    394.                 else if(c[l]=='×'&&kl==1) {    //乘法
    395.                     System.out.println(" "+sum);
    396.                         if(c[l-1]=='(')
    397.                             sum=a[l];
    398.                         double u=a[l+1];
    399.                         if(c[l+1]=='(')
    400.                             u=k;
    401.                         while(c[l+1]=='÷'||c[l+1]=='×') {
    402.                             if(c[l+1]=='×'&&c[l+2]!='(') {
    403.                                 u=u*a[l+2];
    404.                             }else if(c[l+1]=='÷'&&c[l+2]!='('){
    405.                                 u=u/a[l+2];
    406.                             }else if(c[l+1]=='×'&&c[l+2]=='(') {
    407.                                 u=u*k;
    408.                             }else if(c[l+1]=='÷'&&c[l+2]=='(') {
    409.                                 u=u/k;
    410.                             }
    411.                             l=l+1;
    412.                         }
    413.                         sum=sum*u;
    414.                 }else  if(c[l]=='÷'&&kl==1) { ///除法
    415.                     if(c[l-1]=='(')
    416.                         sum=a[l];
    417.                     double u=a[l+1];
    418.                     while(c[l+1]=='÷'||c[l+1]=='×') {
    419.                         if(c[l+1]=='×'&&c[l+2]!='(') {
    420.                             u=u*a[l+2];
    421.                         }else if(c[l+1]=='÷'&&c[l+2]!='('){
    422.                             u=u/a[l+2];
    423.                         }else if(c[l+1]=='×'&&c[l+2]=='(') {
    424.                             u=u*k;
    425.                         }else if(c[l+1]=='÷'&&c[l+2]=='(') {
    426.                             u=u/k;
    427.                         }
    428.                         l=l+1;
    429.                     }
    430.                     sum=sum/u;
    431.                 }
    432.             }
    433.             int f=0;
    434.             for(int m=0;m<b;m++) {
    435.             if(t2[m].replace(" ","").length()>10) {
    436.                 t="error";
    437.                 sum=0;
    438.                 f=1;
    439.             }else if(sum==befor&&befor!=0) {
    440.                 f=1;
    441.             }
    442.             }
    443.             if(f==0) {
    444.             t=String.valueOf(df.format(sum));
    445.             }else {
    446.                 t=String.valueOf(df.format(befor));
    447.             }
    448.             x=t.replace(" ", "").length();
    449.             for(int h=0;h<16-(x-1);h++) {
    450.             t=t+" ";
    451.             }
    452.             t=t.replace("+","");
    453.             t=t.replace("-","");
    454.             t=t.replace("×","");
    455.             befor=sum;
    456.             double wr=0;
    457.             for(int g=0;g<t.replace(" ","").length();g++) {
    458.                    double u=(int)Math.pow(10,t.replace(" ","").length()-g-1);
    459.                     wr=wr+u*Integer.parseInt(t.charAt(g)+"");
    460.                 }
    461.             sum=wr;
    462.             s=0;y=0;m=0;w=0;l=0;r=0;
    463.         }else if(e.getActionCommand().equals("Replay")) {  //重置
    464.             t="0                     ";
    465.             x=1;
    466.             m=0;
    467.             un=' ';
    468.             y=0;
    469.             s=0;
    470.             round=0;
    471.             w=0;
    472.             k=0;
    473.             sum=0;
    474.             r=0;
    475.             befor=0;
    476.             d=0;
    477.             l=0;
    478.         }else if(e.getActionCommand().equals("×")) {
    479.             if((x==15||x==14)&&(s==0&&y==0&&w==0)) {
    480.                 return;
    481.             }else if(m==1||l==1) {
    482.                 return;
    483.             }else 
    484.             {
    485.                 if(s==1||y==1||w==1){
    486.                     x=x-1;
    487.                 }
    488.                 StringBuilder strBuilder = new StringBuilder(t);
    489.                 strBuilder.setCharAt(x,'×');
    490.                 strBuilder.toString();
    491.                 t=strBuilder.toString();
    492.                 m=1;
    493.                 y=0;
    494.                 w=0;
    495.                 s=0;
    496.                 x=x+1;
    497.                 o=0;
    498.                 r=1;
    499.                 d=0;
    500.             }
    501.         }else if(e.getActionCommand().equals("÷")) {
    502.             if((x==15||x==14)&&(s==0&&y==0&&m==0)) {
    503.                 return;
    504.             }else if(w==1||l==1) {
    505.                 return;
    506.             }else 
    507.             {
    508.                 if(s==1||y==1||m==1){
    509.                     x=x-1;
    510.                 }
    511.                 StringBuilder strBuilder = new StringBuilder(t);
    512.                 strBuilder.setCharAt(x,'÷');
    513.                 strBuilder.toString();
    514.                 t=strBuilder.toString();
    515.                 w=1;
    516.                 m=0;
    517.                 y=0;
    518.                 s=0;
    519.                 x=x+1;
    520.                 o=0;
    521.                 d=0;
    522.                 r=1;
    523.             }
    524.         }else if(e.getActionCommand().equals("(")) {
    526.             if(x==15||x==14) {
    527.                 return;
    528.             }else if(l==1||(s==0&&y==0&&m==0&&w==0)) {
    529.                 return;
    530.             }else{
    531.                 StringBuilder strBuilder = new StringBuilder(t);
    532.                 strBuilder.setCharAt(x,'(');
    533.                 strBuilder.toString();
    534.                 t=strBuilder.toString();
    535.                 round=round+1;
    536.                 s=0;
    537.                 l=1;
    538.                 y=0;
    539.                 w=0;
    540.                 x=x+1;
    541.                 o=0;
    542.                 r=1;
    543.             }
    544.         }
    545.         else if(e.getActionCommand().equals(")")){
    546.             if(x==15){
    547.                 return;
    548.             }else if(round==0||t.charAt(x-1)=='(') {
    549.                 return;
    550.             }else if(s==1||y==1||m==1){
    551.                 x=x-1;
    552.             }
    553.                 StringBuilder strBuilder = new StringBuilder(t);
    554.                 strBuilder.setCharAt(x,')');
    555.                 strBuilder.toString();
    556.                 t=strBuilder.toString();
    557.                 s=0;
    558.                 d=1;
    559.                 round=round-1;
    560.                 l=0;
    561.                 y=0;
    562.                 w=0;
    563.                 x=x+1;
    564.                 o=0;
    565.                 r=1;
    566.             }
    567.         else if(e.getActionCommand().equals("DEL")) {
    568.             if(x!=0&&x!=1) {
    569.             x=x-1;
    570.             StringBuilder strBuilder = new StringBuilder(t);
    571.             strBuilder.setCharAt(x,' ');
    572.             strBuilder.toString();
    573.             t=strBuilder.toString();
    574.             }else if(x==1&&t.charAt(1)!=0) {
    575.                 x=x-1;
    576.             StringBuilder strBuilder = new StringBuilder(t);
    577.             strBuilder.setCharAt(x,'0');
    578.             strBuilder.toString();
    579.             t=strBuilder.toString();
    580.             x++;
    581.             }
    582.             System.out.println(x);
    583.         }
    584.         else if(e.getActionCommand().equals("end")){
    585.             System.exit(0);
    586.         }
    587.     }
    588. }