我想编一个计算器，现在只是考虑加法，为什么点击“=”时，文本框不会出现结果？
import java.awt.*;
import javax.swing.*;
import javax.swing.border.LineBorder;
import javax.swing.text.BadLocationException;
import java.awt.event.*;
public class JSQ extends JFrame implements ActionListener{
JButton[] an={null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null};
JTextField wbk1,wbk2;
String firstnum,secomenum,firstfh,secomefh;
double s1,s2;
boolean sign,sign2;
public static void main(String[] args){
JSQ a1=new JSQ();
}
public JSQ(){
an[0]=new JButton("0"); an[1]=new JButton("1");
an[2]=new JButton("2"); an[3]=new JButton("3");
an[4]=new JButton("4"); an[5]=new JButton("5");
an[6]=new JButton("6"); an[7]=new JButton("7");
an[8]=new JButton("8"); an[9]=new JButton("9");
an[10]=new JButton("+"); an[11]=new JButton("-");
an[12]=new JButton("*"); an[13]=new JButton("÷");
an[14]=new JButton("xn"); an[15]=new JButton("n√");
an[16]=new JButton("("); an[17]=new JButton(")");
an[18]=new JButton("DEL"); an[19]=new JButton("C");
an[20]=new JButton("."); an[21]=new JButton("=");
wbk1=new JTextField(20); wbk2=new JTextField(20);
firstnum=new String(""); secomenum=new String("");
firstfh=new String(""); secomefh=new String("");
sign=false; sign2=false;
for(int i=0;i<=21;i++){
an[i].setFont(new Font("宋体",Font.PLAIN,20));
an[i].setBorder(new LineBorder(Color.black));
}
this.setLayout(null);
wbk1.setSize(290,35);
wbk1.setLocation(20,30);
//wbq.setBorder(new LineBorder(Color.black));
wbk2.setSize(290,35);
wbk2.setLocation(20,64);
//wbk.setBorder(new LineBorder(Color.black));
for(int i=1;i<=20;i++){
an[i].setSize(65,45);
}
an[0].setSize(140,45);
an[21].setSize(65,100);
for(int i=16,n=20;i<=19;i++){
an[i].setLocation(n,130);
n+=75;
}
for(int i=12,n=20;i<=15;i++){
an[i].setLocation(n,185);
n+=75;
}
for(int i=7,n=20;i<=9;i++){
an[i].setLocation(n,240);
n+=75;
}
for(int i=4,n=20;i<=6;i++){
an[i].setLocation(n,295);
n+=75;
}
for(int i=1,n=20;i<=3;i++){
an[i].setLocation(n,350);
n+=75;
}
an[11].setLocation(245,240);
an[10].setLocation(245,295);
an[0].setLocation(20,405);
an[20].setLocation(170,405);
an[21].setLocation(245,350);
for(int i=0;i<=18;i++){
an[i].setForeground(Color.white);
an[i].setBackground(Color.gray);
}
an[19].setForeground(Color.red);
an[20].setForeground(Color.white);
an[21].setForeground(Color.white);
an[19].setBackground(Color.gray);
an[20].setBackground(Color.gray);
an[21].setBackground(Color.orange);
for(int i=0;i<=21;i++){
this.add(an[i]);
an[i].addActionListener(this);
}
an[0].setActionCommand("0"); an[1].setActionCommand("1");
an[2].setActionCommand("2"); an[3].setActionCommand("3");
an[4].setActionCommand("4"); an[5].setActionCommand("5");
an[6].setActionCommand("6"); an[7].setActionCommand("7");
an[8].setActionCommand("8"); an[9].setActionCommand("9");
an[10].setActionCommand("+"); an[11].setActionCommand("-");
an[12].setActionCommand("*"); an[13].setActionCommand("/");
an[14].setActionCommand("xn"); an[15].setActionCommand("n√");
an[16].setActionCommand("("); an[17].setActionCommand(")");
an[18].setActionCommand("DEL"); an[19].setActionCommand("C");
an[20].setActionCommand("."); an[21].setActionCommand("=");
this.add(wbk1);
this.add(wbk2);
this.setSize(335,500);
this.setLocation(500,200);
this.setTitle("计算器");
this.setIconImage((new ImageIcon("image/jsq.jpg")).getImage());
this.setResizable(false);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
}
public void actionPerformed(ActionEvent e){
for(int i=0;i<=9;i++){
if(e.getSource()==an[i]){
wbk1.setText(wbk1.getText()+Integer.toString(i));
String s=e.getActionCommand();
shuju(s);
}
}
if(e.getSource()==an[21]){
String s=e.getActionCommand();
fuhao(s);
Operator();
}
if(e.getSource()==an[10]){
sign=true;
wbk1.setText(wbk1.getText()+String.valueOf("+"));
//String s=e.getActionCommand();
//fuhao(s);
}//else if(e.getSource()==an[11]){
//wbk1.setText(wbk1.getText()+String.valueOf("-"));
//String s=e.getActionCommand();
//fuhao(s);
//}else if(e.getSource()==an[12]){
//wbk1.setText(wbk1.getText()+String.valueOf("*"));
//String s=e.getActionCommand();
//fuhao(s);
//}else if(e.getSource()==an[13]){
//wbk1.setText(wbk1.getText()+String.valueOf("÷"));
//String s=e.getActionCommand();
//fuhao(s);
//}else if(e.getSource()==an[14]){
//wbk1.setText(wbk1.getText()+String.valueOf("xn"));
//String s=e.getActionCommand();
//fuhao(s);
//}else if(e.getSource()==an[15]){
//wbk1.setText(wbk1.getText()+String.valueOf("n√"));
//String s=e.getActionCommand();
//fuhao(s);
//}else if(e.getSource()==an[16]){
//wbk1.setText(wbk1.getText()+String.valueOf("("));
//String s=e.getActionCommand();
//fuhao(s);
//}else if(e.getSource()==an[17]){
//wbk1.setText(wbk1.getText()+String.valueOf(")"));
//String s=e.getActionCommand();
//fuhao(s);
//}else if(e.getSource()==an[18]){
//wbk1.setText(wbk1.getText()+String.valueOf("DEL"));
//String s=e.getActionCommand();
//fuhao(s);
//}else if(e.getSource()==an[19]){
//wbk1.setText(wbk1.getText()+String.valueOf("C"));
//String s=e.getActionCommand();
//fuhao(s);
//}else if(e.getSource()==an[20]){
//wbk1.setText(wbk1.getText()+String.valueOf("."));
//}
}
public void shuju(String s){
if(sign=false){
firstnum +=s;
}else{
secomenum +=s;
}
if(firstnum!="" && secomenum!=""){
s1=new Double(firstnum).doubleValue();
s2=new Double(secomenum).doubleValue();
}
}
public void fuhao(String s){
if(sign=false){
firstfh=s;
}else{
secomefh=s;
}
}
public void Operator(){
if(firstfh.equals("+") && secomefh.equals("=")){
String s=String.valueOf(s1+s2);
wbk2.setText(s);
}
}
}
[解决办法]
修改了3个地方：楼主试试
import java.awt.*;
import javax.swing.*;
import javax.swing.border.LineBorder;
import javax.swing.text.BadLocationException;
import java.awt.event.*;
public class JSQ extends JFrame implements ActionListener {
JButton[] an = { null, null, null, null, null, null, null, null, null,
null, null, null, null, null, null, null, null, null, null, null,
null, null };
JTextField wbk1, wbk2;
String firstnum, secomenum, firstfh, secomefh;
double s1, s2;
boolean sign, sign2;
public static void main(String[] args) {
JSQ a1 = new JSQ();
}
public JSQ() {
an[0] = new JButton("0");
an[1] = new JButton("1");
an[2] = new JButton("2");
an[3] = new JButton("3");
an[4] = new JButton("4");
an[5] = new JButton("5");
an[6] = new JButton("6");
an[7] = new JButton("7");
an[8] = new JButton("8");
an[9] = new JButton("9");
an[10] = new JButton("+");
an[11] = new JButton("-");
an[12] = new JButton("*");
an[13] = new JButton("÷");
an[14] = new JButton("xn");
an[15] = new JButton("n√");
an[16] = new JButton("(");
an[17] = new JButton(")");
an[18] = new JButton("DEL");
an[19] = new JButton("C");
an[20] = new JButton(".");
an[21] = new JButton("=");
wbk1 = new JTextField(20);
wbk2 = new JTextField(20);
firstnum = new String("");
secomenum = new String("");
firstfh = new String("");
secomefh = new String("");
sign = false;
sign2 = false;
for (int i = 0; i <= 21; i++) {
an[i].setFont(new Font("宋体", Font.PLAIN, 20));
an[i].setBorder(new LineBorder(Color.black));
}
this.setLayout(null);
wbk1.setSize(290, 35);
wbk1.setLocation(20, 30);
// wbq.setBorder(new LineBorder(Color.black));
wbk2.setSize(290, 35);
wbk2.setLocation(20, 64);
// wbk.setBorder(new LineBorder(Color.black));
for (int i = 1; i <= 20; i++) {
an[i].setSize(65, 45);
}
an[0].setSize(140, 45);
an[21].setSize(65, 100);
for (int i = 16, n = 20; i <= 19; i++) {
an[i].setLocation(n, 130);
n += 75;
}
for (int i = 12, n = 20; i <= 15; i++) {
an[i].setLocation(n, 185);
n += 75;
}
for (int i = 7, n = 20; i <= 9; i++) {
an[i].setLocation(n, 240);
n += 75;
}
for (int i = 4, n = 20; i <= 6; i++) {
an[i].setLocation(n, 295);
n += 75;
}
for (int i = 1, n = 20; i <= 3; i++) {
an[i].setLocation(n, 350);
n += 75;
}
an[11].setLocation(245, 240);
an[10].setLocation(245, 295);
an[0].setLocation(20, 405);
an[20].setLocation(170, 405);
an[21].setLocation(245, 350);
for (int i = 0; i <= 18; i++) {
an[i].setForeground(Color.white);
an[i].setBackground(Color.gray);
}
an[19].setForeground(Color.red);
an[20].setForeground(Color.white);
an[21].setForeground(Color.white);
an[19].setBackground(Color.gray);
an[20].setBackground(Color.gray);
an[21].setBackground(Color.orange);
for (int i = 0; i <= 21; i++) {
this.add(an[i]);
an[i].addActionListener(this);
}
an[0].setActionCommand("0");
an[1].setActionCommand("1");
an[2].setActionCommand("2");
an[3].setActionCommand("3");
an[4].setActionCommand("4");
an[5].setActionCommand("5");
an[6].setActionCommand("6");
an[7].setActionCommand("7");
an[8].setActionCommand("8");
an[9].setActionCommand("9");
an[10].setActionCommand("+");
an[11].setActionCommand("-");
an[12].setActionCommand("*");
an[13].setActionCommand("/");
an[14].setActionCommand("xn");
an[15].setActionCommand("n√");
an[16].setActionCommand("(");
an[17].setActionCommand(")");
an[18].setActionCommand("DEL");
an[19].setActionCommand("C");
an[20].setActionCommand(".");
an[21].setActionCommand("=");
this.add(wbk1);
this.add(wbk2);
this.setSize(335, 500);
this.setLocation(500, 200);
this.setTitle("计算器");
this.setIconImage((new ImageIcon("image/jsq.jpg")).getImage());
this.setResizable(false);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
}
public void actionPerformed(ActionEvent e) {
for (int i = 0; i <= 9; i++) {
if (e.getSource() == an[i]) {
wbk1.setText(wbk1.getText() + Integer.toString(i));
String s = e.getActionCommand();
shuju(s);
}
}
if (e.getSource() == an[21]) {
String s = e.getActionCommand();
fuhao(s);
Operator();
}
if (e.getSource() == an[10]) {
wbk1.setText(wbk1.getText() + String.valueOf("+"));
String s=e.getActionCommand();//加上
fuhao(s);//加上
sign = true;//放后边
}// else if(e.getSource()==an[11]){
// wbk1.setText(wbk1.getText()+String.valueOf("-"));
// String s=e.getActionCommand();
// fuhao(s);
// }else if(e.getSource()==an[12]){
// wbk1.setText(wbk1.getText()+String.valueOf("*"));
// String s=e.getActionCommand();
// fuhao(s);
// }else if(e.getSource()==an[13]){
// wbk1.setText(wbk1.getText()+String.valueOf("÷"));
// String s=e.getActionCommand();
// fuhao(s);
// }else if(e.getSource()==an[14]){
// wbk1.setText(wbk1.getText()+String.valueOf("xn"));
// String s=e.getActionCommand();
// fuhao(s);
// }else if(e.getSource()==an[15]){
// wbk1.setText(wbk1.getText()+String.valueOf("n√"));
// String s=e.getActionCommand();
// fuhao(s);
// }else if(e.getSource()==an[16]){
// wbk1.setText(wbk1.getText()+String.valueOf("("));
// String s=e.getActionCommand();
// fuhao(s);
// }else if(e.getSource()==an[17]){
// wbk1.setText(wbk1.getText()+String.valueOf(")"));
// String s=e.getActionCommand();
// fuhao(s);
// }else if(e.getSource()==an[18]){
// wbk1.setText(wbk1.getText()+String.valueOf("DEL"));
// String s=e.getActionCommand();
// fuhao(s);
// }else if(e.getSource()==an[19]){
// wbk1.setText(wbk1.getText()+String.valueOf("C"));
// String s=e.getActionCommand();
// fuhao(s);
// }else if(e.getSource()==an[20]){
// wbk1.setText(wbk1.getText()+String.valueOf("."));
// }
}
public void shuju(String s) {
if (sign == false) {//== not =
firstnum += s;
} else {
secomenum += s;
}
if (!firstnum.equals("") && !secomenum.equals("")) {//用equals
s1 = new Double(firstnum).doubleValue();
s2 = new Double(secomenum).doubleValue();
}
}
public void fuhao(String s) {
if (sign == false) {//== not =
firstfh = s;
} else {
secomefh = s;
}
}
public void Operator() {
if (firstfh.equals("+") && secomefh.equals("=")) {
String s = String.valueOf(s1 + s2);
wbk2.setText(s);
}
}
}
