不懂

先画出界面，再加上事件监听就哦了

杀了我吧

你以为我会跟你说，这个在android下写的话，也就几分的事情吗

昨天刚写一个，要的话留个邮箱，我发给你……

我说我忘了，你信么

首先要判断两个输入框里面是否有小数点，如果有小数点就转成double类型，像你现在这样就会出现错误的

你类型没转换吧。

楼主说话可以一直没逗号我表示很困惑

这是我自己做的计算机源代码 希望对你有帮助
package jj; import java.awt.event.ActionEvent;
import java.awt.event.ActionListener; import javax.swing.JButton;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextArea; public class jisuanji extends JFrame{
private JTextArea text_1,text_2,text_3,text_4,text_5,text_6,text_7,text_8,text_dengyu1,text_dengyu2,text_dengyu3,text_dengyu4;
private JLabel label_add,label_jian,label_chu,label_chen,label_beijing;
private JButton button_dengyu1,button_dengyu2,button_dengyu3,button_4;
public jisuanji() {
setSize(315, 350);
setTitle("计算机");
setLayout(null);
add();
setVisible(true);
}
public void add(){
label_beijing=new JLabel();
label_beijing.setBounds(0, 0, 315, 350);
label_beijing.setLayout(null);
add(label_beijing);
//
text_1 =new JTextArea();
text_1.setBounds(10, 30, 60, 20);
label_beijing.add(text_1);
label_add =new JLabel("+");
label_add.setBounds(80, 30, 20, 20);
label_beijing.add(label_add);
//
text_2 =new JTextArea();
text_2.setBounds(100, 30, 60, 20);
label_beijing.add(text_2);
//
button_dengyu1 =new JButton("=");
button_dengyu1.setBounds(170, 30, 50, 20);
button_dengyu1.addActionListener(new ActionListener(){ @Override
public void actionPerformed(ActionEvent e) {
double a;
double b;
try {
String c=text_1.getText();
String d=text_2.getText();
a=Double.parseDouble(c);
b=Double.parseDouble(d);
String add=Double.toString(a+b);
String num=add.substring(add.indexOf("."));
if(num.lastIndexOf("0")==1&&num.lastIndexOf("0")==(num.length()-1)){
add=add.substring(0,add.indexOf("."));
}
System.out.println(num);
System.out.println(add);
text_dengyu1.setText(add);
} catch (RuntimeException e1) {
JOptionPane.showMessageDialog(null, "对不起只能为数字");
return;
}
}
});
label_beijing.add(button_dengyu1);
text_dengyu1 =new JTextArea();
text_dengyu1.setBounds(230, 30, 60, 20);
text_dengyu1.setKeymap(null);
label_beijing.add(text_dengyu1);
text_3 =new JTextArea();
text_3.setBounds(10, 70, 60, 20);
label_beijing.add(text_3);
label_jian =new JLabel("-");
label_jian.setBounds(80, 70, 20, 20);
label_beijing.add(label_jian);
text_4 =new JTextArea();
text_4.setBounds(100, 70, 60, 20);
label_beijing.add(text_4);
button_dengyu2 =new JButton("=");
button_dengyu2.setBounds(170, 70, 50, 20);
button_dengyu2.addActionListener(new ActionListener(){ @Override
public void actionPerformed(ActionEvent e) {
double a;
double b;
try {
String c=text_3.getText();
String d=text_4.getText();
a=Double.parseDouble(c);
b=Double.parseDouble(d);
String add=Double.toString(a-b);

String num=add.substring(add.indexOf("."));
if(num.lastIndexOf("0")==1&&num.lastIndexOf("0")==(num.length()-1)){
add=add.substring(0,add.indexOf("."));
}
System.out.println(num);
System.out.println(add);
text_dengyu2.setText(add);
} catch (RuntimeException e1) {
JOptionPane.showMessageDialog(null, "对不起只能为数字");
return;
}
}
});
label_beijing.add(button_dengyu2);
text_dengyu2 =new JTextArea();
text_dengyu2.setBounds(230, 70, 60, 20);
text_dengyu2.setKeymap(null);
label_beijing.add(text_dengyu2);
text_5 =new JTextArea();
text_5.setBounds(10, 110, 60, 20);
label_beijing.add(text_5);
label_chen =new JLabel("*");
label_chen.setBounds(80, 110, 20, 20);
label_beijing.add(label_chen);
text_6 =new JTextArea();
text_6.setBounds(100, 110, 60, 20);
label_beijing.add(text_6);
button_dengyu3 =new JButton("=");
button_dengyu3.setBounds(170, 110, 50, 20);
button_dengyu3.addActionListener(new ActionListener(){ @Override
public void actionPerformed(ActionEvent e) {
double a;
double b;
try {
String c=text_5.getText();
String d=text_6.getText();
a=Double.parseDouble(c);
b=Double.parseDouble(d);
String add=Double.toString(a*b);
String num=add.substring(add.indexOf("."));
if(num.lastIndexOf("0")==1&&num.lastIndexOf("0")==(num.length()-1)){
add=add.substring(0,add.indexOf("."));
}
System.out.println(num);
System.out.println(add);
text_dengyu3.setText(add);
} catch (RuntimeException e1) {
JOptionPane.showMessageDialog(null, "对不起只能为数字");
return;
}
}
});
label_beijing.add(button_dengyu3);
text_dengyu3 =new JTextArea();
text_dengyu3.setBounds(230, 110, 60, 20);
text_dengyu3.setKeymap(null);
label_beijing.add(text_dengyu3);
text_7 =new JTextArea();
text_7.setBounds(10,150, 60, 20);
label_beijing.add(text_7);
label_chu =new JLabel("/");
label_chu.setBounds(80, 150, 20, 20);
label_beijing.add(label_chu);
text_8 =new JTextArea();
text_8.setBounds(100, 150, 60, 20);
label_beijing.add(text_8);
button_dengyu3 =new JButton("=");
button_dengyu3.setBounds(170, 150, 50, 20);
button_dengyu3.addActionListener(new ActionListener(){ @Override
public void actionPerformed(ActionEvent e) {
double a;
double b;
try {
String c=text_7.getText();
String d=text_8.getText();
a=Double.parseDouble(c);
b=Double.parseDouble(d);
String add=Double.toString(a/b);
String num=add.substring(add.indexOf("."));
if(num.lastIndexOf("0")==1&&num.lastIndexOf("0")==(num.length()-1)){
add=add.substring(0,add.indexOf("."));
}
System.out.println(num);
System.out.println(add);
text_dengyu4.setText(add);
} catch (RuntimeException e1) {
JOptionPane.showMessageDialog(null, "对不起只能为数字");
return;
}
}
});
label_beijing.add(button_dengyu3);
text_dengyu4 =new JTextArea();
text_dengyu4.setBounds(230, 150, 60, 20);
text_dengyu4.setKeymap(null);
label_beijing.add(text_dengyu4);
}
public static void main(String[] args) {
new jisuanji();
}
}

wokao 求整段代码的有人回复 我就问下完善复选框显示问题的没人回答