这样的题目你会编吗，你会改我的错吗

Question

import java.awt.*;
import javax.swing.*;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
private class WangPeng extends JFrame implements CaretListener
{ private JTextField text_1,text_2,text_3;
  private JComboBox combox_char;
  int i;
  public WangPeng(Object calculate[])  
  {super("整数的算术运算");
this.setBounds(300,240,234,300);
this.setBackground(java.awt.Color.lightGray);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.getContentPane().setLayout(new FlowLayout());text_1=new JTextField ("");
this.getContentPane().add(text_1);
combox_char=new JComboBox(calculate);
this.getContentPane().add(combox_char);
text_2=new JTextField ("");
this.getContentPane().add(text_2);
text_2.addCaretListener(this);
this.getContentPane().add(new JLabel("="));
text_1=new JTextField ("");
this.getContentPane().add(text_3);
this.setVisible(true);
}
public void caretUpdate(CaretEvent e)
{if(e.getSource()==text_2)
i=combox_char.getSelectedIndex();
  text_3.getText()=text_2.getText()+"calculate[i]"+text_1getText();
}
public static void main(String args[])
{ Object calculate[]={"+","-","*","/"};
  new WangPeng(calculate[]);
}}
就是一个标签作为=，三个文本框中有两个是作为输入整数 ，另一个作为答案，中间有一个组合框里面有— + * 、/我到底拿错了

Answer 1

错误还挺多的，比方说，以上代码中那行应该写作
new WangPeng(calculate);

Answer 2

import java.awt.*;
import javax.swing.*;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
public class WangPeng extends JFrame implements CaretListener
{
    private JTextField text_1,text_2,text_3;
    private JComboBox combox_char;
    private Object[] calculate;
    int i;
    public WangPeng(Object calculate[])
    {
        super("整数的算术运算");
        this.calculate = calculate;        this.setBounds(300,240,234,300);
        this.setBackground(java.awt.Color.lightGray);
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.getContentPane().setLayout(new FlowLayout());        text_1 = new JTextField (10);
        this.getContentPane().add(text_1);
        combox_char=new JComboBox(calculate);
        this.getContentPane().add(combox_char);        text_2 = new JTextField (10);
        this.getContentPane().add(text_2);
        text_2.addCaretListener(this);
        this.getContentPane().add(new JLabel("="));
        text_3 = new JTextField (10);
        this.getContentPane().add(text_3);
        this.setVisible(true);
    }
    public void caretUpdate(CaretEvent e)
    {
        if(e.getSource()==text_2)
            i=combox_char.getSelectedIndex();
        text_3.setText(text_2.getText() + calculate[i] + text_1.getText());
    }
    public static void main(String args[])
    {
        Object[] calculate = {"+","-","*","/"};
        new WangPeng(calculate);
    }
}
改掉了错误

Answer 3

但是这样的text_3没有结果，只有一个表达式，不能显示其结果啊

Answer 4

想出结果，自己根据+ - x /不同选择，在caretUpdate方法中给出不同的计算就OK了。
如
    public void caretUpdate(CaretEvent e)
    {
        if(e.getSource()==text_2)
            i=combox_char.getSelectedIndex();
        int result;
        try{
          int a = Integer.parseInt(text_1.getText());
          int b = Integer.parseInt(text_2.getText());
          if (i==0) result = a+b;
          else if (i==1) result = a-b;
          else if (i==2) result = a*b;
          else result = a/b;
          text_3.setText(result);
        }catch(Exception e){}
    }

Answer 5

小问题订正：
text_3.setText("" + result);
} catch (Exception e2) {}

Answer 6

修改完后效果import java.awt.*;
import javax.swing.*;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
public class WangPeng extends JFrame implements CaretListener
{
private JTextField text_1,text_2,text_3;
private JComboBox combox_char;
int i;
public WangPeng(Object calculate[])
{
super("整数的算术运算");
this.setBounds(300,240,234,300);
this.setBackground(java.awt.Color.lightGray);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.getContentPane().setLayout(new FlowLayout()); text_1=new JTextField ("");
this.getContentPane().add(text_1);
combox_char=new JComboBox(calculate);
this.getContentPane().add(combox_char); text_2=new JTextField ("");
this.getContentPane().add(text_2);
text_2.addCaretListener(this);
this.getContentPane().add(new JLabel("="));
text_3=new JTextField ("");
this.getContentPane().add(text_3);
this.setVisible(true);
}
public void caretUpdate(CaretEvent e)
{
if(e.getSource()==text_2)
i=combox_char.getSelectedIndex();
text_3.setText(text_2.getText() + "calculate[i]" + text_1.getText());
}
public static void main(String args[])
{
Object calculate[]={"+","-","*","/"};
new WangPeng(calculate);
}
}

Answer 7

这个题目是实现加减乘除的，要实现text_3的结果出来，不是表达式啊

Answer 8

import java.awt.*;
import javax.swing.*;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
import javax.swing.event.DocumentListener;
import java.text.NumberFormat;
import javax.swing.event.DocumentEvent;
import java.awt.event.ItemListener;
import java.awt.event.ItemEvent;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
public class WangPeng extends JFrame
{
    private static final String[] calculate = {"+","-","*","/"};
    private JFormattedTextField text_1,text_2,text_3;
    private NumberFormat formatter = NumberFormat.getIntegerInstance();
    private JComboBox combox_char;    public WangPeng()
    {
        super("整数的算术运算");        this.setBackground(java.awt.Color.lightGray);
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.getContentPane().setLayout(new FlowLayout());        text_1 = new JFormattedTextField(formatter);
        text_1.setColumns(10);
        text_1.setValue(Long.valueOf(0));
        this.getContentPane().add(text_1);
        combox_char=new JComboBox(calculate);
        this.getContentPane().add(combox_char);        text_2 = new JFormattedTextField (formatter);
        text_2.setValue(Long.valueOf(0));
        text_2.setColumns(10);
        this.getContentPane().add(text_2);
        this.getContentPane().add(new JLabel("="));
        text_3 = new JFormattedTextField (formatter);
        text_3.setColumns(10);
        text_3.setEditable(false);
        this.getContentPane().add(text_3);
        this.pack();
        this.setVisible(true);
        xxxxxxx();
    }    private void xxxxxxx(){
        FocusListener listener = new FocusListener(){
                @Override
                public void focusGained(FocusEvent e){
                    compute();
                }
                @Override
                public void focusLost(FocusEvent e){
                    compute();
                }
            };
        text_1.addFocusListener(listener);
        text_2.addFocusListener(listener);
        text_3.addFocusListener(listener);
        combox_char.addItemListener(new ItemListener(){
                public void itemStateChanged(ItemEvent e){
                    compute();
                }
            });
    }    private void compute(){
        long n1 = ((Long)text_1.getValue()).longValue();
        long n2 = ((Long)text_2.getValue()).longValue();
        switch (combox_char.getSelectedIndex()) {
        case 0:
            text_3.setValue(Long.valueOf(n1+n2));
            break;
        case 1:
            text_3.setValue(Long.valueOf(n1-n2));
            break;
        case 2:
            text_3.setValue(Long.valueOf(n1*n2));
            break;
        case 3:
            if (n2 != 0) {
                text_3.setValue(Long.valueOf(n1/n2));
            }
            break;
        default:
            break;
        }
    }    public static void main(String args[])
    {
        java.awt.EventQueue.invokeLater(new java.lang.Runnable(){
                @Override public void run(){
                    new WangPeng();
                }
            });
    }
}

Answer 9

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;import javax.swing.*;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
public class WangPeng extends JFrame implements CaretListener
{ 
private static final long serialVersionUID = 1L;
private JTextField text_1,text_2,text_3;
private JComboBox combox_char;
int i;
public WangPeng(Object calculate[])   
{
super("整数的算术运算");
this.setBounds(300,240,534,100);
this.setBackground(java.awt.Color.lightGray);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.getContentPane().setLayout(new FlowLayout()); text_1=new JTextField (10);
text_1.addCaretListener(this);
this.getContentPane().add(text_1);
combox_char=new JComboBox(calculate);
combox_char.addActionListener(new ActionListener() {

@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
if(text_2.getText().length()>0){
try {
int index=combox_char.getSelectedIndex();
int result=0;
switch(index){
case 0:result=Integer.parseInt(text_1.getText())+Integer.parseInt(text_2.getText());break;
case 1:result=Integer.parseInt(text_1.getText())-Integer.parseInt(text_2.getText());break;
case 2:result=Integer.parseInt(text_1.getText())*Integer.parseInt(text_2.getText());break;
case 3:result=Integer.parseInt(text_1.getText())/Integer.parseInt(text_2.getText());break;
}
text_3.setText(""+result);
} catch (Exception e2) {
// TODO: handle exception
JOptionPane.showMessageDialog(null, "输入的数字有误!");
text_2.setText("1");
}
}
}
});
this.getContentPane().add(combox_char); text_2=new JTextField (10);
this.getContentPane().add(text_2);
text_2.addCaretListener(this);
this.getContentPane().add(new JLabel("="));
text_3=new JTextField (10);
this.getContentPane().add(text_3);
this.setVisible(true);
}
public void caretUpdate(CaretEvent e)
{
if(text_2.getText().length()>0&&(e.getSource()==text_2||e.getSource()==text_1)){
try {
int index=combox_char.getSelectedIndex();
int result=0;
switch(index){
case 0:result=Integer.parseInt(text_1.getText())+Integer.parseInt(text_2.getText());break;
case 1:result=Integer.parseInt(text_1.getText())-Integer.parseInt(text_2.getText());break;
case 2:result=Integer.parseInt(text_1.getText())*Integer.parseInt(text_2.getText());break;
case 3:result=Integer.parseInt(text_1.getText())/Integer.parseInt(text_2.getText());break;
}
text_3.setText(""+result);
} catch (Exception e2) {
// TODO: handle exception
JOptionPane.showMessageDialog(null, "输入的数字有误!");
text_2.setText("1");
}
}
}
public static void main(String args[])
{ 
Object[] calculate={"+","-","*","/"};
new WangPeng(calculate);
}
}
楼主我帮你改好了 几乎没什么大的改动   而且text_3能显示结果