Java开发网 - 求助！！！请看下面源程序，编译没有错。运行时会报转换错误~急~！！！谢谢

Topic: 求助！！！请看下面源程序，编译没有错。运行时会报转换错误~急~！！！谢谢

1.求助！！！请看下面源程序，编译没有错。运行时会报转换错误~急~！！！谢谢

Posted by: 22750124
Posted on: 2005-07-15 23:12

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

class RectangleCurvePanel extends JPanel
{
  Label tempx1Label=new Label();
  Label tempy1Label=new Label();
  Label tempx2Label=new Label();
  Label tempy2Label=new Label();

  public RectangleCurvePanel()
  {
    this.addMouseListener
    (
      new MouseAdapter()
      {
        public void mousePressed(MouseEvent e)
        {
          tempx1Label.setText(Integer.toString(e.getX()));
          tempy1Label.setText(Integer.toString(e.getY()));
        }
        public void mouseReleased(MouseEvent e)
        {
          tempx2Label.setText(Integer.toString(e.getX()));
          tempy2Label.setText(Integer.toString(e.getY()));
        }
      }
     Wink

;
  }

  int x1=Integer.parseInt(tempx1Label.getText());
  int y1=Integer.parseInt(tempy1Label.getText());
  int x2=Integer.parseInt(tempx2Label.getText());
  int y2=Integer.parseInt(tempy2Label.getText());
  int width=Math.abs(x1-x2);
  int hight=Math.abs(y1-y2);

  public void paintComponent(Graphics g)
  {
    if(x1<x2 && y1<y2)//右下方拉
    {
      g.drawRect(x1,y1,width,hight);
    }
    else
    {
      if(x1<x2 && y1>y2)//右上方拉
      {
        g.drawRect(x1,y2,width,hight);
      }
      else
      {
        if(x1>x2 && y1>y2)//左上拉
        {
          g.drawRect(x2,y2,width,hight);
        }
        else
        {
          if(x1>x2 && y1<y2)//左下拉
          {
            g.drawRect(x2,y1,width,hight);
          }
          else
          {
            System.out.println("不能画出矩开请重新拖~");
          }
        }
      }
    }
  }

}

class RectangleCurve extends JFrame
{
  public static void main(String[] args)
  {
    RectangleCurve xy=new RectangleCurve();
     RectangleCurvePanel f=new RectangleCurvePanel();
     JLabel titleLabel=new JLabel("Please drawing coordinate.");

    Container c=xy.getContentPane();

    c.add(f,BorderLayout.CENTER);
    c.add(titleLabel,BorderLayout.NORTH);

    xy.setSize(500,350);
    xy.setVisible(true);
  }
}

2.Re:求助！！！请看下面源程序，编译没有错。运行时会报转换错误~急~！！！谢谢 [Re: 22750124]	Copy to clipboard
Posted by: Jayzz Posted on: 2005-07-17 16:17 int x1=Integer.parseInt(tempx1Label.getText()); int y1=Integer.parseInt(tempy1Label.getText()); int x2=Integer.parseInt(tempx2Label.getText()); int y2=Integer.parseInt(tempy2Label.getText()); 这里会出错---NumberFormatException. 因为这些Label中没有合适的数据. 合适是指能够被转换为int型.

3.Re:求助！！！请看下面源程序，编译没有错。运行时会报转换错误~急~！！！谢谢 [Re: 22750124]	Copy to clipboard
Posted by: Jayzz Posted on: 2005-07-17 16:22 事实上, 你没有必要设置这几个Label, 完全可以使用这些int. 例如: tempx1Label.setText(Integer.toString(e.getX())); tempy1Label.setText(Integer.toString(e.getY())); 改为: x1 = e.getX(); y1 = e.getY();

4.Re:求助！！！请看下面源程序，编译没有错。运行时会报转换错误~急~！！！谢谢 [Re: 22750124]	Copy to clipboard
Posted by: 22750124 Posted on: 2005-07-17 19:42 Label tempx1Label=new Label(); Label tempy1Label=new Label(); Label tempx2Label=new Label(); Label tempy2Label=new Label(); Label中应该给初始值，不给当然会报错，如下面 Label tempx1Label=new Label("1"); Label tempx1Label=new Label("2"); Label tempx1Label=new Label("3"); Label tempx1Label=new Label("4");