java图形问题~~~郁闷！！！：（

Question

最原始最简单的方法就是获得（mousedown）坐标（startx，starty），获得（mouseup）坐标（endx，endy），这就是矩形的对角坐标，然后根据公式算出其他两个点的坐标，再把他们连线画出来就行了

Answer 1

你想要那种应用的,applet或是application

Answer 2

里面有线，谢先，圆，把圆该一下
draw(Rectangle2D.DOUBLE);applet 你继承字japplet酒兴
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class Test extends JFrame{
  private JButton b1,b2,b3;
  private   Draw dr;
  public Test ()
  {
      dr =new Draw();
      b1 = new JButton("line");
      b1.addActionListener(
      new ActionListener(){
        public void actionPerformed(ActionEvent e)
        {
          dr.setDraw(e.getActionCommand());
          dr.repaint();
        }
      }
    );
     b2 = new JButton("oval");
     b2.addActionListener(
      new ActionListener(){
        public void actionPerformed(ActionEvent e)
        {
           dr.setDraw(e.getActionCommand());
           dr.repaint();
        }
      }
    );
    b3 = new JButton("xie");
    b3.addActionListener(
     new ActionListener(){
       public void actionPerformed(ActionEvent e)
       {
         dr.setDraw(e.getActionCommand());
         dr.repaint();
       }
     }
   );
     Container c = getContentPane();
     c.add(b1,BorderLayout.SOUTH);
     c.add(b2,BorderLayout.NORTH);
     c.add(b3,BorderLayout.WEST);
     c.add(dr,BorderLayout.CENTER);
     validate();
     show();
     setSize(200,200);
     repaint();
  }
  public static  void main(String args[])
  {
     Test t =new Test();
     t.addWindowListener(
       new WindowAdapter(){
         public void windowClosing(WindowEvent e)
         {
           System.exit(0);
         }
       }
    );
  }
}class Line {
   public int x0,y0,x1,y1;
}class Draw extends JPanel{
   Vector lines;
   Vector ovals ;
   Vector write;
   private String ss;
   protected  int x1,x2,y1,y2;
   Line cur,curo;   public Draw()
   {      lines = new Vector();
      ovals = new Vector();
      write = new Vector();
      setPreferredSize(new Dimension(150,100));
      setBackground(Color.white);
      addMouseListener( new MouseAdapter() {
         public void mousePressed(MouseEvent e) {
            if((cur == null)||(curo==null))
            {
                   cur = new Line();
                curo = new Line();
//                text = new Line();
            }
            if(ss=="line")
            {
            cur.x0 = e.getX();
            cur.y0 = e.getY();
            }
            else if(ss=="oval")
            {
            curo.x0 = e.getX();
            curo.y0 = e.getY();
            }
            else if(ss=="xie")//跟下一个程序对比这里
            {
                x1=e.getX();
                y1=e.getY();
            }//。
         }
         public void mouseReleased(MouseEvent e) {            if(ss=="line")
            {
              cur.x1 = e.getX();
              cur.y1 = e.getY();
              lines.add(cur);
              cur =null;
            }
            else if (ss=="oval")
           {
            curo.x1 = e.getX();
            curo.y1 = e.getY();
            ovals.add(curo);
            curo = null;
           }
        }
      });      addMouseMotionListener( new MouseMotionAdapter(){
         public void mouseDragged(MouseEvent e){
            if(ss =="line")
            {
            cur.x1 = e.getX();
            cur.y1 = e.getY();
            }
            else if(ss=="oval")
            {
            curo.x1 = e.getX();
            curo.y1 = e.getY();
            }            else if(ss == "xie")//跟下一个程序对比这里
            {
                Line text = new Line();
                text.x0 = x1;
                text.y0 = y1;
                text.x1 = e.getX();
                text.y1 = e.getY();
                x1=e.getX();
                y1=e.getY();
                write.add(text);
            }//。。//            else if(ss=="xie")//跟下一个程序对比这里
//            {
//              x2=e.getX();
//              y2=e.getY();
//            }//
            repaint();
          }
      });
  }
  public void setDraw(String s)
  {
     ss=s;
  }
  public void paintComponent(Graphics g) {
     super.paintComponent(g);     for(int i = 0;i<lines.size();i++){
        Line tmp = (Line)lines.elementAt(i);
        g.drawLine(tmp.x0, tmp.y0, tmp.x1, tmp.y1);
     }
     if(cur != null )
       g.drawLine(cur.x0,cur.y0,cur.x1,cur.y1);
      for(int i = 0;i<ovals.size();i++){
        Line tmpo = (Line)ovals.elementAt(i);
         g.drawOval(Math.min(tmpo.x0,tmpo.x1),Math.min(tmpo.y0,tmpo.y1),
        Math.abs(tmpo.x0-tmpo.x1),Math.abs(tmpo.y0-tmpo.y1));
     }
     if(curo != null )
       g.drawOval(Math.min(curo.x0,curo.x1),Math.min(curo.y0,curo.y1),
        Math.abs(curo.x0-curo.x1),Math.abs(curo.y0-curo.y1));
     for(int i = 0;i<write.size();i++){
       Line tmp = (Line)write.elementAt(i);
        g.drawLine(tmp.x0, tmp.y0, tmp.x1, tmp.y1);
     }
//        if(x1==-1 || y1==-1)////跟下一个程序对比这里。。
//      {
//
//        x1=x2;
//        y1=y2;
//      }
//      g.drawLine(x1,y1,x2,y2);//跟下一个程序对比这里
//
//      x1=x2;
//      y1=y2;//。
  }
}

Answer 3

把g.drawOval(Math.min(curo.x0,curo.x1),Math.min(curo.y0,curo.y1),
        Math.abs(curo.x0-curo.x1),Math.abs(curo.y0-curo.y1));
改成g.drawRect(Math.min(curo.x0,curo.x1),Math.min(curo.y0,curo.y1),
        Math.abs(curo.x0-curo.x1),Math.abs(curo.y0-curo.y1));就是矩形

Answer 4

JavaBoyCaoJi(老曹) 
怎么到处都有你！
还总是UP

Answer 5

以前做的作业， 你参考一下http://my.nbip.net/homepage/zhouB403/MyCode/2dDraw.exe