我在imagepanel中用drawstring()方法显示一个字符串，但是当我鼠标移动后
字符串就消失了？是否应该调用repaint()?repaint()有什么用？谢谢！！！

drawstring() 应写在　paint()中

应该调用repait()：
 public void init(){
   repaint();
}
 

在paint方法中使用drawString然后不论何时更新需显示的内容都要调用repaint
不过你的情况是不用调用repaint的

如果是继承awt中的Panel，将drawString()写在paint中，重载update方法：
public void update(Graphics g) {
  paint(g);
}
可防止闪烁。如果是JPanel就不必。

因为Panel中update方法是先擦后画，有闪烁。而JPanel中用双缓冲画。

// Properties

 

              /**

               * Paints this component using the given graphics context.

     * This is a standard Java AWT method which typically gets called

     * by the AWT to handle painting this component. It paints this component

     * using the given graphics context. The graphics context clipping region

     * is set to the bounding rectangle of this component and its [0,0]

     * coordinate is this component's top-left corner.

     *

     * @param g the graphics context used for painting

     * @see java.awt.Component#repaint

     * @see java.awt.Component#update

               */

              public void paint(Graphics g)

              {

                            Dimension dim = size();

                            if (image != null)

                            {

                                          int imageWidth = image.getWidth(this);

                                          int imageHeight = image.getHeight(this);

                                          switch(imageStyle)

                                          {

                                                        default:

                                                        case IMAGE_TILED:

                                                        {

                                                                      //Calculate number of images that should be drawn horizontally

                                                                      int numHImages = dim.width / imageWidth;

 

                                                                      //Don't forget remainders

                                                                      if (dim.width % imageWidth != 0)

                                                                                    numHImages++;

 

                                                                      //Calculate number of images that should be drawn vertically

                                                                      int numVImages = dim.height / imageHeight;

 

                                                                      //Don't forget remainders

                                                                      if (dim.height % imageHeight != 0)

                                                                                    numVImages++;

 

                                                                      int h;

                                                                      int v = 0;

                                                                      for (int vCount = 0;vCount 

    

 

请问repaint()延迟问题？