调了一天没调对，是drawImage问题，说是空指针
错误：Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at mapDraw.pathDraw(mapDraw.java:127)
是说图片空指针，但是，上面一样的用法却是可以画图的。
下面g.drawImage(car, i.x, i.y, x, y, null);这句话错了；
import java.awt.Color; public class mapDraw extends JPanel {/**
*
*/
private static final long serialVersionUID = 1L;
private Path sp=new Path();
private Vector path = new Vector();
private boolean[][] map = new boolean[10][10];
private int xx;
private int yy;
//private int [][]b;
public mapDraw(int xx2, int yy2) {
// TODO Auto-generated constructor stub
xx=xx2;
yy=yy2;
}public void setMap() {
int m, n;
int i;
int w, h;for (m = 0; m <= 9; m++) {
for (n = 0; n <= 9; n++) {
map[m][n] = false; // 初始化，false表示路通；true表示障碍；，1表示最短路径 }
}
for (i = 0; i < 10; i++) // 设置10个障碍
{
w = (int) (Math.random() * 10);
h = (int) (Math.random() * 10);
//b[0][i]=w;
//b[1][i]=h;
map[w][h] = true; // 设置为障碍
if (map[0][0] == true)//因为(0，0)是起始点，不能设置成障碍。
map[0][0] = false;
}
}public boolean[][] getMap() {
return map;
}/**
* Create the panel.
*/
public void draw() {
Graphics g = getGraphics();
int m, n;
// 加载地图背景
Image image = new ImageIcon(getClass().getResource("/image/map2.jpg")).getImage();
g.drawImage(image, 0, 0, 450, 500, null);
// 加载地图网格
int x = this.getSize().width / 10;
int y = this.getSize().height / 10;for (m = 0; m < 10; m++) {
for (n = 0; n < 10; n++) {
g.setColor(Color.black);
g.drawRect(x * m, y * n, x, y);
}
}
//加载小车
//Image car = new ImageIcon(getClass().getResource("/image/car.jpg")).getImage();
//g.drawImage(car, 0, 0, x, y, this);
// 随机添加加障碍
for (m = 1; m < 10; m++)//不画边界
for (n = 0; n < 10; n++) {
if (map[m][n] == true) {
Image bar = new ImageIcon(getClass().getResource("/image/b0.jpg")).getImage();
g.drawImage(bar, x * m, y * n, x, y, null);
}
}
//画路径
/*for (m = 0; m < 10; m++)//不画边界
for (n = 0; n < 10; n++) {
if (map[m][n] == false) {
Image car = new ImageIcon(getClass().getResource("/image/car.jpg")).getImage();
g.drawImage(car, x * m, y * n, x, y, this);
}
}
*/
}
public void pathDraw(){
//找路径，画路径
Graphics g = getGraphics();
Image car = new ImageIcon(getClass().getResource("/image/c.jpg")).getImage();
int x = this.getSize().width / 10;
int y = this.getSize().height / 10;
sp.setMap(map, 10, 10);
sp.calcPath(0, 0, xx, yy);
System.out.print(path.isEmpty());
path=sp.getPath();
for(Point i:path){
g.drawImage(car, i.x, i.y, x, y, null);
}
}
}
