我知道这个问题已经被问过其他时间了，但我无法解决我的问题！
我创建自己的视图（RadarView），扩展视图。但是id没有更新！我尝试使用“invalidate()”和“postInvalidate()”，但它们不起作用！
这是雷达视图的代码：
`公共类雷达视图扩展视图{
private HashMap<Integer, RadarData> allNodes;
private int myId;
private double distance=0.0; //in degree
private double meeterDistance =0.0; // in meeters
private Paint paint,node,nodeText;
public RadarView(Context context, HashMap<Integer,RadarData> allNodes, int myId){
super(context);
this.allNodes = allNodes;
this.myId=myId;
paint = new Paint();
paint.setStyle(Paint.Style.STROKE);
paint.setAntiAlias(true);
paint.setColor(Color.GREEN);
node = new Paint();
node.setStyle(Paint.Style.FILL);
node.setAntiAlias(true);
node.setColor(Color.GREEN);
nodeText = new Paint();
nodeText.setStyle(Paint.Style.STROKE);
nodeText.setAntiAlias(true);
nodeText.setColor(Color.BLACK);
}
@Override protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//here we draw the radar
canvas.drawCircle(canvas.getWidth()/2, canvas.getHeight()/2, canvas.getWidth()/8, paint);
canvas.drawCircle(canvas.getWidth()/2, canvas.getHeight()/2, canvas.getWidth()/4, paint);
canvas.drawCircle(canvas.getWidth()/2, canvas.getHeight()/2, canvas.getWidth()/2.7f, paint);
canvas.drawCircle(canvas.getWidth()/2, canvas.getHeight()/2, canvas.getWidth()/2, paint);
canvas.drawLine(canvas.getWidth()/2, 0, canvas.getWidth()/2, canvas.getHeight(), paint);
canvas.drawLine(0, canvas.getHeight()/2, canvas.getWidth(), canvas.getHeight()/2, paint);
canvas.drawLine(canvas.getWidth() - canvas.getWidth()/4, canvas.getHeight()/10, canvas.getWidth() - canvas.getWidth()/4 +canvas.getWidth()/8, canvas.getHeight()/10, paint);
//then we add nodes in the view, if at least one exist
if(allNodes!=null){
RadarData me = allNodes.get(myId);
RadarData moreDistant = me;
Set<Integer> set = allNodes.keySet();
set.remove(myId);
for (Integer key : set){
RadarData element = allNodes.get(key);
//calculate if it's the more distant, in that case variable "moreDistant" is updated
if(distance<calculateDistance(element,me)){
distance=calculateDistance(element,me);
moreDistant=element;
}
}
for (Integer key : set){
drawNode(canvas,allNodes.get(key), me);
}
canvas.drawText("Unit: "+approximateDistance()/4+"degree", canvas.getWidth() - canvas.getWidth()/4, canvas.getHeight()/11, paint);
}
}
private double approximateDistance(){
int aux=(int) (distance*100);
return aux/100;
}
private void drawNode(Canvas canvas,RadarData element, RadarData me) {
int radius=canvas.getWidth()/2;
double x=element.getLongitude()-me.getLongitude();
double y=element.getLatitude() - me.getLatitude();
int xInTheView=(int)(radius + x*radius/distance);
int yInTheView=(int)(canvas.getHeight()/2 -y*radius/distance);
canvas.drawCircle(xInTheView, yInTheView, radius/10, node);
canvas.drawText(""+element.getId(), xInTheView, yInTheView, nodeText);
}
private double calculateDistance(RadarData element, RadarData me) {
return Math.hypot(element.getLatitude()-me.getLatitude(),
element.getLongitude()-me.getLongitude());
}
} `
在主 Activity 中，当 gps 位置发生变化时我调用它：
private void updateRadarView(Location location) {
if(location!=null){
RadarData newState= new RadarData(myId, location.getLatitude(), location.getLongitude(), RadarData.RUNNING);
allNodes = connectionHandler.request(newState);
radarView = new RadarView(this,allNodes,myId);
setContentView(radarView);
}
}
如您所见，我重新创建了radarView，然后使用setContentView 对其进行了更新，但我认为这不是一个好的解决方案。任何想法？