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大家好，我正在尝试在地图上的两点之间绘制折线，但是当我运行我的方法时，它会给出下面列出的错误。我已将错误范围缩小到：

canvas.drawLine(p1.x, p1.y, p2.x, p2.y, mPaint);

这是我的班级正在尝试绘制

package com.example.hellogooglemap;

class MyOverlay extends Overlay{
  private Projection projection;
  Paint mPaint;
  Context mContext;
  List<GeoPoint> gpList;


public MyOverlay(List<GeoPoint> geopointList, Context context) {
      super();
      mContext = context;
      gpList = geopointList;

      Paint   mPaint = new Paint();
      mPaint.setARGB(255, 10, 10, 255);
      mPaint.setAntiAlias(true);
      mPaint.setFakeBoldText(true); 

        //Toast.makeText(mContext, gpList.get(0).toString() , Toast.LENGTH_SHORT).show();
}

@Override
public void draw(Canvas canvas, MapView mapv, boolean shadow){  
    projection = mapv.getProjection();

    Point p1 = new Point();
    Point p2 = new Point();        

    projection.toPixels(gpList.get(0), p1);
    projection.toPixels(gpList.get(1), p2);

    canvas.drawLine(p1.x, p1.y, p2.x, p2.y, mPaint);        

    super.draw(canvas, mapv, shadow);
    }

}

这是错误

12-08 03:50:05.559: E/AndroidRuntime(1804): FATAL EXCEPTION: main
12-08 03:50:05.559: E/AndroidRuntime(1804): java.lang.NullPointerException
12-08 03:50:05.559: E/AndroidRuntime(1804):     at android.graphics.Canvas.drawLine(Canvas.java:876)
12-08 03:50:05.559: E/AndroidRuntime(1804):     at com.example.hellogooglemap.MyOverlay.draw(MyOverlay.java:56)
12-08 03:50:05.559: E/AndroidRuntime(1804):     at com.google.android.maps.Overlay.draw(Overlay.java:179)
12-08 03:50:05.559: E/AndroidRuntime(1804):     at com.google.android.maps.OverlayBundle.draw(OverlayBundle.java:42)
12-08 03:50:05.559: E/AndroidRuntime(1804):     at com.google.android.maps.MapView.onDraw(MapView.java:532)
12-08 03:50:05.559: E/AndroidRuntime(1804):     at android.view.View.draw(View.java:13707)
12-08 03:50:05.559: E/AndroidRuntime(1804):     at android.view.View.draw(View.java:13591)
12-08 03:50:05.559: E/AndroidRuntime(1804):     at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
12-08 03:50:05.559: E/AndroidRuntime(1804):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
12-08 03:50:05.559: E/AndroidRuntime(1804):     at android.view.View.draw(View.java:13589)
12-08 03:50:05.559: E/AndroidRuntime(1804):     at android.view.ViewGroup.drawChild(ViewGroup.java:2928)

任何帮助将不胜感激。我已经坚持了一段时间。

4

2 回答 2

1

在这一行：

Paint   mPaint = new Paint();

您正在分配给一个局部变量，而不是一个类。只需删除领先的“油漆”

mPaint = new Paint();
于 2012-12-31T10:13:47.820 回答
0

也许您可以尝试Google Maps Android API v2，因为 v1 已被弃用。

于 2012-12-31T10:05:40.567 回答