我是Android编程新手,我试图在屏幕上画一个圆圈。最后,我想让圈子四处移动。但是现在我一直无法让圆圈画出来。当我运行代码时,它给了我一个错误:
"尝试调用虚拟方法' long android.graphics.Paint.getNativeInstance()'在null"
我的代码:
package com...
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new MyView(this));
}
class MyView extends View {
private Bitmap b;
public Paint p;
public MyView(Context context) {
super(context);
Paint p = new Paint();
p.setColor(Color.GREEN);
b = Bitmap.createBitmap(100, 100, Bitmap.Config.ARGB_8888);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawCircle(50, 50, 10, p);
}
}
}
答案 0 :(得分:1)
您的代码存在问题
v0.10.30