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我是编程的初学者...所以也许这个问题听起来很有趣。 我在MainActivity内部创建一个新的CanvasView时遇到了问题,因为它在其括号内写了一些东西。 这里是我的MainActivity:创建新的CanvasView
public class MainActivity extends AppCompatActivity {
CanvasView myView;
@Override
protected void onCreate(Bundle savedInstanceState) {
//the line below doesnt work
myView = new CanvasView();
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void button1(View v){
CanvasView.l = 400;
myView.invalidate();
}
}
这里是我CanvasView:
public class CanvasView extends View{
Paint paint = new Paint();
static int l = 500;
public CanvasView (Context context, AttributeSet attrs) {
super(context);
paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(Color.GREEN);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeWidth(10);
}
@Override
public void onDraw(final Canvas canvas) {
canvas.drawLine(100,100,l,100,paint);
}
}
我真的不明白是什么你的意思是你的第一行:“super.onCreate方法。” – nok4