java - 如何使用在另一个类中声明的数组

Question

我是 Java 新手。这是我的代码。我在onCreate()中创建了一个数组，如何在onDraw()中使用它？谢谢!

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    int Circle_list[] = { Color.BLACK, 20, 20, 50 };
}

private class MyViewCircle extends View {

    public MyViewCircle(Context context) {
        super(context);

        // TODO Auto-generated constructor stub
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        super.onDraw(canvas);
        Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setColor(Color.WHITE);
        canvas.drawCircle(Circle_list[1], Circle_list[2], Circle_list[3], paint);
    }
}

Answer 1

目前，您的数组是仅在“onCreate”方法内部已知的局部变量。您必须通过将其定义为实例变量来更改其范围，以便 onDraw 能够访问它。

    private int[] Circle_list = null ;
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);         
        Circle_list = new int[] { Color.BLACK, 20, 20, 50 };     
    }  
    private class MyViewCircle extends View {          
        public MyViewCircle(Context context) {
            super(context);              
        // TODO Auto-generated constructor stub         
        }
        @Override
        protected void onDraw(Canvas canvas) {
           // TODO Auto-generated method stub
           super.onDraw(canvas);
           Paint paint = new Paint();
           paint.setAntiAlias(true);
           paint.setColor(Color.WHITE);
           canvas.drawCircle(Circle_list[1], Circle_list[2], Circle_list[3],
                paint);         
        }     
    }