Question

这是代码的java部分

public class MainActivity extends Activity
{
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }


    class surf extends View {

        public surf(Context c,AttributeSet as) {
            super(c,as);
        }

        protected void onDraw(Canvas canvas) {
            Paint p = new Paint();
            p.setColor(Color.MAGENTA);
            canvas.drawLine(20, 20,200, 20,p);
        }
    }
}

没有其他视图的资源文件

 <view
    class="tictac.Tictac.MainActivity$surf"
    android:id="@+id/graphics" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"/>
</LinearLayout>

它一打开就出现错误，我一直关注Android网站上的教程

Answer 1

试试这段代码。在这里，我将自己的视图添加为主视图。

public class MainActivity extends Activity
{
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(new surf(this));
    }

    class surf extends View {

        public surf(Context c)
        {
            super(c);
        }

        public surf(Context c,AttributeSet as) {
            super(c,as);
        }

        protected void onDraw(Canvas canvas) {
            Paint p = new Paint();
            p.setColor(Color.MAGENTA);
            canvas.drawLine(20, 20,200, 20,p);
        }
   }
}

或者您可以在XML中添加视图

<com.my.package.MyClass
    android:id="@+id/graphics" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"/>

无法使用视图在android中绘制一条线

1 个答案: