Question

我已经在几天内遇到问题，到目前为止无法找到问题的解决方案。我有两节课： - StartActivity扩展了Activity - TimeGraphView扩展了SurfaceView

我想要实现的是将TimeGraphView中的动态按钮添加到另一个视图（LinearLayout）。这样做是想用FindViewById（）在TimeGraphView中获取LinearLayout但是它返回null，它应该因为我在TimeGraphView中调用它而不是在root元素中我使用setContentView（）;

所以我的问题是如何从自定义视图级别动态添加按钮到另一个视图。

我的代码：

public class StartActivity extends Activity {

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.time_graph);

        LinearLayout layout = (LinearLayout) this.findViewById(R.id.TimeGraphLayout);
        //here I can add button but it's not what I want
    }
}

和......

public class TimeGraphView extends SurfaceView implements SurfaceHolder.Callback, Runnable {

    public TimeGraphView(Context context) {
        super(context);
    }

    public TimeGraphView(Context context, AttributeSet set) {
        super(context, set);
    }

    public TimeGraphView(Context context, AttributeSet set, int arg) {
        super(context, set, arg);
    }

    public void run() {
        while (run) {
            if (something) {
                LinearLayout layout = (LinearLayout) findViewById(R.id.TimeGraphLayout);
                if (layout != null) {
                    Button button = new Button(context);
                    button.setText(text);
                    layout.addView(button);
                } else {
                    Log.e("TimeGraphView", "TimeGraphLayout is null");
                    //and "layout" is always null and that's the problem ;(
                }
            }
        }
    }
}

...和我的XML

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/TimeGraphRootLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <HorizontalScrollViewa
        android:id="@+id/TimeGraphPanel"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <LinearLayout
            android:id="@+id/TimeGraphLayout"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal" />
    </HorizontalScrollView>

    <my.package.TimeGraphView
        android:id="@+id/TimeGraphChart"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

Answer 1

你不能以这种方式使用它。如果你添加一个根元素Linearlayout并引用它，那么它可能会起作用。如果你想获得TimeGraphLayout类：

 TimeGraphView layout = (TimeGraphView) findViewById(R.id.TimeGraphLayout);
 setContentView(layout);

您执行此操作的原始方式无效，因为TimeGraphView不是LinearLayout

View中的findViewById用法

1 个答案: