android - 无法将 View 添加到以编程方式添加的 ViewGroups

Question

我无法将 subview 添加到以编程方式添加的 ViewGroup。

首先，我创建一个 GroupView (_view) 并将其添加到背景 RelativeLayout (_root) 中，如下所示...

            _view = new ViewGroup(MainActivity.this) {
                @Override
                protected void onLayout(boolean b, int i, int i1, int i2, int i3) {
                }
            };

            _view.setBackgroundColor(0xFF00FF00);
            RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, 200);
            params.setMargins(10, 0, 10, 0);
            _view.setLayoutParams(params);
            _view.setTranslationX(0);
            _view.setTranslationY(positionY - 80);
            selectView(_view);

            _root.addView(_view);

            _view.setTag(R.string.viewID, "" + viewNum);
            _view.setTag(R.string.viewSelected, "" + 0);
            viewNum ++;

这很好用。然后我尝试像这样向新的 GroupView (_view) 添加一个 View ...

            ImageView dragIcon = new ImageView(MainActivity.this);
            dragIcon.setImageResource(R.drawable.drabicon);
            RelativeLayout.LayoutParams imgParams = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
            imgParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
            imgParams.setMargins(0,0,30,0);
            dragIcon.setLayoutParams(imgParams);
            dragIcon.setTranslationY(_view.getTranslationY());

            _view.addView(dragIcon); // This Is What I Want, But This Doesn't Work.

            //_root.addView(dragIcon); // Don't Want This, But This Works.

但是它没有被添加，或者它不可见等等。现在，如果我像这样使用 Background RelativeLayout (_root) _root.addView(dragIcon); 它工作正常，添加了 ImageView。

那么为什么不能使用 _view ViewGroup，_view.addView(dragIcon)？

Answer 1

由于您正在使用 ViewGroup，这是一个抽象类，您应该实现抽象方法 onLayout，其中每个子项的每个 layout 方法必须调用 View 组。有关更多信息，请查看 this回答。

我认为您可以使用 FrameLayout，它是 ViewGroup 的子类。它实现了 onLayout 方法，因此您无需再次实现它。

这是 ViewGroup 的工作代码，我在其中明确调用了唯一一个子项 (dragIcon) 的 layout 方法。

ExampleActivity.java

public class ExampleActivity extends AppCompatActivity {

    ViewGroup _view ;
    RelativeLayout _root;
    ImageView dragIcon;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_example);
        _root = (RelativeLayout) findViewById(R.id.exampleLayout);

        _view  = new ViewGroup(ExampleActivity.this) {
            @Override
            protected void onLayout(boolean changed, int l, int t, int r, int b) {
                dragIcon.layout(l, t, r, b); //CHECK THIS
            }
        };

        _view .setBackgroundColor(0xFF00FF00);
        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, 200);
        params.setMargins(10, 0, 10, 0);
        _view .setLayoutParams(params);
        _view .setTranslationX(0);
        _view .setTranslationY(80);
       // selectView(_view);

        _root.addView(_view );

        _view .setTag(R.string.app_name, "" );
        _view .setTag(R.string.app_name, "" + 0);


        dragIcon = new ImageView(ExampleActivity.this);
        dragIcon.setImageResource(R.drawable.heart1);
        RelativeLayout.LayoutParams imgParams = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        imgParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);

        _view .addView(dragIcon); // This Is What I Want, But This Doesn't Work.

        //sample_root.addView(dragIcon); // Don't Want This, But This Works.
    }

}

activity_example.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/exampleLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.anil.raceorganizer.ExampleActivity">
</RelativeLayout>