如何以编程方式将自定义 Java 视图 class 加载到 RelativeLayout

Question

我想在 RelativeLayout 中加载一些自定义视图，但不知道如何加载。我试过的代码不起作用，因此有人知道如何正确执行此操作吗？

XML

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        android:paddingBottom="@dimen/activity_vertical_margin">

        <TextView
            android:id="@+id/textView0"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:layout_marginBottom="20dp"
            style="@android:style/TextAppearance.Medium" />

        <TextView
            android:id="@+id/textView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:layout_marginBottom="2dp"
            style="@android:style/TextAppearance.Medium"
            android:layout_below="@id/textView0" />
        <View
            android:id="@+id/drawing0"
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:layout_below="@id/textView1" />
        <View
            android:id="@+id/drawing1"                
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:layout_marginTop="2dp"
            android:layout_below="@id/drawing0" />
        <TextView
            android:id="@+id/textView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@android:style/TextAppearance.Large"
            android:layout_below="@id/drawing1" />
        <TextView
            android:id="@+id/textView3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@android:style/TextAppearance.Large"
            android:layout_marginStart="10dp"
            android:layout_below="@id/drawing1"
            android:layout_toEndOf="@id/textView2" />
        <TextView
            android:id="@+id/textView4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@android:style/TextAppearance.Medium"
            android:layout_below="@id/textView3" />
        <TextView
            android:id="@+id/textView5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@android:style/TextAppearance.Medium"
            android:layout_marginBottom="30dp"
            android:layout_below="@id/textView4" />
    </RelativeLayout>

</ScrollView>

Shapes.java

public class Shapes extends android.support.v4.app.Fragment {

    public Shapes() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

        return inflater.inflate(R.layout.shapes, container, false);
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        View v = getView();
        assert v != null;

        //blue shape drawing
        View cv0 = (View)v.findViewById(R.id.drawing0);
        v.addView(new BlueShape(getActivity()));

        //green shape drawing
        View cv1 = (View)v.findViewById(R.id.drawing1);
        v.addView(new GreenShape(getActivity()));

        super.onActivityCreated(savedInstanceState);
    }
}

BlueShape.java

public class BlueShape extends View {
    private final Paint mBlue = new Paint();

    ...

}

GreenShape.java

public class GreenShape extends View {
    private final Paint mGreen = new Paint();

    ...

}

Answer 1

cv0、cv1 不是 ViewGroup。尝试将cv0、cv1改为ViewGroup，并将onActivityCreated的代码移至onViewCreated回调方法。

这里是参考网站。 android/view/ViewGroup

Answer 2

我认为问题在于您使用的是 v.addView() 而不是

cv0.addView()

但我建议使用以下内容代替您的 View:

 <LinearLayout
            android:id="@+id/drawing1"                
            android:layout_width="match_parent"
            android:layout_height="40dp"
            android:layout_marginTop="2dp"
            android:layout_below="@id/drawing0" />

然后，在 Java 代码中：

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    LinearLayout cv0 = (LinearLayout)getView().findViewById(R.id.drawing0);
    cv0.addView(new BlueShape(getActivity()), 0, new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT));

Answer 3

参考https://developer.android.com/guide/topics/ui/custom-components.html

具体在

Modifying an Existing View Type

Use the Custom Component

您可以在 RelativeLayout

中更改 xml

<View...

到

<your.package.GreenShape...

如果你事先不知道视图是什么，那就把它改成

<FrameLayout... instead of <View...

然后以编程方式将子项（GreenShape 或 BlueShape）添加到该框架布局

如何以编程方式将自定义 Java 视图 class 加载到 RelativeLayout

How to load a Custom Java View class to a RelativeLayout programmatically

java

xml

android

android-relativelayout

android-paint