Question

我创建了两个海关视图：一个来自SwipeRefreshLayout（名称：ColorSwipeRefreshLayout），另一个来自RecyclerView（名称：ColorRecyclerView）。

我只想在ColorSwipeRefreshLayout中包含ColorRecyclerView，最后在我的片段中包含ColorSwipeRefreshLayout。但是每当我想在我的Fragment类中调用我的ColorRecyclerView时，对象上得到一个NullPointerException并且不明白为什么......

有代码：

ColorRecyclerView.java

public class ColorRecyclerView extends RecyclerView {
final static int COLUMN_COUNT = 3;
RecyclerView.LayoutManager layoutManager;
RVColorAdapter adapter;
List<HueColor> colors;
ApiHelper apiHelper;

public ColorRecyclerView(Context context) {
    super(context);
    initializeView(context);
}

public ColorRecyclerView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initializeView(context);
}

public ColorRecyclerView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    initializeView(context);
}

public void setHelper(ApiHelper apiHelper) {
    this.apiHelper = apiHelper;
}

public void update(List<HueColor> colors) {
    this.colors = colors;
    adapter = new RVColorAdapter(apiHelper,colors);
    setAdapter(adapter);
}

private void initializeView(Context context) {
    layoutManager = new GridLayoutManager(context,COLUMN_COUNT);
    setLayoutManager(layoutManager);
}

colorrecyclerview.xml

<android.support.v7.widget.RecyclerView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

ColorSwipeRefreshLayout.java

public class ColorSwipeRefreshLayout extends SwipeRefreshLayout {
ColorRecyclerView colorRecyclerView;

public ColorSwipeRefreshLayout(Context context) {
    super(context);
    initializeView(context);
}

public ColorSwipeRefreshLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
    initializeView(context);
}

private void initializeView(Context context) {
    LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View v = inflater.inflate(R.layout.swiperefreshlayout_color, this, true);
    colorRecyclerView = (ColorRecyclerView) v.findViewById(R.id.colorRecyclerView);

    setColorSchemeResources(R.color.color_scheme_1_1, R.color.color_scheme_1_2,
            R.color.color_scheme_1_3, R.color.color_scheme_1_4);

}

public ColorRecyclerView getColorRecyclerView() {
    return this.colorRecyclerView;
}

colorswiperefreshlayout.xml

<android.support.v4.widget.SwipeRefreshLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <com.color.hue.ui.view.ColorRecyclerView
        android:id="@+id/colorRecyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

ColorFragment.java

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    // ...code...
    View view = inflater.inflate(R.layout.fragment_color, container, false);
    ButterKnife.bind(this, view);

    mRecyclerView = mSwipeRefreshLayout.getColorRecyclerView();
    mRecyclerView.setHelper(mApiHelper); // Got NullPointerEx here

    // ...code...
    return view;
}

colorfragment.xml

<com.color.hue.ui.view.ColorSwipeRefreshLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/colorSwipeRefreshLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

谢谢：）

编辑：我在ColorSwipeRefreshLayout的initializeView中添加了通胀，它可以工作：）

Answer 1

您的SwipeRefreshLayout不应在其构造函数中调用initializeView。

由于您在片段中从布局中对其进行了充气，因此在调用构造函数时尚未添加任何视图。所以

colorRecyclerView = (ColorRecyclerView) findViewById(R.id.colorRecyclerView);`

找不到任何回收者视图。

一个选项是在initializeView方法中充气/创建recyclerview，或者稍后查找参考资料。

您的初始化的一个好处可能是onFinishInflate。

如何在Android的自定义视图中创建自定义视图？

1 个答案: