Question

我正在开发材料设计应用。我想在RecyclerView中使用HelpActivity显示一个列表。

问题是我收到了以下错误：第java.lang.RuntimeException: java.lang.IllegalStateException: RecyclerView has no LayoutManager行(HelpActivity.java:28)。

此处的HelpActivity.java文件代码：

public class HelpActivity extends AppCompatActivity {

    public RecyclerView mRecyclerView;
    public RecyclerView.LayoutManager mLayoutManager;
    public RecyclerView.Adapter mAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_help);

        mRecyclerView = (RecyclerView) findViewById(R.id.helpActivityContent);

        // use a linear layout manager
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        mRecyclerView.setLayoutManager(layoutManager);

        // use this setting to improve performance if you know that changes
        // in content do not change the layout size of the RecyclerView
        mRecyclerView.setHasFixedSize(true);

        mAdapter = new HelpContentAdapter(helpContents);
        mRecyclerView.setAdapter(mAdapter);

        initializeData();

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        toolbar.setTitleTextColor(Color.parseColor("#2196F3"));
        setSupportActionBar(toolbar);

        /*final Drawable upArrow = ContextCompat.getDrawable(this, R.drawable.abc_ic_ab_back_mtrl_am_alpha);
        upArrow.setColorFilter(getResources().getColor(R.color.colorAccent), PorterDuff.Mode.SRC_ATOP);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setHomeAsUpIndicator(upArrow);*/

        /*FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });*/
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

    class HelpActivityContent {
        String option;
        String subOption;
        int icon;

        HelpActivityContent(String option, String subOption, int icon) {
            this.option = option;
            this.subOption = subOption;
            this.icon = icon;
        }
    }

    public List<HelpActivityContent> helpContents;

    // This method creates an ArrayList that has three Person objects
// Checkout the project associated with this tutorial on Github if
// you want to use the same images.
    private void initializeData(){
        helpContents = new ArrayList<>();
        helpContents.add(new HelpActivityContent("123", "", R.drawable.ic_action_a));
        helpContents.add(new HelpActivityContent("123", "", R.drawable.ic_action_b));
        helpContents.add(new HelpActivityContent("321", "111", R.drawable.ic_action_c));
        helpContents.add(new HelpActivityContent("1", "2", R.drawable.ic_action_d));
    }

    public class HelpContentAdapter extends RecyclerView.Adapter<HelpContentAdapter.HelpContentViewHolder>{

        public class HelpContentViewHolder extends RecyclerView.ViewHolder {
            TextView option;
            TextView subOption;
            ImageView icon;

            HelpContentViewHolder(View itemView) {
                super(itemView);
                option = (TextView)itemView.findViewById(R.id.option);
                subOption = (TextView)itemView.findViewById(R.id.subOption);
                icon = (ImageView)itemView.findViewById(R.id.optionIcon);
            }

        }

        List<HelpActivityContent> helpContents;

        HelpContentAdapter(List<HelpActivityContent> helpContents){
            this.helpContents = helpContents;
        }

        @Override
        public int getItemCount() {
            return helpContents.size();
        }

        @Override
        public HelpContentViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
            View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.content_help, viewGroup, false);
            HelpContentViewHolder pvh = new HelpContentViewHolder(v);
            return pvh;
        }

        @Override
        public void onBindViewHolder(HelpContentViewHolder helpContentViewHolder, int i) {
            helpContentViewHolder.option.setText(helpContents.get(i).option);
            helpContentViewHolder.subOption.setText(helpContents.get(i).subOption);
            helpContentViewHolder.icon.setImageResource(helpContents.get(i).icon);
        }

        @Override
        public void onAttachedToRecyclerView(RecyclerView recyclerView) {
            super.onAttachedToRecyclerView(recyclerView);
        }

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        int id = item.getItemId();

        switch (id) {
            case android.R.id.home:
                supportFinishAfterTransition();
                return true;
        }

        return super.onOptionsItemSelected(item);

    }

}

此处的content_help.xml文件代码：

<?xml version="1.0" encoding="utf-8"?>

<!-- A RecyclerView with some commonly used attributes -->
<android.support.v7.widget.RecyclerView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/helpActivityContent"
    android:scrollbars="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/activity_help"
    tools:context="com.abc.xyz.HelpActivity">

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/optionIcon"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginRight="16dp"
        />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/option"
        android:layout_toRightOf="@+id/optionIcon"
        android:layout_alignParentTop="true"
        android:textSize="30sp"
        />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/subOption"
        android:layout_toRightOf="@+id/optionIcon"
        android:layout_below="@+id/option"
        />

</RelativeLayout>
</android.support.v7.widget.RecyclerView>

我无法弄清问题是什么。

请告诉我。

提前致谢。

Answer 1

您不能将您的子元素直接放在回收者视图中您需要创建单独的行布局，就像您在listview中创建的那样。

只需删除在recycleler视图中编写的xml代码，然后将其插入row_layout xml文件中，然后在适配器内膨胀该行布局文件。

<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/activity_help"
tools:context="com.abc.xyz.HelpActivity">

<ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/optionIcon"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_marginRight="16dp"
    />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/option"
    android:layout_toRightOf="@+id/optionIcon"
    android:layout_alignParentTop="true"
    android:textSize="30sp"
    />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/subOption"
    android:layout_toRightOf="@+id/optionIcon"
    android:layout_below="@+id/option"
    />

</RelativeLayout>

只需为包含上述内容的row_layout创建单独的文件，然后在 oncreateviewholder 中对其进行充气：

View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.**<new_layout_you_will_create>**, viewGroup, false);

Answer 2

我只是对你的content_help.xml进行了一些小改动，它对我来说很好用.. content_help.xml

如果您在activity_help.xml中使用recyclelerview，则不需要对行内容使用相同的内容。

希望这能解决您的问题

为什么我收到错误：java.lang.RuntimeException：java.lang.IllegalStateException：RecyclerView没有LayoutManager（HelpActivity.java:28）

2 个答案: