android - 自定义抽屉导航 ArrayIndefOutOfBounds

Question

我实现了抽屉导航适配器，我想看起来像这样:

1. 标题
2. 列表项
3. 列表项
4. TextView

但是我有错误，我不知道为什么要使用一个“如果”。当我删除行布局并且仅删除 header.xml 和 drawer_list_item.xml 时，它起作用了。我刚刚开始学习，你能帮帮我吗？

java.lang.ArrayIndexOutOfBoundsException: length=0; index=0
        at com.example.test.adapters.NavDrawerAdapter.onBindViewHolder(NavDrawerAdapter.java:182)
        at com.example.test.adapters.NavDrawerAdapter.onBindViewHolder(NavDrawerAdapter.java:31)
        at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:4138)
        at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:3448)
        at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:3340)
        at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1810)
        at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1306)
        at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1269)
        at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:523)
        at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:1988)
        at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:2237)
        at android.view.View.layout(View.java:15684)
        at android.view.ViewGroup.layout(ViewGroup.java:4981)
        at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:931)
        at android.view.View.layout(View.java:15684)
        at android.view.ViewGroup.layout(ViewGroup.java:4981)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
        at android.view.View.layout(View.java:15684)
        at android.view.ViewGroup.layout(ViewGroup.java:4981)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
        at android.view.View.layout(View.java:15684)
        at android.view.ViewGroup.layout(ViewGroup.java:4981)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
        at android.view.View.layout(View.java:15684)
        at android.view.ViewGroup.layout(ViewGroup.java:4981)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
        at android.view.View.layout(View.java:15684)
        at android.view.ViewGroup.layout(ViewGroup.java:4981)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
        at android.view.View.layout(View.java:15684)
        at android.view.ViewGroup.layout(ViewGroup.java:4981)
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2186)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1920)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1106)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6018)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:792)
        at android.view.Choreographer.doCallbacks(Choreographer.java:596)
        at android.view.Choreographer.doFrame(Choreographer.java:557)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:778)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:155)
        at android.app.ActivityThread.main(ActivityThread.java:5696)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1028)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)

这是我的适配器

public class NavDrawerAdapter extends RecyclerView.Adapter<NavDrawerAdapter.ViewHolder> {

    private static final int TYPE_HEADER = 0;
    private static final int TYPE_ITEM = 1;
    private static final int TYPE_LINE = 2;


    private String mNavTitles[];
    private Integer mNavTitlesId[];

    private String name;
    private String email;
    Context context;

    public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
        int Holderid;

        TextView textView;
        ImageView mHashImageView;
        ImageView profile;
        TextView Name;
        TextView email;
        Context mContext;
        String mTitles[];
        Integer mTitlesId[];
        TextView mLine;

        public ViewHolder(View itemView,int ViewType, Context context) {                 // Creating ViewHolder Constructor with View and viewType As a parameter
            super(itemView);
            mContext = context;
            itemView.setClickable(true);
            itemView.setOnClickListener(this);


            if(ViewType == TYPE_ITEM) {
                textView = (TextView) itemView.findViewById(R.id.hashTextView)
                mHashImageView = (ImageView) itemView.findViewById(R.id.hashImageView);
                Holderid = 1;
            } else if(ViewType == TYPE_HEADER) {
                Name = (TextView) itemView.findViewById(R.id.name);
                email = (TextView) itemView.findViewById(R.id.email);
                profile = (ImageView) itemView.findViewById(R.id.circleView);
                Holderid = 0;
            } else if(ViewType == TYPE_LINE){
                mLine = (TextView) itemView.findViewById(R.id.lineTextView);
                Holderid = 2;
            }
        }

        @Override
        public void onClick(View v) {
            Toast.makeText(mContext, "The Item Clicked is: " + getPosition(), Toast.LENGTH_SHORT).show();
        }
    }

    public NavDrawerAdapter(String Name, String Email, Context context, String[] mTitles, int[] mTitlesId){
        name = Name;
        email = Email;
        this.context = context;

        mNavTitles = mTitles;
        mNavTitlesId = mTitlesId;
    }

    @Override
    public NavDrawerAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        if (viewType == TYPE_ITEM) {
            View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.drawer_list_item,parent,false);

            ViewHolder vhItem = new ViewHolder(v,viewType,context);

            return vhItem;

        } else if (viewType == TYPE_HEADER) {

            View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.header,parent,false);

            ViewHolder vhHeader = new ViewHolder(v,viewType,context);

            return vhHeader;


        } else if(viewType == TYPE_LINE) {
            View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.line,parent,false);

            ViewHolder vhLine = new ViewHolder(v,viewType,context);

            return vhLine;
        }
        return null;

    }

    @Override
    public void onBindViewHolder(NavDrawerAdapter.ViewHolder holder, int position) {
        if(holder.Holderid == 1) {
            holder.textView.setText(mNavTitles[position - 1]);
        }
        else if(holder.Holderid == 0){
            holder.Name.setText(name);
            holder.email.setText(email);
        } else {
            holder.mLine.setText("Text");
        }
    }

    @Override
    public int getItemCount() {
        return mNavTitles.length+2; // the number of items in the list will be +1 the titles including the header view.
    }

    @Override
    public int getItemViewType(int position) {
        if (position == 0)
            return TYPE_HEADER;
        else if (position == 1)
            return TYPE_ITEM;
        return TYPE_LINE;
    }

}

我在 MainActivity 中使用它:

mRecyclerView = (RecyclerView) findViewById(R.id.RecyclerView); // Assigning the RecyclerView Object to the xml View
mRecyclerView.setHasFixedSize(true);                            // Letting the system know that the list objects are of fixed size

mAdapter = new NavDrawerAdapter(NAME, EMAIL, PROFILE, this.getApplicationContext());
mRecyclerView.setAdapter(mAdapter);                              // Setting the adapter to RecyclerView
mLayoutManager = new LinearLayoutManager(this);                 // Creating a layout Manager
mRecyclerView.setLayoutManager(mLayoutManager);                 // Setting the layout Manager

mDrawerLayout = (DrawerLayout) findViewById(R.id.DrawerLayout);        // mDrawerLayout object Assigned to the view
mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, mToolbar, R.string.open_drawer, R.string.close_drawer) {

    @Override
    public void onDrawerOpened(View drawerView) {
        super.onDrawerOpened(drawerView);
    }

    @Override
    public void onDrawerClosed(View drawerView) {
        super.onDrawerClosed(drawerView);
    }

}; // mDrawerLayout Toggle Object Made
mDrawerLayout.setDrawerListener(mDrawerToggle); // mDrawerLayout Listener set to the mDrawerLayout toggle
mDrawerToggle.syncState();      

这是header.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="178dp"
    android:background="@drawable/background_night_sky"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="56dp"
        android:orientation="vertical"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true">

        <TextView
            android:id="@+id/name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="16dp"
            android:textColor="#ffffff"
            android:text="Name Surname"
            android:textSize="14sp"
            android:textStyle="bold"

            />

        <TextView
            android:id="@+id/email"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="#ffffff"
            android:layout_marginLeft="16dp"
            android:layout_marginTop="5dp"
            android:text="name.surname@gmail.com"
            android:textSize="14sp"
            android:textStyle="normal"

            />
    </LinearLayout>

    <de.hdodenhof.circleimageview.CircleImageView
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:src="@drawable/avatar_small"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="38dp"
        android:id="@+id/circleView"
        />
</RelativeLayout>

这是 line.xml

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

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceSmall"
        android:text="Small Text"
        android:id="@+id/lineTextView"
        android:layout_gravity="center_horizontal"
        android:background="@color/colorPrimary"/>
</LinearLayout>

这是 drawer_list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingTop="4dp"
    android:paddingBottom="4dp"
    android:orientation="horizontal"
    android:clickable="true"
    android:background="?attr/selectableItemBackground">

    <ImageView
        android:layout_width="@dimen/hash_size_y"
        android:layout_height="@dimen/hash_size_x"
        android:scaleType="fitCenter"
        android:layout_marginStart="8dp"
        android:layout_alignParentStart="true"
        android:id="@+id/hashImageView"
        android:src="@drawable/ic_hash_orange_small"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:paddingLeft="8dp"
        android:layout_centerVertical="true"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="HashTag"
        android:id="@+id/hashTextView"
        android:textColor="@color/drawer_background"
        android:textStyle="bold|italic"
        android:layout_toEndOf="@id/hashImageView"/>

</RelativeLayout>

Answer 1

@Override
public void onBindViewHolder(NavDrawerAdapter.ViewHolder holder, int position) {
    if(holder.Holderid == 1) {
        holder.textView.setText(mNavTitles[position - 1]);
    }
    else if(holder.Holderid == 0){
        holder.Name.setText(name);
        holder.email.setText(email);
    } else {
        holder.mLine.setText("Text");
    }
}

@Override
public int getItemCount() {
    return mNavTitles.length+2; // the number of items in the list will be +1 the titles including the header view.
}

问题出在上面几行。您正在返回 mNavTitles.length+2。当数组为空时，您将返回 2，这意味着将使用位置 0 和 1 调用 onBindViewHolde。使用位置 1，您将访问包含任何内容的数组因此导致 ArrayIndexOutBoundException。您可能想要返回 mNavTitles.length+1