Recyclerview Dividers不会出现

Question

分频器

我有一个`RecyclerView＆＃39;我试图添加分隔符。

mRecyclerView.addItemDecoration(new DividerItemDecoration(
mRecyclerView.getContext(), DividerItemDecoration.HORIZONTAL));

但是当我加载应用程序时，我没有分隔符。 我错过了什么？

代码

这是整个活动：

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;
    private String[] myDataset;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
        myDataset = new String[]{"Cool", "Dope", "Awesome"};

        // 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);

        // use a linear layout manager
        mLayoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(mLayoutManager);
        mRecyclerView.addItemDecoration(new DividerItemDecoration(mRecyclerView.getContext(), DividerItemDecoration.HORIZONTAL));



        // specify an adapter (see also next example)
        mAdapter = new MyAdapter(myDataset, "Item");
        mRecyclerView.setAdapter(mAdapter);
    }

}

适配器

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
private String[] mDataset;
private String mCategory;

// Provide a reference to the views for each data item
// Complex data items may need more than one view per item, and
// you provide access to all the views for a data item in a view holder
public static class ViewHolder extends RecyclerView.ViewHolder {
    // each data item is just a string in this case
    TextView itemName;
    TextView itemCategory;
    ViewHolder(View v) {
        super(v);
        itemName = (TextView) v.findViewById(R.id.itemName);
        itemCategory = (TextView) v.findViewById(R.id.itemCategory);
    }
}

// Provide a suitable constructor (depends on the kind of dataset)
public MyAdapter(String[] dataset, String category) {
    mDataset = dataset;
    mCategory = category;
}

// Create new views (invoked by the layout manager)
@Override
public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
                                               int viewType) {
    // create a new view
    View v = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.sweep_text_view_layout, parent, false);
    // set the view's size, margins, paddings and layout parameters

    ViewHolder vh = new ViewHolder(v);
    return vh;
}

// Replace the contents of a view (invoked by the layout manager)
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    // - get element from your dataset at this position
    // - replace the contents of the view with that element
    holder.itemName.setText(mDataset[position]);
    holder.itemCategory.setText(mCategory);

}

// Return the size of your dataset (invoked by the layout manager)
@Override
public int getItemCount() {
    return mDataset.length;
}
}`

Answer 1

试试这个自定义代码：

 @SuppressWarnings("ALL")
 public class DividerItemDecorator extends RecyclerView.ItemDecoration 
 {

private static final int[] ATTRS = new int[]{
        android.R.attr.listDivider
};

private static final int HORIZONTAL_LIST = 
LinearLayoutManager.HORIZONTAL;

public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

private final Drawable mDivider;

private int mOrientation;

public DividerItemDecorator(Context context, 
@SuppressWarnings("SameParameterValue") int orientation) {
    final TypedArray a = context.obtainStyledAttributes(ATTRS);
    mDivider = a.getDrawable(0);
    a.recycle();
    setOrientation(orientation);
}

private void setOrientation(int orientation) {
    if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
        throw new IllegalArgumentException("invalid orientation");
    }
    mOrientation = orientation;
}

@Override
public void onDraw(Canvas c, RecyclerView parent) {
    if (mOrientation == VERTICAL_LIST) {
        drawVertical(c, parent);
    } else {
        drawHorizontal(c, parent);
    }
}

private void drawVertical(Canvas c, RecyclerView parent) {
    final int left = parent.getPaddingLeft();
    final int right = parent.getWidth() - parent.getPaddingRight();

    final int childCount = parent.getChildCount();
    for (int i = 0; i < childCount; i++) {
        final View child = parent.getChildAt(i);
        final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                .getLayoutParams();
        final int top = child.getBottom() + params.bottomMargin;
        final int bottom = top + mDivider.getIntrinsicHeight();
        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(c);
    }
}

private void drawHorizontal(Canvas c, RecyclerView parent) {
    final int top = parent.getPaddingTop();
    final int bottom = parent.getHeight() - parent.getPaddingBottom();

    final int childCount = parent.getChildCount();
    for (int i = 0; i < childCount; i++) {
        final View child = parent.getChildAt(i);
        final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                .getLayoutParams();
        final int left = child.getRight() + params.rightMargin;
        final int right = left + mDivider.getIntrinsicHeight();
        mDivider.setBounds(left, top, right, bottom);
        mDivider.draw(c);
    }
}

@Override
public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
    if (mOrientation == VERTICAL_LIST) {
        outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
    } else {
        outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
    }
  }
}

然后应用这样的装饰：

    LinearLayoutManager layoutManager = new LinearLayoutManager(this);
    mRecyclerView.setLayoutManager(layoutManager);
    mRecyclerView.setHasFixedSize(true);

    mRecyclerView.addItemDecoration(new DividerItemDecorator(this, 
    DividerItemDecorator.VERTICAL_LIST));