你需要添加下一行…

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

所有这些答案都让我接近了答案，但它们都遗漏了一个关键细节。经过一番研究，我发现最简单的方法是将以下3个步骤结合起来:

使用支持库的DividerItemDecoration 用正确的颜色创建分隔线 在主题中设置这个分隔符为listDivider

步骤1:在配置RecyclerView时

recyclerView.addItemDecoration(
        new DividerItemDecoration(context, layoutManager.getOrientation()));

第二步:在res/drawable/divider_gray.xml这样的文件中

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <size android:width="1px" android:height="1px" />
    <solid android:color="@color/gray" />
</shape>

步骤3:在应用程序的主题

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Other theme items above -->
    <item name="android:listDivider">@drawable/divider_gray</item>
</style>

编辑:更新跳过最后的分隔符: 在使用了一些之后，我意识到它在最后一项之后画了一个分隔符，这很烦人。所以我修改了第1步，如下所示，以覆盖在DividerItemDecoration的默认行为(当然，制作一个单独的类是另一种选择):

recyclerView.addItemDecoration(
        new DividerItemDecoration(context, layoutManager.getOrientation()) {
            @Override
            public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
                int position = parent.getChildAdapterPosition(view);
                // hide the divider for the last child
                if (position == parent.getAdapter().getItemCount() - 1) {
                    outRect.setEmpty();
                } else {
                    super.getItemOffsets(outRect, view, parent, state);
                }
            }
        }
);

为了让nj的回答更简单一点，你可以这样做:

public class DividerColorItemDecoration extends DividerItemDecoration {

    public DividerColorItemDecoration(Context context, int orientation) {
        super(context, orientation);
        setDrawable(ContextCompat.getDrawable(context, R.drawable.line_divider));
    }
}

正确的方法是为RecyclerView定义ItemDecoration如下所示

SimpleDividerItemDecoration.java

public class SimpleDividerItemDecoration extends RecyclerView.ItemDecoration {
    private Drawable mDivider;
 
    public SimpleDividerItemDecoration(Context context) {
        mDivider = ContextCompat.getDrawable(context, R.drawable.line_divider);
    }
 
    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();
 
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View child = parent.getChildAt(i);
 
            RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
 
            int top = child.getBottom() + params.bottomMargin;
            int bottom = top + mDivider.getIntrinsicHeight();
 
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }
}

或者如果您正在使用kotlin: SimpleDividerItemDecoration.kt

class SimpleDividerItemDecoration(context: Context, @DrawableRes dividerRes: Int) : ItemDecoration() {

    private val mDivider: Drawable = ContextCompat.getDrawable(context, dividerRes)!!

    override fun onDrawOver(c: Canvas, parent: RecyclerView) {
        val left = parent.paddingLeft
        val right = parent.width - parent.paddingRight
        val childCount = parent.childCount
        for (i in 0 until childCount) {
            val child: View = parent.getChildAt(i)
            val params = child.layoutParams as RecyclerView.LayoutParams
            val top: Int = child.bottom + params.bottomMargin
            val bottom = top + mDivider.intrinsicHeight
            mDivider.setBounds(left, top, right, bottom)
            mDivider.draw(c)
        }
    }
}
    

line_divider.xml:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
 
    <size
        android:width="1dp"
        android:height="1dp" />
 
    <solid android:color="@color/dark_gray" />
 
</shape>

最后像这样设置

recyclerView.addItemDecoration(new SimpleDividerItemDecoration(this));

Edit

正如@Alan Solitar指出的那样

context.getResources().getDrawable(R.drawable.line_divider); 

是折旧而不是你可以使用的

ContextCompat.getDrawable(context,R.drawable.line_divider);

不幸的是，Android只是把小事情变得太复杂了。实现你想要的最简单的方法，没有实现这里的DividerItemDecoration:

为RecyclerView添加你想要的分割线颜色的背景色:

<RecyclerView
    android:id="@+id/rvList"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:divider="@color/colorLightGray"
    android:scrollbars="vertical"
    tools:listitem="@layout/list_item"
    android:background="@android:color/darker_gray"/>

添加底部边距(android:layout_marginBottom)到项目的布局根(list_item.xml):

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginBottom="1dp">

    <TextView
        android:id="@+id/tvName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="John Doe" />

    <TextView
        android:id="@+id/tvDescription"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tvName"
        android:text="Some description blah blah" />

</RelativeLayout>

这将在项目和RecyclerView的背景色之间提供1dp的空间(它是深灰色，将作为分隔符出现)。

我认为这是最简单的方法

mDividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(),
                DividerItemDecoration.VERTICAL);
// or DividerItemDecoration.HORIZONTALL
        mDividerItemDecoration.setDrawable(getDrawable(R.drawable.myshape));
        recyclerView.addItemDecoration(mDividerItemDecoration);

注意:myshape可以是你想要做分隔的高度的矩形