Android RecyclerView 滚动到中间位置的方法示例

// 滚动到指定位置
recyclerView.scrollToPosition(position);
// 平滑滚动到指定位置
recyclerView.smoothScrollToPosition(position);

// scrollBy(x, y)这个方法是自己去控制移动的距离，单位是像素,所以在使用scrollBy(x, y)需要自己去计算移动的高度或宽度。
recyclerView.scrollBy(x, y)

mRecyclerView.scrollToPosition(0);
mRecyclerView.scrollBy(0,400);

mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
      @Override
      public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
        super.onScrollStateChanged(recyclerView, newState);
      }

      @Override
      public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);
      }
    });

 Rect rect = new Rect();
 mRecyclerView.getGlobalVisibleRect(rect);
 reHeight = rect.bottom - rect.top - vHeight;
当运行 scrollToPosition 后，点击条目就会出现在视野当中，这时候，计算出相应的位移即可。需要注意一点的是，当点击条目在视野内的时候，是不会运行 scrollToPosition 方法的。

    int top = mRecyclerView.getChildAt(position - firstPosition).getTop();
int half = reHeight / 2;
    mRecyclerView.scrollBy(0, top - half);

public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
private RecyclerView mRecyclerView;
private LinearLayoutManager mLayoutManager;
private RecyclerView.Adapter mAdapter;
private String[] data;
private Handler handler;
private boolean isClick = false;
private static int vHeight = -1;
private static int reHeight = -1;
private static int position = 0;
private static final int target = 10;
private static boolean isMove = false;
private Runnable runnable;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
handler = new Handler();
mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
//创建默认的线性LayoutManager
mLayoutManager = new LinearLayoutManager(this);
mLayoutManager.setAutoMeasureEnabled(true);
mRecyclerView.setLayoutManager(mLayoutManager);
//如果可以确定每个item的高度是固定的，设置这个选项可以提高性能
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setNestedScrollingEnabled(false);
data = new String[]{"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21"};
runnable = new Runnable() {
@Override
public void run() {
if (isVisible()) {
scrollToMiddle();
} else {
mRecyclerView.scrollToPosition(position);
isMove = true;
isClick = false;
}
}
};
mAdapter = new MyAdapter(data, new MyAdapter.onRecyclerViewItemClick() {
@Override
public void onItemClick(View v, int pos) {
Toast.makeText(MainActivity.this, "第" + pos + "行", Toast.LENGTH_SHORT).show();
position = pos;
vHeight = v.getHeight();
Rect rect = new Rect();
mRecyclerView.getGlobalVisibleRect(rect);
reHeight = rect.bottom - rect.top - vHeight;
// handler.removeCallbacksAndMessages(null);
handler.removeCallbacks(runnable);
handler.postDelayed(runnable, 4000);
isClick = true;
}
});
mRecyclerView.setAdapter(mAdapter);
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
Log.d(TAG, "" + newState);
if (newState == RecyclerView.SCROLL_STATE_DRAGGING && !isMove) {
handler.removeCallbacks(runnable);
}
if (newState == RecyclerView.SCROLL_STATE_IDLE) {
if (isClick) {
handler.postDelayed(runnable, 4000);
}
}
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
if (isMove) {
if (vHeight < 0) {
isMove = false;
return;
}
scrollToMiddle();
}
}
});
public void scrollToMiddle() {
final int firstPosition = mLayoutManager.findFirstVisibleItemPosition();
int top = mRecyclerView.getChildAt(position - firstPosition).getTop();
Log.d(TAG, " position" + position + " " + top);
int half = reHeight / 2;
mRecyclerView.scrollBy(0, top - half);
isMove = false;
}
public boolean isVisible() {
final int firstPosition = mLayoutManager.findFirstVisibleItemPosition();
final int lastPosition = mLayoutManager.findLastVisibleItemPosition();
return position <= lastPosition && position  = firstPosition;
}
@Override
protected void onDestroy() {
super.onDestroy();
handler.removeCallbacksAndMessages(null);
handler = null;
}
}