示例代码：
mLinearLayoutManager = new LinearLayoutManager(this);
mLinearLayoutManager.setReverseLayout(true);
mLinearLayoutManager.setStackFromEnd(true);
mMessageRecyclerView.setLayoutManager(mLinearLayoutManager);
我该如何将新项（在我的情况下是消息）添加到 Recycler View 的底部，同时仍保持视图的“重力”在顶部？
目前，以下内容有效：
不起作用的是：
尝试删除这两行或将它们设置为false
layoutManager.setReverseLayout(true);
layoutManager.setStackFromEnd(true);
setStackFromEnd方法将视图设置为显示最后一个元素，布局方向保持不变，而setReverseLayout方法将改变Adapter添加元素的顺序。
尝试使用这些方法在键盘出现时将你的RecyclerView和EditText向上移动。
<activity name="YourActivity"
android:windowSoftInputMode="stateHidden|adjustResize">
//stateHidden -> keyboard is hidden when you first open the activity
//adjustResize -> this will adjust the layout resize option
...
</activity>
在AndroidManifest.xml文件中。
将RecyclerView置于顶部。
<android.support.v7.widget.RecyclerView
android:id="@+id/messageRecyclerViewRep"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="@+id/linearLayout3"
android:layout_marginLeft="36dp"
android:scrollbars="vertical" />
首先将recyclerView放在底部，随着键盘的弹出将其向上推。
<LinearLayout
android:id="@+id/recyclerContainer"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@+id/linearLayout3"
android:layout_above="@+id/linearLayout"
android:gravity="bottom">
<android.support.v7.widget.RecyclerView
android:id="@+id/messageRecyclerViewRep"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="36dp"
android:scrollbars="vertical" />
</LinearLayout>
当键盘弹出时，将recyclerView滚动到底部，即当recyclerView的布局更改时（您可以在编辑文本处处于活动状态、聚焦、单击或类似情况下执行相同的操作。我已在recyclerView的布局更改上完成了此操作。）
recyclerView.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
@Override
public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
if (bottom < oldBottom) {
recyclerView.postDelayed(new Runnable() {
@Override
public void run() {
recyclerView.smoothScrollToPosition(mAdapter.getItemCount());
}
}, 100);
}
}
});
setReverseLayout(true) 会反转项目遍历和布局顺序。第一个项目将出现在末尾而不是视图或内容。
setStackFromEnd(true) 会从视图底部开始填充回收站列表内容。
需要使用 setStackFromEnd(true) 而不是 setReverseLayout(true)
在 XML 中，Recyclerview 的高度应为 match_parent
下面是可工作的代码。
activity xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/btnAdd"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Add" />
<android.support.v7.widget.RecyclerView
android:id="@+id/rcList"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipToPadding="true" />
</LinearLayout>
列表项xml布局
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_marginRight="20dp"
android:gravity="center_vertical">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content" android:textSize="23sp"
android:layout_height="wrap_content" android:textColor="#4a4883"
android:text="Test Text" />
</FrameLayout>
Adapter class
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {
private static final String TAG = "CustomAdapter";
private ArrayList<String> mDataSet;
private int size = 0;
public static class ViewHolder extends RecyclerView.ViewHolder {
private final TextView textView;
public ViewHolder(View v) {
super(v);
v.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d(TAG, "Element " + getAdapterPosition() + " clicked.");
}
});
textView = (TextView) v.findViewById(R.id.textView);
}
public TextView getTextView() {
return textView;
}
}
public CustomAdapter(ArrayList<String> dataSet) {
mDataSet = dataSet;
if (mDataSet != null && !mDataSet.isEmpty()) {
size = mDataSet.size();
}
}
public void refreshData(String add) {
if (!TextUtils.isEmpty(add)) {
mDataSet.add(add);
size = mDataSet.size();
notifyDataSetChanged();
}
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
// Create a new view.
View v = LayoutInflater.from(viewGroup.getContext())
.inflate(R.layout.list_item, viewGroup, false);
return new ViewHolder(v);
}
@Override
public void onBindViewHolder(ViewHolder viewHolder, final int position) {
Log.d(TAG, "Element " + position + " set.");
viewHolder.getTextView().setText(mDataSet.get(position));
}
@Override
public int getItemCount() {
return size;
}
}
Activity class
public class MainActivity extends AppCompatActivity {
private RecyclerView mRecyclerView;
protected CustomAdapter mAdapter;
protected LinearLayoutManager mLayoutManager;
protected ArrayList<String> listString = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = (RecyclerView) findViewById(R.id.rcList);
mLayoutManager = new LinearLayoutManager(this);
mLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
/**
*setStackFromEnd true will fill the content(list item) from the bottom of the view
*/
mLayoutManager.setStackFromEnd(true);
mLayoutManager.setReverseLayout(true);
mRecyclerView.setLayoutManager(mLayoutManager);
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
findViewById(R.id.btnAdd).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int temp = mAdapter.getItemCount() + 1;
mAdapter.refreshData("Test text " + temp);
mRecyclerView.smoothScrollToPosition(mAdapter.getItemCount());
}
});
mAdapter = new CustomAdapter(listString);
mRecyclerView.setAdapter(mAdapter);
}
}
@Override
public void onBindViewHolder(ViewHolder viewHolder, final int position) {
Log.d(TAG, "Element " + position + " set.");
viewHolder.getTextView().setText(mDataSet.get(getItemCount() - 1 -position));
}
这样做的效果是，由于你从上往下加载项目，所以最后插入的项目会显示在底部。不需要对任何XML或其他代码进行任何更改。
我曾经遇到过Recylerview在键盘弹出时没有自适应大小的问题，因此我采用了这种方法。
祝一切顺利！
setStackFromEnd=true 和 setReverseLayout=true。
Recycler View Holder
public class TestingFirebaseHolder extends RecyclerView.ViewHolder {
private TextView mTextView;
private TextView mTextView2;
public TestingFirebaseHolder(View itemView) {
super(itemView);
mTextView = itemView.findViewById(R.id.textViewTesting);
mTextView2 = itemView.findViewById(R.id.textViewTesting2);
}
public void setTextView(String text,String text2)
{
mTextView.setText(text);
mTextView2.setText(text2);
}
}
测试类
public class TestingUser {
public String UserName;
public String mUid;
public TestingUser() {
}
public TestingUser(String userName, String uid) {
UserName = userName;
mUid = uid;
}
}
private EditText mEditText;
private RecyclerView mRecyclerView;
private FirebaseRecyclerAdapter<TestingUser,TestingFirebaseHolder> mAdapter;
private FirebaseUser mUser;
private DatabaseReference mReference;
mEditText = findViewById(R.id.testingEditText);
mRecyclerView = findViewById(R.id.hello_rec);
mUser = FirebaseAuth.getInstance().getCurrentUser();
mReference = FirebaseDatabase.getInstance().getReference();
LinearLayoutManager ll = new LinearLayoutManager(this);
ll.setReverseLayout(true); // set this
ll.setStackFromEnd(true); // set this
mRecyclerView.setLayoutManager(ll);
Query query = mReference.child("Testing").child(mUser.getUid()).orderByValue();
mAdapter = new FirebaseRecyclerAdapter<TestingUser, TestingFirebaseHolder>(
TestingUser.class,R.layout.testing_recycler_layout,TestingFirebaseHolder.class,query
) {
@Override
protected void populateViewHolder(TestingFirebaseHolder viewHolder, TestingUser model, int position) {
viewHolder.setTextView(model.mUid,model.UserName);
}
};
mRecyclerView.setAdapter(mAdapter);
public void buttonClick(View view) {
if(!mEditText.getText().toString().isEmpty())
{
TestingUser user = new TestingUser("Salman",mEditText.getText().toString());
mReference.child("Testing").child(mUser.getUid()).push().setValue(user);
mEditText.setText("");
}
}
mLinearLayoutManager = new LinearLayoutManager(this);
mLinearLayoutManager.stackFromEnd(true)
mLinearLayoutManager.isSmoothScrollbarEnabled(true)
mMessageRecyclerView.setLayoutManager(mLinearLayoutManager);
FirebaseRecyclerAdapter<FriendlyMessage, MessageViewHolder> mFirebaseAdapter;。 - user8618899