RecyclerView适配器中的NullPointerException
编辑:建议的重复问题不以任何方式回答我的问题,形状或形式。RecyclerView适配器中的NullPointerException
我在设置我的RecyclerView适配器时遇到了问题。我得到两个错误:
09-19 20:01:38.601 22710-22710/com.yitter.android E/RecyclerView: No adapter attached; skipping layout
...和:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setAdapter(android.support.v7.widget.RecyclerView$Adapter)' on a null object reference
at com.yitter.feed.FeedActivity.lambda$retrieveYeets$68(FeedActivity.java:402)
at com.yitter.feed.FeedActivity.access$lambda$3(FeedActivity.java:0)
at com.yitter.feed.FeedActivity$$Lambda$4.done(Unknown Source)
at com.parse.ParseTaskUtils$2$1.run(ParseTaskUtils.java:116)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
FeedActivity:
在我initialise()
类(内onCreate()
),我建立了我的RecyclerView和适配器:
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setHasFixedSize(true);
adapter = new FeedAdapter(FeedActivity.this, retrieveYeets());
recyclerView.setAdapter(adapter);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
我通过一个List基于查询:
public List<ParseObject> retrieveYeets() {
String groupId = ParseUser.getCurrentUser().getString("groupId");
ParseQuery<ParseObject> query = new ParseQuery<>(ParseConstants.CLASS_YEET);
query.whereContains(ParseConstants.KEY_GROUP_ID, groupId);
query.orderByDescending("lastReplyUpdatedAt");
query.setLimit(1000);
query.findInBackground((yeets, e) -> {
if (mSwipeRefreshLayout.isRefreshing()) {
mSwipeRefreshLayout.setRefreshing(false);
}
if (e == null) {
// We found messages!
mYeets = yeets;
String[] usernames;
usernames = new String[mYeets.size()];
int i = 0;
for(ParseObject yeet : mYeets) {
usernames[i] = yeet.getString(ParseConstants.KEY_SENDER_NAME);
i++;
}
// Add data to FeedAdapter
FeedAdapter adapter = new FeedAdapter(
FeedActivity.this,
mYeets);
recyclerView.setAdapter(adapter);
}
});
return mYeets;
}
全码:https://gist.github.com/santafebound/e71bc433ddf03a791ac1d89679559490
FeedAdapter:
我有一种感觉问题出在我的适配器,但我无法弄清楚。可能会出现什么问题?
全码:https://gist.github.com/santafebound/c8207bd9075f1025243e5b6661b7afc5
答:
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setHasFixedSize(true);
adapter = new FeedAdapter(FeedActivity.this, retrieveYeets());
recyclerView.setAdapter(adapter);
,并在我的retrieveYeets()
方法,去掉下面几行:
我在MainActivity改变了这一点:
想必您在您的xml布局文件中引用了您的RecyclerView块中的文件,该文件不存在于您的绘图或其他文件夹或文件中...检查该行之前的错误行,并且可以看到行中的错误#... 然后检查...
我不认为有缺少的布局文件。 – santafebound
那是什么?我发布了主要活动和适配器。我错过了什么吗? – santafebound
一些事情是这样的:
你的错误是显而易见的。第一个原因,因为你没有附加正确的适配器,第二个说你正试图在初始化recyclerView之前设置加热器 –
哈哈,你的男孩感觉咸吗? – santafebound