我知道有這樣的問題，但沒有解決我的..我正在嘗試將 'RecyclerView' 設(shè)為 'OnItemClickListener' ，但是當(dāng)我運行該應(yīng)用程序時，它停止了。你能告訴我錯誤在哪里嗎？這是代碼：（請注意錯誤在于使項目可點擊）public class TeacherActivity extends AppCompatActivity {private FirebaseAuth mAuth=FirebaseAuth.getInstance();private FirebaseUser currentUser= mAuth.getCurrentUser();;private FirebaseFirestore db = FirebaseFirestore.getInstance();private String UserId =currentUser.getUid();private static String city;private TeacherAdapter teacherAdapter;public static final String EXTRA_PATH = "com.example.exercise.EXTRA_PATH";@Overrideprotected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_teacher); setUpRecyclerView(); teacherAdapter.setOnItemClickListener(new TeacherAdapter.OnItemClickListener() { @Override public void onItemClick(DocumentSnapshot documentSnapshot, int position) { String path = documentSnapshot.getReference().getPath(); Intent intent = new Intent(TeacherActivity.this, SecondActivity.class); intent.putExtra(EXTRA_PATH, path); startActivity(intent); } });}// end of onCreateprivate void setUpRecyclerView(){ Query query = db.collection("Teachers"); FirestoreRecyclerOptions < Teacher > options = new FirestoreRecyclerOptions.Builder<Teacher>() .setQuery(query, Teacher.class) .build(); teacherAdapter = new TeacherAdapter(options); RecyclerView recyclerView = findViewById(R.id.recycler_view); recyclerView.setHasFixedSize(true); //for performane reasons recyclerView.setLayoutManager(new LinearLayoutManager(this)); recyclerView.setAdapter(teacherAdapter); teacherAdapter.startListening();}@Overrideprotected void onStart() { super.onStart();}@Overrideprotected void onStop() { super.onStop(); teacherAdapter.stopListening();}}// end of class
1 回答
慕萊塢森
TA貢獻1810條經(jīng)驗 獲得超4個贊
您收到以下錯誤：
E/AndroidRuntime：致命異常：主進程：com.example.exercise，PID：29966 java.lang.RuntimeException：無法啟動活動 ComponentInfo{com.example.exercise/com.example.exercise.TeacherActivity}：java.lang。 NullPointerException：嘗試在空對象引用上調(diào)用虛擬方法“void com.example.exercise.TeacherAdapter.setOnItemClickListener(com.example.exercise.TeacherAdapter$OnItemClickListener)”
因為您正在調(diào)用.setOnItemClickListener()當(dāng)時的teacherAdapter對象。null要解決這個問題，您只需移動以下代碼塊：
teacherAdapter.setOnItemClickListener(new TeacherAdapter.OnItemClickListener() {
@Override
public void onItemClick(DocumentSnapshot documentSnapshot, int position) {
String path = documentSnapshot.getReference().getPath();
Intent intent = new Intent(TeacherActivity.this, SecondActivity.class);
intent.putExtra(EXTRA_PATH, path);
startActivity(intent);
}
});
在聲明適配器之后：
teacherAdapter = new TeacherAdapter(options);
按照你的setUpRecyclerView()方法，你的問題就會得到解決。
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