在 android studio 中添加 textwatcher 后，我的 firebase RecyclerView 沒有顯示任何內容

Question

我想要的實際上是一個搜索文本字段和一個基於搜索文本字段中的文本的回收視圖和顯示適配器。 下面的鏈接是我參考的代碼。 如何使用 TextWatcher 實現 Firebase 回收器？

綁定視圖

@BindView(R.id.searchFood) SearchView mSearchFood;
@BindView(R.id.isharedfood_recyclerview) RecyclerView mISharedFoodRecyclerView;

iFoodSharedActivity.java

       @Override
            protected void onCreate(Bundle savedInstanceState) {
   

             super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_ifoodshared);
                ButterKnife.bind(this);
                setSupportActionBar(mToolbar);
                getSupportActionBar().setTitle("iFoodShared");
                getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_baseline_keyboard_backspace_24);
                getSupportActionBar().setDisplayHomeAsUpEnabled(true);
                getSupportActionBar().setDisplayShowHomeEnabled(true);
                mAuth = FirebaseAuth.getInstance();
                mFirestore = FirebaseFirestore.getInstance();
                itemRef = mFirestore.collection("FoodShare");
                user = mAuth.getCurrentUser().getDisplayName();
                 mSearchFood.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
        @Override
        public boolean onQueryTextSubmit(String s) {
            return false;
        }

        @Override
        public boolean onQueryTextChange(String s) {
            s = mSearchFood.getQuery().toString();
            setUpRecyclerView (s);
            return false;
        }
    });
            }
   


    private void setUpRecyclerView(final String s){
    Query query = itemRef
            .orderBy("timeStamp", Query.Direction.DESCENDING)
            .whereEqualTo("sharerName", user)
            .startAt(s.toUpperCase()).endAt(s + "\uf8ff");
    FirestoreRecyclerOptions<FoodModel> options = new FirestoreRecyclerOptions.Builder<FoodModel>()
            .setQuery(query, FoodModel.class)
            .build();

    iFoodSharedAdapter = new iFoodSharedAdapter(options);

    RecyclerView recyclerView = findViewById(R.id.isharedfood_recyclerview);
    recyclerView.setLayoutManager(new GridLayoutManager(this, 2));
    recyclerView.setAdapter(iFoodSharedAdapter);
}

    @Override
    public void onStart() {
        super.onStart();
        iFoodSharedAdapter.startListening();

    }

    public void onStop() {
        super.onStop();
        iFoodSharedAdapter.stopListening();
    }

錯誤顯示

  E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.fyp.fypfoodbank, PID: 29614
java.lang.NullPointerException: Attempt to invoke virtual method 'void com.fyp.fypfoodbank.Adapters.iFoodSharedAdapter.startListening()' on a null object reference
    at com.fyp.fypfoodbank.Activities.iFoodSharedActivity.onStart(iFoodSharedActivity.java:125)
    at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1392)
    at android.app.Activity.performStart(Activity.java:7260)
    at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3009)
    at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:180)
    at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:165)
    at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:142)
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:70)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1840)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:207)
    at android.app.ActivityThread.main(ActivityThread.java:6878)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:876)

Answer 1

你想一個添加OnQueryTextListener通過你的搜索查看setOnQueryTextListener（） ，這onQueryTextChange被稱為每次輸入字符串變化的時間。