通过可点击的 ListView 将 firebase 数据从一个活动传递到另一个活动

Question

在尝试将 firebase 数据从列表视图传递到单独的活动时，我最初将数据放入列表时遇到了以下错误。

非常感谢您对此问题的任何帮助。

当我将列表从类型字符串更改为类型 ReportInformation 时出现问题，这是在两个活动之间传递信息所必需的。在 listView 中选择一个项目，引用的数据应该传递到另一个活动（progressReports.activity）

我的 list_view.java

public class list_view extends AppCompatActivity {

private ArrayAdapter<ReportInformation> arrayAdapter;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_list_view);

    final String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
    DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
    final DatabaseReference uidRef = rootRef.child("ProgressReports").child(uid);
    final List<ReportInformation> list = new ArrayList<>();
    final ArrayList<String> id = new ArrayList<>();
    final Context context = this;
    EditText searchBarProgress = findViewById(R.id.searchBarProgress);
    arrayAdapter = new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_list_item_1, list);

    String key = uidRef.push().getKey();
    ReportInformation report = new ReportInformation();
    report.setTitle("title");
    report.setContent("content");
    report.setKey(key);
    uidRef.child(key).setValue(report);


    ValueEventListener eventListener = new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for (DataSnapshot ds : dataSnapshot.getChildren()) {
                id.add(ds.getKey());
                String title = ds.child("title").getValue(String.class);
                String content = ds.child("content").getValue(String.class);
                String timestamp = ds.child("timestamp").getValue(String.class);
                list.add(title + "\n" + timestamp + "\n" + content);
                Log.d("TAG", title);
            }
            ListView listView = findViewById(R.id.progressList);
            listView.setAdapter(arrayAdapter);

        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    };
    uidRef.addListenerForSingleValueEvent(eventListener);

    final ListView progressList = findViewById(R.id.progressList);

    progressList.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view, int i, long l) {
            ValueEventListener eventListener = new ValueEventListener() {
                @Override
                public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                    ArrayList<ReportInformation> list = new ArrayList<>();
                    for (DataSnapshot ds : dataSnapshot.getChildren()) {
                        ReportInformation report = ds.getValue(ReportInformation.class);
                        list.add(report);
                    }
                   // Intent intent = new Intent(list_view.this, ProgressReports.class);
                    ListView listView = findViewById(R.id.progressList);
                    listView.setAdapter(arrayAdapter);
                   // startActivity(intent);
                    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                        @Override
                        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                            ReportInformation reportInformation = arrayAdapter.getItem(i);
                            Intent intent = new Intent(list_view.this, ProgressReports.class);
                            intent.putExtra("object", reportInformation);
                            startActivity(intent);
                        }
                    });
                }


                @Override
                public void onCancelled(@NonNull DatabaseError databaseError) {

                }
            };
            uidRef.addListenerForSingleValueEvent(eventListener);
        }
    });

    progressList.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> adapterView, View view, final int j, long l) {
            final DatabaseReference delete = FirebaseDatabase.getInstance().getReference("ProgressReports/" + uid + "/" + id.get(j));
            final AlertDialog.Builder builder = new AlertDialog.Builder(context);
            builder.setMessage("Are you sure you want to delete?");
            builder.setCancelable(true);
            builder.setPositiveButton(
                    "yes",
                    new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            delete.removeValue();
                            Toast.makeText(list_view.this, "Report deleted", Toast.LENGTH_SHORT).show();
                            list.remove(j);
                            arrayAdapter.notifyDataSetChanged();
                        }
                    });
            builder.setNegativeButton("No", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    dialogInterface.cancel();
                }
            });
            builder.show();
            return true;
        }
    });


    searchBarProgress.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

        }

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            (list_view.this).arrayAdapter.getFilter().filter(charSequence);

        }

        @Override
        public void afterTextChanged(Editable editable) {

        }
    });
}

}

Answer 1

在声明列表时，您正在向列表传递一个字符串而不是 ReportInformation 对象。为了解决这个问题，您应该将数据作为该类的对象。所以请更改以下代码行：

String title = ds.child("title").getValue(String.class);
String content = ds.child("content").getValue(String.class);
String timestamp = ds.child("timestamp").getValue(String.class);
list.add(title + "\n" + timestamp + "\n" + content);

到

ReportInformation reportInformation = ds.getValue(ReportInformation.class);
list.add(reportInformation);