传递值Java类

Question

我遇到来自firebase数据库的值和一个简单的textview显示它们的问题。

public class FindReportActivity extends Activity implements View.OnClickListener{

    EditText editTextFindReport;
    TextView textViewCommento;
    TextView textViewGravita;
    ImageView imageViewFindReport;
    String cdt;
    Report report;
    ReportDAO reportDAO = new ReportDAO();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_find_report);
        imageViewFindReport = (ImageView) findViewById(R.id.imageViewFindReport);
        editTextFindReport = (EditText) findViewById(R.id.editTextCDT);
        textViewCommento= (TextView) findViewById(R.id.textViewcommento);
        textViewGravita= (TextView) findViewById(R.id.textViewgravita);

        imageViewFindReport.setOnClickListener(this);

    }
    @Override
    public void onClick(View v) {
        if( v == imageViewFindReport){

            cdt = editTextFindReport.getText().toString().trim();
            textViewCommento.setText(reportDAO.findReport(cdt));

        }
    }
}

这里是ReportDAO类

public class ReportDAO {
    private FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance();
    private DatabaseReference databaseReference = firebaseDatabase.getReference();
    String commento = "non";

    public ReportDAO(){ }


    public String findReport(String cdt){

        DatabaseReference refReport = databaseReference.child("Report").child(cdt).child("commento");
        refReport.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                commento = dataSnapshot.getValue(String.class);
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });


        return commento;
    }

当我点击imageview时，第一次是空白，第二次是正确值...为什么？

Answer 1

您需要实现一个等待评论可用的侦听器，因为findReport方法是异步的。