无法反序列化对象。无法将类型java.util.Date的值转换为String

时间：2018-11-09 17:18:23

标签： java android firebase runtime-error google-cloud-firestore

我是Android世界中的一个新手。我正在尝试从Firebase Cloud Firestore实时读取数据。我已经上传了Tree.java类4的对象，其属性为时间戳，如在Firebase控制台屏幕截图和Tree.java类代码中所见。

firebase console - Cloudfirestore

Tree.java 

import com.google.firebase.Timestamp;

import java.util.HashMap;
import java.util.Map;

import static com.example.malayishant.greencare.AddTree.DOP;
import static com.example.malayishant.greencare.AddTree.ID;
import static com.example.malayishant.greencare.AddTree.MANURE;
import static com.example.malayishant.greencare.AddTree.WATER;
import static com.example.malayishant.greencare.AddTree.WEED;

public class Tree {

    private String id;
    private Timestamp dop;
    //private GeoPoint geo;
    private Timestamp water;
    private Timestamp weed;
    private Timestamp manure;

    public Tree() {
    }

    public Tree(String id, Timestamp dop, Timestamp water,
                Timestamp weed, Timestamp manure) {
        this.id = id;
        this.dop = dop;

        this.water = water;
        this.weed = weed;
        this.manure = manure;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public Timestamp getDop() {
        return dop;
    }

    public void setDop(Timestamp dop) {
        this.dop = dop;
    }

    public Timestamp getWater() {
        return water;
    }

    public void setWater(Timestamp water) {
        this.water = water;
    }

    public Timestamp getWeed() {
        return weed;
    }

    public void setWeed(String name) {
        this.weed = weed;
    }

    public Timestamp getManure() {
        return manure;
    }

    public void setManure(Timestamp manure) {
        this.manure = manure;
    }

}

以下代码用于将数据上传到Cloud Fire存储。

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.Timestamp;
import com.google.firebase.firestore.DocumentReference;
import com.google.firebase.firestore.FirebaseFirestore;

import java.util.HashMap;
import java.util.Map;

public class AddTree extends AppCompatActivity {
public static final String ID = "id";
public static final String DOP = "dop";

public static final String WATER = "water";
public static final String WEED = "weed";
public static final String MANURE = "manure";

// Access a Cloud Firestore instance from your Activity

FirebaseFirestore db = FirebaseFirestore.getInstance();
private Button mButton;

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

    mButton = findViewById(R.id.buttonAdd);
    mButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            // your handler code here
            uploadTree();
        }
    });

}

public void uploadTree() {
    EditText IdEditText = findViewById(R.id.IdeditText);
    String id = IdEditText.getText().toString();
    // Timestamp dop = Timestamp.now();
    //geo
    if (id.isEmpty()) {
        return;
    }
    Map<String, Object> tree = new HashMap<String, Object>();
    tree.put(ID, id);
    tree.put(DOP, Timestamp.now());
    tree.put(WATER, Timestamp.now());
    tree.put(WEED, Timestamp.now());
    tree.put(MANURE, Timestamp.now());
    db.collection("trees")
            .add(tree)
            .addOnSuccessListener(new OnSuccessListener<DocumentReference>() {
                @Override
                public void onSuccess(DocumentReference documentReference) {
                    // Log.d(TAG, "DocumentSnapshot added with ID: " + documentReference.getId());
                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                     Log.w(TAG, "Error adding document", e);
                }
            });


}

}

我正在使用以下代码从Cloud Firestore获取数据。代码片段中标记的代码片段中出现的runtume错误。我越来越 当我运行代码时，出现“ java.lang.RuntimeException：无法反序列化对象。无法将java.util.Date类型的值转换为String（在字段'weed'中找到）”。

firestoreDB.collection("trees")
                .get()
                .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                    @Override
                    public void onComplete(@NonNull Task<QuerySnapshot> task) {
                        if (task.isSuccessful()) {
                           List<Tree> treeList = new ArrayList<>();


                            for (DocumentSnapshot doc : task.getResult()) {
                                Tree tree = doc.toObject(Tree.class);/*this line causing the error*/

                                treeList.add(tree);
                            }

                            mAdapter = new TreeDbAdapter(treeList, getContext(), firestoreDB);
                            RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getContext());
                            recyclerView.setLayoutManager(mLayoutManager);
                            recyclerView.setItemAnimator(new DefaultItemAnimator());
                            recyclerView.setAdapter(mAdapter);
                        } else {
                            Log.d(TAG, "Error getting documents: ", task.getException());

                        }
                    }
                });

我遇到的错误

11-09 20:58:46.182 10665-10665/com.example.malayishant.greencare E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.malayishant.greencare, PID: 10665
    java.lang.RuntimeException: Could not deserialize object. Failed to convert value of type java.util.Date to String (found in field 'weed')
        at com.google.firebase.firestore.util.CustomClassMapper.deserializeError(com.google.firebase:firebase-firestore@@17.1.2:524)
        at com.google.firebase.firestore.util.CustomClassMapper.convertString(com.google.firebase:firebase-firestore@@17.1.2:445)
        at com.google.firebase.firestore.util.CustomClassMapper.deserializeToClass(com.google.firebase:firebase-firestore@@17.1.2:217)
        at com.google.firebase.firestore.util.CustomClassMapper.deserializeToType(com.google.firebase:firebase-firestore@@17.1.2:180)
        at com.google.firebase.firestore.util.CustomClassMapper.access$200(com.google.firebase:firebase-firestore@@17.1.2:53)
        at com.google.firebase.firestore.util.CustomClassMapper$BeanMapper.deserialize(com.google.firebase:firebase-firestore@@17.1.2:700)
        at com.google.firebase.firestore.util.CustomClassMapper$BeanMapper.deserialize(com.google.firebase:firebase-firestore@@17.1.2:674)
        at com.google.firebase.firestore.util.CustomClassMapper.convertBean(com.google.firebase:firebase-firestore@@17.1.2:503)
        at com.google.firebase.firestore.util.CustomClassMapper.deserializeToClass(com.google.firebase:firebase-firestore@@17.1.2:242)
        at com.google.firebase.firestore.util.CustomClassMapper.convertToCustomClass(com.google.firebase:firebase-firestore@@17.1.2:97)
        at com.google.firebase.firestore.DocumentSnapshot.toObject(com.google.firebase:firebase-firestore@@17.1.2:203)
        at com.google.firebase.firestore.QueryDocumentSnapshot.toObject(com.google.firebase:firebase-firestore@@17.1.2:121)
        at com.google.firebase.firestore.DocumentSnapshot.toObject(com.google.firebase:firebase-firestore@@17.1.2:183)
        at com.google.firebase.firestore.QueryDocumentSnapshot.toObject(com.google.firebase:firebase-firestore@@17.1.2:101)
        at com.example.malayishant.greencare.FragmentDb$1.onEvent(FragmentDb.java:64)
        at com.example.malayishant.greencare.FragmentDb$1.onEvent(FragmentDb.java:52)
        at com.google.firebase.firestore.Query.lambda$addSnapshotListenerInternal$2(com.google.firebase:firebase-firestore@@17.1.2:882)
        at com.google.firebase.firestore.Query$$Lambda$3.onEvent(com.google.firebase:firebase-firestore@@17.1.2)
        at com.google.firebase.firestore.util.ExecutorEventListener.lambda$onEvent$0(com.google.firebase:firebase-firestore@@17.1.2:42)
        at com.google.firebase.firestore.util.ExecutorEventListener$$Lambda$1.run(com.google.firebase:firebase-firestore@@17.1.2)
        at android.os.Handler.handleCallback(Handler.java:742)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:157)
        at android.app.ActivityThread.main(ActivityThread.java:5602)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:774)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:652)

1 个答案:

答案 0 :(得分：1)

您遇到以下错误：

  

java.lang.RuntimeException：无法反序列化对象。无法将类型java.util.Date的值转换为String（在字段“ weed”中找到）

因为在您的Tree类中，您的setWeed()方法的参数的类型为String，而不是 Timestamp。

要解决此问题，请更改以下代码行：

public void setWeed(String name) {
    this.weed = weed;
}

到

public void setWeed(Timestamp weed) {
    this.weed = weed;
}
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