Java 带意图传递时，可包裹自定义对象将丢失实例值

我遇到了一个让我完全无法相信的问题。我的自定义对象似乎在通过意图发送到新活动后丢失了值。为什么一个对象只有在通过意图传递后才会丢失其实例变量的值

我有实现Parcelable的自定义对象，用于存储特定数据

public class Vehicle implements Parcelable, Serializable{
private static final String TAG = "vehicleObject";
public String vehicleType;
public String refID;
public String title;

public HashMap<String, String> reservedSpecs;
public HashMap<String, String> generalSpecs;
public HashMap<String, String> engineSpecs;
public HashMap<String, String> powerTrainSpecs;
public HashMap<String, String> otherSpecs;

public Vehicle(String vehicleType, String year, String make, String model){
    this.refID = UUID.randomUUID().toString();
    this.title = year + " " + make + " " + model;
    this.vehicleType = vehicleType;
    this.reservedSpecs = new HashMap<>();
    this.reservedSpecs.put("year", year);
    this.reservedSpecs.put("make", make);
    this.reservedSpecs.put("model", model);
}

public Vehicle(Parcel source){
    Bundle bundle = source.readBundle(getClass().getClassLoader());
    vehicleType = bundle.getString("vehicleType");
    refID = bundle.getString("refID");
    title = bundle.getString("title");

    reservedSpecs = (HashMap) bundle.getSerializable("reserved");
    generalSpecs = (HashMap) bundle.getSerializable("general");
    engineSpecs = (HashMap) bundle.getSerializable("engine");
    powerTrainSpecs = (HashMap) bundle.getSerializable("power");
    otherSpecs = (HashMap) bundle.getSerializable("other");
}

@Override
public void writeToParcel(Parcel dest, int flags){
    Bundle bundle = new Bundle();
    bundle.putString("vehicleType", vehicleType);
    bundle.putString("refID", refID);
    bundle.putString("title", title);
    bundle.putSerializable("reserved", reservedSpecs);
    bundle.putSerializable("general", generalSpecs);
    bundle.putSerializable("engine", engineSpecs);
    bundle.putSerializable("power", powerTrainSpecs);
    bundle.putSerializable("other", otherSpecs);

    dest.writeBundle(bundle);
}

@Override
public int describeContents(){
    return 0;
}

/**
  *Generic getters/Setters for all instance variables 
**/

/**
 * Creator required for class implementing the parcelable interface.
 */
public static final Parcelable.Creator<Vehicle> CREATOR = new Creator<Vehicle>() {

    @Override
    public Vehicle createFromParcel(Parcel source) {
        return new Vehicle(source);
    }

    @Override
    public Vehicle[] newArray(int size) {
        return new Vehicle[size];
    }
};

运行此命令后，再次调用对象

    01-09 20:28:13.382 2359-2359/com.kd8bny.maintenanceman A/getGeneralSpecs: get{} //Empty hashmap that had G=G
01-09 20:28:13.382 2359-2359/com.kd8bny.maintenanceman A/getEngineSpecs: get{}  //Empty hashmap that had E=E
01-09 20:28:13.383 2359-2359/com.kd8bny.maintenanceman A/getPowerTrainSpecs: get{}  //Empty hashmap that had P=P
01-09 20:28:13.383 2359-2359/com.kd8bny.maintenanceman A/getOtherSpecs: get{Po=Oo}   //hashmap that retains its value
01-09 20:28:13.383 2359-2359/com.kd8bny.maintenanceman E/adptr_inf: [{Po=Oo}] //And what the adapter sees as it calls on the object again
01-09 20:28:13.383 2359-2359/com.kd8bny.maintenanceman E/adptr_inf: [{Po=Oo}]

为什么这些价值正在消失？我可以用不同的方法来解决这个问题吗。我尝试过使用Singleton和PassingSerializable，得到了相同的结果。

---

提前谢谢

我终于找到了这个问题的症结所在

JAVA是按值传递的

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每当我创建一个新对象时，我的自定义对象就会传递hashmap的值。然后我将编辑对象或调用它，hashmap将返回它的最后一个键/值对。我通过使用Gson序列化hashmap并稍后返回其形式来解决此问题。

我看不出问题，但您可以尝试切换到Parceler，看看是否解决了此问题。有趣的项目。我要试一试，所以我把问题缩小了一点。事实证明，recycler视图的行为很奇怪，因为我将setAdapter放在了onStart方法中。但是，将对象发送到其他活动时，问题仍然存在。结果表明，parcelable工作正常，但在onResume方法运行后，我的对象实例发生了更改。我丢失了数据。

public class test extends AppCompatActivity {
private ArrayList<Vehicle> roster;
private Vehicle vehicle;
RecyclerView cardList;
RecyclerView.LayoutManager cardMan;
RecyclerView.Adapter cardListAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_test);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);


    Bundle bundle = getIntent().getBundleExtra("bundle");
    vehicle = bundle.getParcelable("vehicle");
    int vehiclePos = bundle.getInt("pos", -1);

    //Set recycler view
    cardList = (RecyclerView) findViewById(R.id.info_cardList);
    cardMan = new LinearLayoutManager(this);
    cardList.setLayoutManager(cardMan);

    }

@Override
public void onResume(){
    super.onResume();

    cardListAdapter = new adapter_info(vehicle);
    cardList.setAdapter(cardListAdapter);
 }

public adapter_info(Vehicle vehicle) {
    ArrayList<HashMap> temp = new ArrayList<>();
    temp.add(vehicle.getGeneralSpecs());
    temp.add(vehicle.getEngineSpecs());
    temp.add(vehicle.getPowerTrainSpecs());
    temp.add(vehicle.getOtherSpecs());       
}
/**
*Adapter stuff such as onCreateViewHodler and bind
**/

 01-09 20:27:19.850 2359-2359/com.kd8bny.maintenanceman D/TEST!!!: create{G=G}{E=E}{P=P}{Po=Oo}   //All 4 hashmaps with values
01-09 20:27:19.850 2359-2359/com.kd8bny.maintenanceman A/getGeneralSpecs: get{G=G} //A log of each hashmap in the object's getter method
01-09 20:27:19.850 2359-2359/com.kd8bny.maintenanceman A/getEngineSpecs: get{E=E}
01-09 20:27:19.851 2359-2359/com.kd8bny.maintenanceman A/getPowerTrainSpecs: get{P=P}
01-09 20:27:19.851 2359-2359/com.kd8bny.maintenanceman A/getOtherSpecs: get{Po=Oo}
01-09 20:27:19.851 2359-2359/com.kd8bny.maintenanceman E/adptr_inf: [{G=G}, {E=E}, {P=P}, {Po=Oo}] //Finally what the adapter sees using the getter method
01-09 20:27:19.851 2359-2359/com.kd8bny.maintenanceman E/adptr_inf: [{G=G}, {E=E}, {P=P}, {Po=Oo}]

    01-09 20:28:13.382 2359-2359/com.kd8bny.maintenanceman A/getGeneralSpecs: get{} //Empty hashmap that had G=G
01-09 20:28:13.382 2359-2359/com.kd8bny.maintenanceman A/getEngineSpecs: get{}  //Empty hashmap that had E=E
01-09 20:28:13.383 2359-2359/com.kd8bny.maintenanceman A/getPowerTrainSpecs: get{}  //Empty hashmap that had P=P
01-09 20:28:13.383 2359-2359/com.kd8bny.maintenanceman A/getOtherSpecs: get{Po=Oo}   //hashmap that retains its value
01-09 20:28:13.383 2359-2359/com.kd8bny.maintenanceman E/adptr_inf: [{Po=Oo}] //And what the adapter sees as it calls on the object again
01-09 20:28:13.383 2359-2359/com.kd8bny.maintenanceman E/adptr_inf: [{Po=Oo}]