无法从 android 应用程序的方法或其他活动中获取数据

Question

我正在尝试将登录应用程序的用户的数据存储在 class 中，以便我可以在所有活动中使用它的所有数据。

我遵循了几个关于可序列化的指南，但我无法让它工作。

此函数从我的 api:

调用用户对象

public void GetGame(String UID){
    String url = "https://worldapi.azurewebsites.net/api/homeracer/user/"+UID;
    final JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, url, null,

            new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    Log.d("tag", "jsonresponse" + response.toString());
                    try {
                        //String name = response.getString("userName");
                        currentUser.setUserId(response.getInt("userId"));
                        currentUser.setStartLat(response.getInt("startLat"));
                        currentUser.setStartLong(response.getDouble("startLong"));
                        currentUser.setEndLat(response.getDouble("endLat"));
                        currentUser.setEndLong(response.getDouble("endLong"));
                        currentUser.setUsername(response.getString("userName"));

                        startLong.setText(String.valueOf(currentUser.getStartLong()));
                        userName.setText(currentUser.getUsername());

                        //Intent sendObj = new Intent(Homescreen.this, Homescreen.class);
                        bundle = new Bundle();
                        bundle.putSerializable("userInfo", currentUser);
                        //sendObj.putExtras(bundle);
                        //startActivity(sendObj);

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.d("error", error.toString());
                }
            }
    );
    jsonObjectRequest.setRetryPolicy(new DefaultRetryPolicy(
            10000,
            DefaultRetryPolicy.DEFAULT_MAX_RETRIES,
            DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));

    //mRequestQueue.add(jsonObjectRequest);
    Volley.newRequestQueue(this).add(jsonObjectRequest);
}

现在，当我在 'onResponse' 方法之外的任何地方尝试从当前用户获取用户名或任何其他数据时。该字段为空。

所以我的问题是：如何设置 currentUser 对象，以便我可以在我的活动中使用它的所有字段并将其发送到其他活动。我试过 sharedpreferences 并且它有效，但我读到的地方并不理想。

用户数据class:

public class UserData implements Serializable {
  int UserId;
  double EndLat, EndLong, StartLat, StartLong;
  String Username;
  /*public Userdata(){

     }

  public Userdata(String username, double endLat, double endLong, double startLat
                             ,double startLong, int userId){
             this.Username = username;
             this.UserId = userId;
             this.StartLat = startLat;
             this.StartLong = startLong;
             this.EndLat = endLat;
             this.EndLong = endLong;

     }*/

  public void setUserId(int _userId) {
    this.UserId = _userId;
  }

  public int getUserId() {
    return UserId;
  }

  public void setEndLat(double _endLat) {
    this.EndLat = _endLat;
  }

  public double getEndLat() {
    return EndLat;
  }

  public void setStartLat(double _startLat) {
    this.StartLat = _startLat;
  }

  public double getStartLat() {
    return StartLat;
  }

  public void setEndLong(double _endLong) {
    this.EndLong = _endLong;
  }

  public double getEndLong() {
    return EndLong;
  }

  public void setStartLong(double _startLong) {
    this.StartLong = _startLong;
  }

  public double getStartLong() {
    return StartLong;
  }

  public void setUsername(String username) {
    this.Username = username;
  }

  public String getUsername() {
    return Username;
  }
}

Answer 1

在 Android 中，您可以通过实现 Parcelable 接口轻松地在整个 Activity 中传递对象。

步骤是：

您的 class 应该实现 Parcelable 接口。
创建一个 Intent 以您想要导航的 Activity 为目标，并使用 putExtra() 方法传递您的对象。
从新 Activity 中检索您的对象。

下面是您的 UserData class 实施 Parcelable。 Android Studio 可帮助您轻松完成此任务。

public class UserData implements Parcelable {
    private int UserId;
    private double EndLat, EndLong, StartLat, StartLong;
    private String Username;

    public void setUserId(int _userId) {
        this.UserId = _userId;
    }

    public int getUserId() {
        return UserId;
    }

    public void setEndLat(double _endLat) {
        this.EndLat = _endLat;
    }

    public double getEndLat() {
        return EndLat;
    }

    public void setStartLat(double _startLat) {
        this.StartLat = _startLat;
    }

    public double getStartLat() {
        return StartLat;
    }

    public void setEndLong(double _endLong) {
        this.EndLong = _endLong;
    }

    public double getEndLong() {
        return EndLong;
    }

    public void setStartLong(double _startLong) {
        this.StartLong = _startLong;
    }

    public double getStartLong() {
        return StartLong;
    }

    public void setUsername(String username) {
        this.Username = username;
    }

    public String getUsername() {
        return Username;
    }

    // Parcelable implementation bellow this line

    protected UserData(Parcel in) {
        UserId = in.readInt();
        EndLat = in.readDouble();
        EndLong = in.readDouble();
        StartLat = in.readDouble();
        StartLong = in.readDouble();
        Username = in.readString();
    }

    public static final Creator<UserData> CREATOR = new Creator<UserData>() {
        @Override
        public UserData createFromParcel(Parcel in) {
            return new UserData(in);
        }

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

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

    @Override
    public void writeToParcel(Parcel parcel, int i) {
        parcel.writeInt(UserId);
        parcel.writeDouble(EndLat);
        parcel.writeDouble(EndLong);
        parcel.writeDouble(StartLat);
        parcel.writeDouble(StartLong);
        parcel.writeString(Username);
    }
}

创建 Intent:

Intent intent = new Intent(context/*your activity*/, TargetActivity.class);

现在将对象传递给意图。 intent.putExtra("your_key",yourObject); 开始你的 activity startActivity(intent).

最后从TargetActivity获取从Intent传递到这里的对象。

UserData yourObject = getIntent().getParcelableExtra("your_key");

就是这样！

无法从 android 应用程序的方法或其他活动中获取数据

Can't get data out of method or in other activities on android app

java

android

android-volley