Question

我正在从SurfaceInspectionListActivity向AddSurfaceInspectionActivity发送对象

在putExtra上，我可以在调试模式下查看数据，但是在检索数据时却出现NULL

我试图以String的形式获取它以进行测试，结果也导致NULL

surfaceObjString = getIntent().getStringExtra("myjsonSurfaceObject2");

这是SurfaceInspectionListActivity意图代码

public void addSurfaceInspection(View view) {

        Intent intent = new Intent(SurfaceInspectionListActivity.this, AddSurfaceInspectionActivity.class);
        intent.putExtra("myjsonSurfaceObject2", surfaceObject);
        startActivity(intent);
        finish();
    }

以下是AddSurfaceInspectionActivity上的检索代码

 Gson gson = new Gson();
        surfaceObj = gson.fromJson(getIntent().getStringExtra("myjsonSurfaceObject2"), Surfaces.class);

Answer 1

尝试：

public void addSurfaceInspection(View view) {

    Intent intent = new Intent(SurfaceInspectionListActivity.this, AddSurfaceInspectionActivity.class);
     Gson gson = new Gson();
   String sruface = gson.toJson(surfaceObject, Surfaces.class);
    intent.putExtra("myjsonSurfaceObject2", sruface );
    startActivity(intent);
    finish();
}

Answer 2

首先通过工具Surfaces接口制作Serializable Serializable。然后更改SurfaceInspectionListActivity：

public void addSurfaceInspection(View view) {

    Intent intent = new Intent(SurfaceInspectionListActivity.this, AddSurfaceInspectionActivity.class);

    Bundle bundle = new Bundle();
    bundle.putSerializable("myjsonSurfaceObject2", surfaceObject);

    intent.putExtras(bundle);

    startActivity(intent);
    finish();
}

为了Surface中的AddSurfaceInspectionActivity对象：

Surface surface = getIntent().getSerializableExtra("myjsonSurfaceObject2");

Answer 3

尝试一下：

使用Gson将对象转换为JSON
将其传递给活动

在SurfaceInspectionListActivity中，使用Gson将其转换回对象

public void addSurfaceInspection(View view) {

Intent intent = new Intent(SurfaceInspectionListActivity.this, AddSurfaceInspectionActivity.class);
//Convert to string
Gson gson = new Gson();
String json = gson.toJson(surfaceObject);
intent.putStringExtra("myjsonSurfaceObject2", json);
startActivity(intent);
finish();
}

在AddSurfaceInspectionActivity中：

 Gson gson = new Gson();
 surfaceObj = gson.fromJson(getIntent().getStringExtra("myjsonSurfaceObject2"), Surfaces.class);

Answer 4

如果您已经在使用已实现Serializable的对象，则无需再使用Gson。只需使用putExtra()和getExtra()。像这样：

// there is nothing need to be changed here.
public void addSurfaceInspection(View view) {
    Intent intent = new Intent(SurfaceInspectionListActivity.this, AddSurfaceInspectionActivity.class);
    intent.putExtra("myjsonSurfaceObject2", surfaceObject);
    startActivity(intent);
    finish();
}

然后使用以下方法获取对象：

Bundle bundle = intent.getExtra();
surfaceObj = (Surfaces) bundle.getSerializable("myjsonSurfaceObject2");

如果 Gson 是您的先决条件，则可以使用以下方式：

 // get the String of object
public static String convertToGsonString(Surface surfaceObject) {
  Gson gson = new Gson();
  return gson.toJson(surfaceObject);
}

// convert to object from String
public static Surface convertToObjectFromString(String objString) {
  Type type = new TypeToken<Surface>() {}.getType();

  Gson gson = new Gson();
  return gson.fromJson(objString, type);
}

然后您可以使用上述方法发送意图：

public void addSurfaceInspection(View view) {
    Intent intent = new Intent(SurfaceInspectionListActivity.this, AddSurfaceInspectionActivity.class);
    intent.putExtra("myjsonSurfaceObject2", convertToGsonString(surfaceObject));
    startActivity(intent);
    finish();
}

然后收到它：

 Bundle extra = getIntent().getExtra();
 String objString = extra.getString("myjsonSurfaceObject2");

 surfaceObj = convertToObjectFromString(objString);

请注意，使用Gson时不需要使用Serializable。

gson.fromJson（getIntent（）。getStringExtra（）返回null

4 个答案: