Bundle.getString() 返回空值？

Question

我正在尝试通过捆绑包中的字符串传递 json。该字符串被很好地加载到包中。但看起来它收到了错误的包。

在一个class的onCreate中：

    if(intent!=null){

        jsonString = intent.getStringExtra(this.getBaseContext().getResources().getString(R.string.recipe_detail_json));

        //prints the string just fine here
        System.out.println(jsonString);

        Bundle bundle = new Bundle();
        bundle.putString("RECIPE_DETAIL_JSON",jsonString);
        srdFragment= new SelectRecipeDetailFragment();
        srdFragment.setArguments(bundle);
        getSupportFragmentManager().beginTransaction()
                .replace(R.id.recipe_list_step_container, srdFragment).commit();

    }

    setContentView(R.layout.select_a_recipe_step);

在我的片段中：

 private String jsonString;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Bundle bundle = getArguments();
    jsonString = bundle.getString("RECIPE_DETAIL_JSON");

    //this string prints null
    System.out.println(jsonString);

}

Answer 1

您必须像这样在片段内部创建实例

public class SelectRecipeDetailFragment extends Fragment{

   public static SelectRecipeDetailFragment newInstance(String jsonString) {
         SelectRecipeDetailFragment frag = new SelectRecipeDetailFragment();
          Bundle args = new Bundle();
          args.putString("RECIPE_DETAIL_JSON", jsonString);
          frag.setArguments(args);
          return frag;
   }


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Bundle bundle = getArguments();
        jsonString = bundle.getString("RECIPE_DETAIL_JSON");

        //this string prints null
        System.out.println(jsonString);

    }
}

然后在你的 activity

中像这样使用

 getSupportFragmentManager().beginTransaction()
            .replace(R.id.recipe_list_step_container, SelectRecipeDetailFragment.newInstance(jsonString).commit();

Answer 2

在片段中使用这个

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
  Bundle savedInstanceState) {
jsonString = getArguments().getString("RECIPE_DETAIL_JSON");
return inflater.inflate(R.layout.fragment, container, false);
}

Bundle.getString() 返回空值？

Bundle.getString() returning null?

android

android-fragments

android-bundle