不相容的类型：列表<FollowUser>无法转换为ArrayList <String>

问题描述：

我试图将List<>从活动传递到片段。不相容的类型：列表<FollowUser>无法转换为ArrayList <String>

点击imageView时， onClick事件触发对服务器的调用，该服务器接受单击imageView的用户的userId和要查看的用户配置文件的userId。我有一个接口，该接口将从服务器获取响应，然后发送到一个新的片段类。我遇到的问题是我无法通过该软件包通过List<>。

这是片段类的newInstance和参数我试图跨越

public static HomeUserProfileFragment newInstance(String postTotal, String followersTotal 
     , String followingTotal, List<UploadPost> uploadPostList, List<FollowUser> followersList, List<FollowUser> followingList) { 

    HomeUserProfileFragment fragment = new HomeUserProfileFragment(); 
    Bundle args = new Bundle(); 
    args.putString(POST_TOTAL, postTotal); 
    args.putString(FOLLOWERS_TOTAL, followersTotal); 
    args.putString(FOLLOWING_TOTAL, followingTotal); 
    args.putStringArrayList(UPLOAD_POST_LIST,uploadPostList); 
    args.putStringArrayList(FOLLOWERS_LIST,followersList); 
    args.putStringArrayList(FOLLOWING_LIST, followingList); 
    fragment.setArguments(args); 
    return fragment; 
}

派虽然这是Activity类，上述片段是从调用。

@Override 
public void onClickUserProfile(String post, String followers, String following, List<UploadPost> uploadPostList, List<FollowUser> followersList, List<FollowUser> followingList) { 

    getSupportFragmentManager() 
      .beginTransaction() 
      .replace(R.id.frame_container, HomeUserProfileFragment.newInstance(post, followers, following,uploadPostList,followersList,followingList)) 
      .addToBackStack(null) 
      .commit(); 
}

所以我收到以下错误：

Error:(56, 50) error: incompatible types: List<UploadPost> cannot be converted to ArrayList<String> 
Error:(57, 48) error: incompatible types: List<FollowUser> cannot be converted to ArrayList<String> 
Error:(58, 49) error: incompatible types: List<FollowUser> cannot be converted to ArrayList<String>

'args.putStringArrayList'不以工作列表不是** StringArrayList ** –

答

使用此

Bundle args= new Bundle(); 
args.putParcelableArrayList(POST_TOTAL, postTotal); 
fragment.setArguments(bundle);

，而不是

Bundle args = new Bundle(); 
args.putString(POST_TOTAL, postTotal); 
fragment.setArguments(args);

这之后，您可以通过使用

取回该数据

Bundle extras = getIntent().getExtras(); 
ArrayList<ObjectName> arraylist = extras.getParcelableArrayList("arraylist");

这个问题似乎不是关于'String'值* postTotal *，所以你的（基本上是正确的）方法可能会被误解。还应该提到OP必须让每个问题类[实现Parcelable]（https://developer.android.com/reference/android/os/Parcelable.html） – 0X0nosugar

答

这是因为您有List s不是ArrayList s。

一个解决办法可能是包装你列到ArrayList其构造函数：

args.putStringArrayList(UPLOAD_POST_LIST, new ArrayList<>(uploadPostList));

答

我终于得到了一个解决方案。我不得不将Parcelable实现为UploadPost模型类和FollowUser模型类。由于这两个模型类是在第三个类中调用的，它们保存它们以及从服务器发送的其他参数，所以我必须将Parcelable实现到模型类。

然后：片段类的newInstance方法：

public static HomeUserProfileFragment newInstance(String yourId, String other_UserId, String name,String username,String userImage,String postTotal, String followersTotal 
     , String followingTotal, ArrayList<UploadPost> uploadPostList, ArrayList<FollowUser> followersList, ArrayList<FollowUser> followingList) { 

    HomeUserProfileFragment fragment = new HomeUserProfileFragment(); 
    Bundle args = new Bundle(); 
    args.putString(YOUR_USER_ID, yourId); // this holds the id of the user that his profile wants to be seen. 
    args.putString(VIEWER_USER_ID, other_UserId); // this holds the id of the user that want to see your profile. this Id is used to determine if the user is a friend or not.so if not a friend the follow button will be displayed. 
    args.putString(NAME,name); 
    args.putString(USERNAME, username); 
    args.putString(USER_IMAGE, userImage); 
    args.putString(POST_TOTAL, postTotal); 
    args.putString(FOLLOWERS_TOTAL, followersTotal); 
    args.putString(FOLLOWING_TOTAL, followingTotal); 
    args.putParcelableArrayList(UPLOAD_POST_LIST, uploadPostList); 
    args.putParcelableArrayList(FOLLOWERS_LIST, followersList); 
    args.putParcelableArrayList(FOLLOWING_LIST, followingList); 
    fragment.setArguments(args); 
    return fragment; 
}

而且Activity类调用片段：

@Override 
public void onClickUserProfile(String yourId, String viewerId, String name, String username, String userImage, String post, 
           String followers, String following, ArrayList<UploadPost> uploadPostList, ArrayList<FollowUser> followersList, ArrayList<FollowUser> followingList) { 
    this.yourId = yourId; 
    this.viewerId = viewerId; 
    getSupportFragmentManager() 
      .beginTransaction() 
      .replace(R.id.frame_container, HomeUserProfileFragment.newInstance(yourId,viewerId,name, username,userImage,post, followers, following,uploadPostList,followersList,followingList)) 
      .addToBackStack(null) 
      .commit(); 
}

这就是我的回答

不相容的类型：列表无法转换为ArrayList

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