对于Android世界来说,这几乎是新事物,我遇到了在片段之间传递参数的问题.我需要它来设置标签导航菜单中特定标签的ID.

在我的MainActivity.java中,我正在创建TabFragment的新实例,然后像这样启动事务：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ...
    mFragmentManager = getSupportFragmentManager();
    ...
    Fragment fragment = TabFragment.newInstance(0);
    fragmentTransaction(mFragmentManager, fragment);
    ...
}

哪里

private void fragmentTransaction(FragmentManager mFragmentManager, Fragment fragment) {
    FragmentTransaction fragmentTransaction = mFragmentManager.beginTransaction();
    fragmentTransaction.replace(R.id.containerView, fragment).commit();
}

(我将其封装在一种方法中,因为在其他地方也需要它.)

在我的TabFragment.java中,我编写了像这样的常规newInstance()方法：

public static TabFragment newInstance(int position) {
    Log.d("POSITION", "newInstance: " + position);
    TabFragment fragment = new TabFragment();
    Bundle args = new Bundle();
    args.putInt(ARG_POSITION, position);

    fragment.setArguments(args);

    return fragment;
}

问题在于,留在TabFragment.java中,我的getArguments()调用返回了一个空指针,因为它看起来像我的saveInstanceState也为空.

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    int position;
    try {
        position = savedInstanceState.getInt(ARG_POSITION);
    } catch (NullPointerException e) {
        position = -1;
    }
    Log.d("BUNDLE", "position: " + position);

    int position = getArguments().getInt(ARG_POSITION);

    ...
}

代码在getArguments()崩溃.
在评论该行时,我通过异常捕获发现捆绑包为空(位置= -1).

关于我做错什么的任何提示吗？
我一直在寻找类似的情况,但是我无法将这些解决方案应用于我的代码.
感谢您的任何帮助.

解决方法:

使用片段发送数据

    try {
         Bundle bundle = new Bundle();
         bundle.putString("key","value");    // data that you want to send
         LoginFragment fragment = new LoginFragment(); // Fragment that you want to call
         fragment.setArguments(bundle);
         FragmentTransaction fts = getSupportFragmentManager().beginTransaction();
         fts.replace(R.id.fragmentHolder, fragment);
         fts.addToBackStack(fragment.getClass().getSimpleName());
         fts.commit();
     }
    catch (Exception e){
        e.printStackTrace();
   }

通过其他片段中的Bundle接收数据

try {
      Bundle bundle = new Bundle();
      String data = bundle.getString("key");  // Receive data through key
    }
     catch (Exception e){
            e.printStackTrace();
        }