java - 通过包从 Activity 向 Fragment 传递数据时获取 null

Question

通过 bundle 传递数据时丢失数据，我得到

Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference at String bundlePassData = this.getArguments().getString("tagName");

这是我的代码示例。主要 Activity ->

 tagsView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
            Bundle bundle = new Bundle();
            TextView textView = (TextView) view.findViewById(R.id.tagName);
            String selectedItemName = textView.getText().toString();
            bundle.putString("tagName", selectedItemName);

            TaskAssignFragment taskAssignFragment = new TaskAssignFragment();
            taskAssignFragment.setArguments(bundle);

            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
            transaction.commit();

            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                    new TaskAssignFragment()).addToBackStack(null).commit();

            Log.i("ListView", selectedItemName);
        }
    });

任务分配 fragment ->

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_task_assign, container, false);
    TextView test = view.findViewById(R.id.testerView);

    String bundlePassData = this.getArguments().getString("tagName");
    test.setText(bundlePassData);

    return view;
}

我应该尝试接口(interface)吗？但如果我需要数据作为变量，而不仅仅是在函数中，因为我会在我的 fragment 中的更多地方使用它。

Answer 1

在您的代码中，您在替换时正在创建新 fragment 。

TaskAssignFragment taskAssignFragment = new TaskAssignFragment();
            taskAssignFragment.setArguments(bundle);

getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                    new TaskAssignFragment()).addToBackStack(null).commit();

使用您已创建的 fragment 实例并在其中设置参数

  getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                   taskAssignFragment).addToBackStack(null).commit();