1. 确认 Dialog Fragment 的布局文件是否正确，是否包含正确的视图元素。
2. 在应用程序代码中，确保正确地实例化 Dialog Fragment 并将其添加到 Activity 或 Fragment 的视图层次结构中。
3. 确保在Fragment中使用getChildFragmentManager()，在Activity中使用getSupportFragmentManager()。 示例代码：
4. 布局文件

2. 创建 Dialog Fragment：

public class MyDialogFragment extends DialogFragment { private EditText mEditText; private String mText;

public MyDialogFragment() {
    // Required empty public constructor
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Get the layout inflater
    LayoutInflater inflater = getActivity().getLayoutInflater();

    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_my_dialog, null);

    mEditText = (EditText) view.findViewById(R.id.editText);

    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
    builder.setView(view)
            .setTitle("Dialog Fragment Title")
            .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    mText = mEditText.getText().toString();
                }
            })
            .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // do nothing
                }
            });
    AlertDialog dialog = builder.create();
    setCancelable(false);
}

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    return super.onCreateDialog(savedInstanceState);
}

}

3. 在 Activity 中调用 Dialog Fragment

MyDialogFragment dialogFragment = new MyDialogFragment(); dialogFragment.show(getSupportFragmentManager(), "dialog");