Question

我是Fragments的新手。我试过简单的片段示例。但它会引发错误。我不知道出了什么问题。

public class NewActivity extends Activity {
    int mStackLevel = 1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (savedInstanceState == null) {
            Fragment newFragment = NewFragment
                    .newInstance(mStackLevel);
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.add(R.id.simple_fragment, newFragment).commit();
        } else {
            mStackLevel = savedInstanceState.getInt("level");
        }
    }
    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt("level", mStackLevel);
    }
    public static class NewFragment extends Fragment {
        int mNum;
        Context context;

        static NewFragment newInstance(int num) {
            NewFragment f = new NewFragment();

            // Supply num input as an argument.
            Bundle args = new Bundle();
            args.putInt("num", num);
            f.setArguments(args);

            return f;
        }

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            mNum = getArguments() != null ? getArguments().getInt("num") : 1;
            context = getActivity();
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View v = inflater.inflate(R.layout.example_fragment, container,
                    false);         
            return v;
        }
    }

}

我的logcat显示：

java.lang.RuntimeException：无法启动活动ComponentInfo {com.example.FragmentExample / com.example.FragmentExample.NewActivity}：java.lang.IllegalArgumentException：找不到片段NewFragment {40ff0850＃0 id的id 0x7f07003c的视图= 0x7f07003c}

Answer 1

ft.add(R.id.simple_fragment, newFragment).commit();

您错过了setContentView您的活动。如果没有View层次结构，则无法添加片段。

注意：您的片段由活动托管。因此，您需要先将内容设置为活动。

Answer 2

只需用您的方法替换此方法

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(Your_layout_file);

        if (savedInstanceState == null) {
            Fragment newFragment = NewFragment
                    .newInstance(mStackLevel);
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.add(R.id.simple_fragment, newFragment).commit();
        } else {
            mStackLevel = savedInstanceState.getInt("level");
        }
    }

你错过了这一行setContentView(Your_layout_file);

Answer 3

这个答案强调了可能发生的一个愚蠢的错误，即在嵌套片段或将活动转换为片段时出现的错误。

如果您尝试使用fragmentManager替换片段中的片段，但不会使父片段膨胀，则可能会导致问题。

在 BaseFragment.java OnCreateView中：

if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .replace(R.id.container, new DifferentFragment())
                    .commit();
        }

return super.onCreateView(inflater, container, savedInstanceState);

替换super.onCreateView(inflater, container, savedInstanceState); 为片段充气正确的布局：

        return inflater.inflate(R.layout.base_fragment, container, false);

IllegalArgumentException：找不到片段的id 0x7f07003c的视图

3 个答案: