Android 片段 addToBackStack 无法与导航抽屉一起使用

Question

我创建了一个主页 activity，其中包含带有片段的导航抽屉 onclick。我已将 fragmentTransaction.addToBackStack(null).commit(); 包含在片段事务代码中。但它不会返回上一页，而是关闭应用程序。

在我的 MainActivity

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    FragmentManager fragmentManager = getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    // Handle navigation view item clicks here.
    int id = item.getItemId();
    RelativeLayout mainLayout=(RelativeLayout)findViewById(R.id.mainlayout);

  if (id == R.id.nav_project) {
        ProjectFragment fragment = new ProjectFragment();
        mainLayout.removeAllViews();
        fragmentTransaction.replace(R.id.mainlayout, fragment);
        fragmentTransaction.addToBackStack(null).commit();

    } 

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}
 @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

我的默认值Fragment

public class ProjectFragment extends Fragment {

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

            return v;
        }



}

谁能帮我解决这个问题。

Answer 1

感谢您的回复，很有帮助。基本上你需要添加一个片段到堆栈.

不使用replace()，而是使用fragmentTransaction的add方法。这会给你想要的效果。

简单示例：fragmentTransaction.add(R.id.mainlayout, fragment);

Android 片段 addToBackStack 无法与导航抽屉一起使用

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