Question

这是我的活动课

 protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_dashboard);

            username = getIntent().getStringExtra("username");
            password = getIntent().getStringExtra("password");

            DashbordFragment f = new DashbordFragment();
            Bundle b = new Bundle();
            b.putString("username",username);
            b.putString("password",password);
            f.setArguments(b);

创建一个片段并使用bundle将其传递给片段f

            DashbordFragment fragment = f;
            android.support.v4.app.FragmentTransaction fragmentTransaction =
                    getSupportFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.fragment_container, fragment);
            fragmentTransaction.commit();
            }

点击菜单项时更改片段

         public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            int id = item.getItemId();
            Fragment fragment=null;
            if(id == R.id.nav_dashboard){
                 fragment = new DashbordFragment();
            }
            else if (id == R.id.nav_inbox){
                fragment = new InboxFragment();
            }

            if (fragment != null) {
                android.support.v4.app.FragmentTransaction 
               fragmentTransaction =
                        getSupportFragmentManager().beginTransaction();

这是为了替换

                fragmentTransaction.replace(R.id.fragment_container, 
               fragment);
                fragmentTransaction.commit();
            }
            DrawerLayout drawer = (DrawerLayout) 
             findViewById(R.id.drawer_layout);
            drawer.closeDrawer(GravityCompat.START);
            return false;
        }

Answer 1

您是否尝试在FragmentClass上添加或覆盖saveInstanceState？仅当您想依赖存储状态时才建议您使用实例变量

@Override public void onSaveInstanceState(Bundle outState) {
  super.onSaveInstanceState(outState);
  // Save some state!
}

Answer 2

您可以在应用程序中使用共享首选项来存储用户名和密码。通过使用它，您可以随时随地访问整个应用程序中保存的数据。

这将为您提供相同的基本概念：Shared Preference

保存数据：

SharedPreferences.Editor editor = 
getActivity().getSharedPreferences(prefKey, MODE_PRIVATE).edit();
editor.putString("username", "abc"); 
editor.putString("password", "123"); 
editor.apply();

要检索数据：

SharedPreferences prefs = getActivity().getSharedPreferences(prefKey, 
MODE_PRIVATE);
if (prefs.contains("username")&&(prefs.contains("password"))){
        String userName= prefs.getString("username",null);
        String usrPassword = prefs.getString("paswword",null);
        if((userName!=null) && (usrPassword!= null)) {
          //whatever you need to do with the obtained data
        }
    }

当我在片段之间交换时，前一个片段中的数据正在消失？

2 个答案: