返回上一个活动（PreferenceManager）(Return to the last activity (PreferenceManager))

 我想返回上一个活动，用户在关闭应用程序之前已关闭。 我已经实现了这个方法来传达3个活动，但在我的代码中有一些错误。 你有什么想法解决这个问题吗？ 
 
 MenuActivity（启动应用时打开） 
 
@Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        String lastActivity = ((Intent) PreferenceManager.getDefaultSharedPreferences(this)).getStringExtra("sent");

         if (lastActivity != null && lastActivity.equals("activity_2")){
                        {
                             Intent myIntentActivity1 = new Intent(menu.this,activity_2.class);
                               startActivity(myIntentActivity1);
                               }

                        } 

         if (lastActivity != null && lastActivity.equals("activity_3")){
                            {
                                 Intent myIntentActivity2 = new Intent(menu.this,activity_3.class);
                                   startActivity(myIntentActivity2);
                                   }

                            }

                            else {
                            Intent myIntentActivity3 = new Intent(menu.this,menu.class);
                               startActivity(myIntentActivity3);


                        }
 
 活动2 
 
 //一些代码 
 
@Override
    public void onResume(){
    super.onResume();
     Editor e = PreferenceManager.getDefaultSharedPreferences(this).edit();
        ((Intent) e).putExtra("sent", "activity_2");
        e.commit();
}
 
 活动3 
 
 //一些代码 
 
@Override
    public void onResume(){
    super.onResume();
     Editor e = PreferenceManager.getDefaultSharedPreferences(this).edit();
        ((Intent) e).putExtra("sent", "activity_3");
        e.commit();

    }

I would like to return to the last activity, the user has closed before closing down the application. I have implemented this method to communicate the 3 activities, but in my code there is something wrong. Do you have any idea to solve this problem?
 
MenuActivity (opens when the app is launched)
 
@Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        String lastActivity = ((Intent) PreferenceManager.getDefaultSharedPreferences(this)).getStringExtra("sent");

         if (lastActivity != null && lastActivity.equals("activity_2")){
                        {
                             Intent myIntentActivity1 = new Intent(menu.this,activity_2.class);
                               startActivity(myIntentActivity1);
                               }

                        } 

         if (lastActivity != null && lastActivity.equals("activity_3")){
                            {
                                 Intent myIntentActivity2 = new Intent(menu.this,activity_3.class);
                                   startActivity(myIntentActivity2);
                                   }

                            }

                            else {
                            Intent myIntentActivity3 = new Intent(menu.this,menu.class);
                               startActivity(myIntentActivity3);


                        }
 
Activity 2
 
//some code
 
@Override
    public void onResume(){
    super.onResume();
     Editor e = PreferenceManager.getDefaultSharedPreferences(this).edit();
        ((Intent) e).putExtra("sent", "activity_2");
        e.commit();
}
 
Activity 3
 
//some code
 
@Override
    public void onResume(){
    super.onResume();
     Editor e = PreferenceManager.getDefaultSharedPreferences(this).edit();
        ((Intent) e).putExtra("sent", "activity_3");
        e.commit();

    }

原文：https://stackoverflow.com/questions/20109003