按下后退按钮时保存状态

Question

我正在开发一个Android应用程序.如果我按后退按钮我的应用程序的状态应该保存.什么我应该使用保存状态..am困惑与所有这些onPause(),onResume()或onRestoresavedInstance()??? 我应该使用哪些来保存我的应用程序状态？例如,当我按退出按钮时,我的整个应用程序应退出我已使用完成()？

   public void onCreate(Bundle savedInstanceState)
   {   

    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    s1=(Button)findViewById(R.id.sn1);
    s1.setOnClickListener(this);
    LoadPreferences();
    s1.setEnabled(false);
    }

    public void SavePreferences()
 {
        SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putBoolean("state", s1.isEnabled());
       }
 public void LoadPreferences()
 {
     System.out.println("LoadPrefe");
        SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
        Boolean  state = sharedPreferences.getBoolean("state", false);
        s1.setEnabled(state);
       }
 @Override
 public void onBackPressed()
 {
    System.out.println("backbutton");
    SavePreferences();
     super.onBackPressed();
 }

Answer 1

您需要做的是,而不是使用KeyCode Back,您已在Activity中覆盖以下方法,

@Override
public void onBackPressed() {

    super.onBackPressed();
}

并使用SharedPrefrence保存Button的状态,下次当您输入Activity时,从Sharedpreference获取值并相应地设置按钮的启用状态.

例,

private void SavePreferences(){
    SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putBoolean("state", button.isEnabled());
    editor.commit();   // I missed to save the data to preference here,. 
   }

   private void LoadPreferences(){
    SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
    Boolean  state = sharedPreferences.getBoolean("state", false);
    button.setEnabled(state);
   }

   @Override
public void onBackPressed() {
    SavePreferences();
    super.onBackPressed();
}

onCreate(Bundle savedInstanceState)
{
   //just a rough sketch of where you should load the data
    LoadPreferences();
}