删除值后共享首选项并再次启动应用程序它显示值

Question

我有复选框，如果我点击复选框并登录然后用户名和密码保存在共享首选项中..并移动到 FirstScreen Activity..然后如果我关闭应用程序并再次重新启动然后应用程序必须直接移动到 FirstScrren ...这对我来说很好并且运行良好...

issue:: 如果我在输入详细信息后登录并单击复选框...如果我注销并转到 LoginScreen，则会移动到 firstScrren 通过删除共享首选项中的值......它也很好......但是如果我按下后退按钮并再次打开应用程序然后它显示登录的值......（在这种情况下它必须是空的......）

public class LoginActivity extends ActionBarActivity {

 EditText username,passwordField;
 Button login,registerButton;
 CheckBox check;

    SharedPreferences settings;
    SharedPreferences.Editor editor;
    String userStored;
    String passwordStored;
     boolean checked =false;
     boolean checkboxvalue;
     public static final String PREFS_NAME = "Shared_File";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);



    username =(EditText)findViewById(R.id.username);
    passwordField =(EditText)findViewById(R.id.passwordField);      
    check = (CheckBox) findViewById(R.id.checkBox);     

    login = (Button)findViewById(R.id.login);
    login.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub


             if (check.isChecked()) {

                checked = true;

                settings = getSharedPreferences(PREFS_NAME,Context.MODE_PRIVATE);

                editor = settings.edit();                                   
                editor.putString("User_Shared", username.getText().toString());
                editor.putString("Pass_Shared", passwordField.getText().toString());                
                editor.putBoolean("Checkbox_Click", true);

                editor.commit();

                userStored = settings.getString("User_Shared",null);
                passwordStored =settings.getString("Pass_Shared", null);                     
                checkboxvalue = settings.getBoolean("Checkbox_Click", false);

                System.out.println("userStored :::" +userStored + " ::::pasword ::::" +passwordStored + ":::check" + checkboxvalue );



            }               



             Intent intent =  new Intent(getApplicationContext(),FirstScreen.class);
             startActivity(intent);


        }
    });



}


@Override
protected void onStart() {
    // TODO Auto-generated method stub
    super.onStart();



    if ( userStored != null  &&  ! userStored.isEmpty()) {

         username.setText(userStored);
         passwordField.setText(passwordStored);          

         Intent intent1 = new Intent (getApplicationContext(), FirstScreen.class);
         startActivity(intent1);

    }


    else{

         username.setText("");
         passwordField.setText(""); 

    }


}

}




public class FirstScreen extends Activity {


    Button logout;
    User myApplication;  
    SharedPreferences settings;
    SharedPreferences.Editor editor;
    public static final String PREFS_NAME = "Shared_File";

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.firstscreen);


  myApplication = (User) getApplicationContext();

  logout =(Button)findViewById(R.id.logout);

  logout.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub


        settings =getSharedPreferences(PREFS_NAME,Context.MODE_PRIVATE);
        editor = settings.edit();   

           try {

               editor.remove("User_Shared");
               editor.remove("Pass_Shared");
               editor.remove("Checkbox_Click");

        //     editor.clear();
               editor.commit();
        }

           catch (NullPointerException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } 
           catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 


    Intent intent = new Intent(getApplicationContext(), LoginActivity.class);
            //intent.putExtra("Logout", logout);

        startActivity(intent);



    }
});



}

@Override
public void onBackPressed() {
    // TODO Auto-generated method stub
    super.onBackPressed();

     moveTaskToBack(true);

}
}

Answer 1

您的首选项键不匹配："User_Shared" 在一个 activity 和 "user_StoreShared" 在另一个；与 "Pass_Shared" 和 "password_StoreShared" 相同。这些键必须命名相同。因此，在您的第二个 activity 中，将此更改为：

editor.remove("user_StoreShared");
editor.remove("password_StoreShared");

对此：

editor.remove("User_Shared");
editor.remove("Pass_Shared");

Answer 2

我认为你的问题只是 TextViews 显示了它的最后一个值，因为当按下 Back 按钮时，activity 刚刚恢复而不是重新创建，因此，尝试在返回时或移动到 FirstScreen activity.

之前设置它的值

通过onBackPressed :

@Override
public void onBackPressed() {
    // TODO Auto-generated method stub
    super.onBackPressed();
    LoginActivity.username.setText(""); but in this case they must be public static in the LoginActivity
    LoginActivity.passwordField.setText(""); 
    moveTaskToBack(true);

}

移动到第一个屏幕之前activity:

  login.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
                 .
                 .
                 .
           username.setText("");
           passwordField.setText(""); 
           Intent intent = new Intent(getApplicationContext(),FirstScreen.class);
           startActivity(intent);
        }
    });

您也可以 重写 Activity 的 onResume 方法：

@Override
public void onResume(){
    super.onResume();
    username.setText("");
    passwordField.setText(""); 
}

p.s. 无论这是否帮助您解决问题，您绝不能将 null 作为默认值传递给 SharedPreferences 对象，你必须在 Strings 的情况下传递 "" （可能这就是它给你当前行为的原因），只需将其修改为以下内容：

 userStored = settings.getString("User_Shared","");
 passwordStored =settings.getString("Pass_Shared", "");

删除值后共享首选项并再次启动应用程序它显示值

sharedpreferences after removing the values and launches appilcation again it showing values

android

sharedpreferences