Question

我有复选框，如果我单击复选框并登录然后用户名和密码保存在sharedpreferences ..并移动到FirstScreen活动....然后如果我关闭应用程序并重新启动然后应用程序必须直接转移到FirstScrren ...这对我来说很好并且运作良好......

问题::如果我在输入详细信息后点击并单击复选框...如果我退出并转到LoginScreen，则移至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为空...）

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

您的偏好设置键不匹配：一个活动中的“User_Shared”和另一个活动中的“user_StoreShared”;与“Pass_Shared”和“password_StoreShared”相同。这些键必须命名相同。所以，在你的第二个活动中，改变这个：

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

到此：

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

Answer 2

我认为你的问题只是TextViews显示它的最后一个值，就像按下后退按钮时，刚恢复的活动没有重新创建，所以，尝试设置它的值在返回时或在移至FirstScreen活动之前。

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);

}

在转到FirstScreen活动之前：

  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);
        }
    });

您也可以覆盖活动的onResume方法：

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

ps 无论这有助于您解决我们的问题，您都不能将null作为默认值传递给SharedPreferences对象，您必须通过在""的情况下Strings（可能这是它为您提供的当前行为），只需将其修改为以下内容：

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

删除值后共享偏好并再次启动appilcation显示值

2 个答案: