Question

我正在尝试学习android中的sharedPreferences并为此编写了一小段代码。但是一旦我执行它，应用程序就不会显示任何输出。

这是我的偏好类：

<Text>
   <Text>We</Text><Text>Are</Text><Text>Inline</Text>
</Text>

这是我使用这个课程的主要活动：

public class SharedPreferncesExecutor {
    public static final String PREFS_NAME = "AOP_PREFS";
    public static final String PREFS_KEY = "AOP_PREFS_String";

    public SharedPreferncesExecutor() {
        super();
    }

    public void save(Context context, String Key, String Value) {
        SharedPreferences settings;
        SharedPreferences.Editor editor;

        //settings = PreferenceManager.getDefaultSharedPreferences(context);
        settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE); //1
        editor = settings.edit(); //2

        editor.putString(Key, Value); //3

        editor.commit(); //4
    }

    public String getValue(Context context,String key) {
        SharedPreferences settings;
        String text;

        //settings = PreferenceManager.getDefaultSharedPreferences(context);
        settings = context.getSharedPreferences(key, Context.MODE_PRIVATE);
        text = settings.getString(key, null);
        return text;
    }

    public void clearSharedPreference(Context context) {
        SharedPreferences settings;
        SharedPreferences.Editor editor;

        //settings = PreferenceManager.getDefaultSharedPreferences(context);
        settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
        editor = settings.edit();

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

    public void removeValue(Context context) {
        SharedPreferences settings;
        SharedPreferences.Editor editor;

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

        editor.remove(PREFS_KEY);
        editor.commit();
    }
}

这是我的activityMain.xml：

public class MainActivity extends Activity implements View.OnClickListener{

    ImageButton bLogOut,bHowItWorks;

    TextView SchoolDetail,AllClassDetail,TotalStudents,OneStudentDetail;
    //this is for having access to userlocalstore to save/remove local data to user phone during login or Log out. So that if logout is pressed
    //the data is wiped off the local storage on user mobile
    UserLocalStore userLocalStore;

    //Added to get the data from sharedPreferencesExecutor
    private SharedPreferncesExecutor sharedPreference;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
        //WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setContentView(R.layout.activity_main);

        //etEmail= (EditText)findViewById(R.id.etEmail);
        //etPhoneNumber =(EditText)findViewById(R.id.etPhoneNumber);
        bLogOut = (ImageButton) findViewById(R.id.bLogOut);

        bLogOut.setOnClickListener(this);

        userLocalStore = new UserLocalStore(this);
        //added for QR codes scanner
        bHowItWorks = (ImageButton) findViewById(R.id.bHowItWorks);
        bHowItWorks.setOnClickListener(this);
        SchoolDetail = (TextView)findViewById(R.id.SchoolDetail);


        //Added to get the data from sharedPreferencesExecutor
        sharedPreference = new SharedPreferncesExecutor();
        Activity context = this;
        sharedPreference.save(context,"SchoolData","KV Station;;;class1-secA;;;class1-secB;;;class1-secC;;;class4;;;class2-secA;;;class2-secB;;;class2-secC;;;class3-secA;;;class3-secB;;;class3-secC;;;class4-secA;;;class4-secB;;;class4-secC;;;class5-secA;;;class5-secB;;;class5-secC");
        String SchoolData = sharedPreference.getValue(context,"SchoolData");
        SchoolDetail.setText(SchoolData);

    }

    @Override
    public void onClick(View v) {
        switch(v.getId()){
            case R.id.bLogOut:
                userLocalStore.clearUserData();
                userLocalStore.setUserLoggedIn(false);

                startActivity(new Intent(this,Login.class));

                break;

            case R.id.bHowItWorks:
                startActivity(new Intent(this,howItWorks.class));
                break;
        }
    }

    @Override
    protected void onStart() {
        super.onStart();

        if (authenticate() == true) {
            displayUserDetails();
        }
        else{
            Intent intentLogin = new Intent(MainActivity.this,Login.class);
            intentLogin.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK);
            startActivity(intentLogin);
        }
    }

    public boolean authenticate(){
        return userLocalStore.getUserLoggedIn();
    }

    public void displayUserDetails(){
        //User user = userLocalStore.getLoggedInUser();
        //etEmail.setText(user.Email);
        //etPhoneNumber.setText(user.PhoneNumber + "");

    }
}

执行后，我没有收到任何数据。如果我遗失了某些内容，请告诉我

Answer 1

检查您的SharedPreferencesExecutor

代码

public String getValue(Context context,String key) {
    SharedPreferences settings;
    String text;

    //settings = PreferenceManager.getDefaultSharedPreferences(context);
    // here you are passing 'key' by mistake change it to 'PREFS_NAME'
    settings = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
    text = settings.getString(key, null);
    return text;
}

肯定它会工作..

在Android中使用getPreference时没有输出

1 个答案: