android 不清除 sharedpreference

Question

我想清除我在第一个 Activity 中放置的所有 sharedpref，并在第二个 Activity 中将其删除。但是清除功能不起作用..这是我的代码

public class MyActivity extends Activity implements View.OnClickListener {
    /**
     * Called when the activity is first created.
     */

    public static final String PREFS_NAME = "ResumePrefs";

    SharedPreferences settings;
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ((Button)findViewById(R.id.button)).setOnClickListener(this);

    }

    @Override
    protected void onResume() {
        try{
            Toast. makeText(this,settings.getString("answer_id",""),Toast.LENGTH_LONG).show();
        }catch (Exception e){
            Toast.makeText(this,e.toString(),Toast.LENGTH_LONG).show();
        }
        super.onResume();
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.button:
                 settings = getSharedPreferences(PREFS_NAME, 1);
                SharedPreferences.Editor editor = settings.edit();
                editor.putString("answer_id", "This is a test");
                editor.commit();
                     Intent intent = new Intent(this,destroyPref.class);
                startActivity(intent);
                break;
        }
    }
}

和我的第二个 Activity :

public class destroyPref extends Activity {
    public static final String PREFS_NAME = "ResumePrefs";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.destroy);

    }

    @Override
    public void onBackPressed() {
        SharedPreferences settings = this.getSharedPreferences(PREFS_NAME,1);
        settings.edit().clear();
        settings.edit().commit();
        super.onBackPressed();
    }

    @Override
    protected void onResume() {
        SharedPreferences settings = this.getSharedPreferences(PREFS_NAME,1);
        settings.edit().clear();
        settings.edit().commit();
        super.onResume();
    }
}

一旦我按下后退按钮，我将返回到主要 Activity 并期望清除首选项值，除非我再次按下该按钮。我尝试了 bot backpress 和 resume 但 sharedpref 值仍然存在..我错过了什么吗？谢谢。

Answer 1

试试这个:

SharedPreferences.Editor editor = settings.edit();
editor.clear();
editor.commit();

谢谢。