java - Sharedpreferences 保存后返回空值

Question

我有一个带有两个单选按钮的单选按钮。我想选择一个单选按钮并点击保存，这样当我返回时，相同的单选按钮就会被选中。问题是，即使在我点击保存 onCreate 中的 sharedpreferences 之后，它也总是返回 null。我知道保存功能正在执行，因为 toast 运行并且我在控制台中打印了 System.out.println。

public void saveSettings(View view)
{
    Toast.makeText(getApplicationContext(), "Settings Saved", Toast.LENGTH_LONG).show();

    //DETERMINE WHICH RADIO BUTTON IS SELECTED
    RadioButton lbSetting = (RadioButton)findViewById(R.id.weightSettingLB);
    RadioButton kgSetting = (RadioButton)findViewById(R.id.weightSettingKG);
    if(lbSetting.isChecked())
    {
        weightSetting = "lb";
    }
    if(kgSetting.isChecked())
    {
        weightSetting = "kg";
    }

    System.out.println("The " + weightSetting + " radio button has been selected.");

    //SAVE WEIGHT SETTING BETWEEN LB/KG
    settingsPrefString = getSharedPreferences(weightSetting, 0);
    SharedPreferences.Editor editor = settingsPrefString.edit();
    editor.putString("weightSetting", weightSetting);
    editor.commit();
}

在我的 onCreate 中，我尝试将保存的数据检索为

if(settingsPrefString != null)
{
    weightSetting = settingsPrefString.getString("weightSetting", "Couldn't load data!");
}
if(settingsPrefString == null)
{
    System.out.println("settingsPrefString is NULL!");
}

即使在我点击保存之后，sharedpreferences 总是返回为 null。

Answer 1

在需要时调用这些函数:

private void savePreferences(String key, String value){
    SharedPreferences sharedPreferences = getSharedPreferences("weightSetting", MODE_PRIVATE);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putString(key, value);
    editor.commit();
   }


  private String loadPreferences(String key){
    SharedPreferences sharedPreferences = getSharedPreferences("weightSetting", MODE_PRIVATE);
    String load = sharedPreferences.getString(key, "");
    return load;

   }
}

例如:

savePreferences("selected", "lb");

和

String s = loadPreferences("selected);