关闭应用程序后如何保持选中单选按钮 - android studio

Question

我是在 Android Studio 中编码的新手，我刚刚了解了共享偏好。 我的老师给我布置了一个单选按钮组（RadioGroup）的作业，当您选中其中一个按钮时，关闭应用程序，再次打开它，该按钮将保持选中状态。

就像您将使用SharedPrefrences保存EditText答案一样，我需要使用SharedPrefrences保存一个RadioButton 。

正如我所说，我是新手，所以请保持简单的答案:)

--已解决--谢谢大家的回答！ 感谢您的评论，我找到了我的解决方案！ :D

Answer 1

首先，您要像这样将侦听器设置为RadioGroup ：

RadioGroup radioGroup = (RadioGroup) findViewById(R.id.yourRadioGroup);        
    radioGroup.setOnCheckedChangeListener(new OnCheckedChangeListener() 
    {
        @Override
        public void onCheckedChanged(RadioGroup group, int checkedId) {
            // save id into your SharedPreferences
        }
    });

然后你可以在 onCreate() 中从共享首选项中恢复它并调用radioGroup.check(id); .
所以代码看起来像这样：

SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this);
int checkedId = sharedPrefs.getInt("your key", 0);
radioGroup.check(checkedId);  

请注意，此代码已简化。 您需要添加检查等

Answer 2

尝试这个，

    RadioGroup radioGroup = findViewById(R.id.radio_gropup);
    final SharedPreferences preferences = getSharedPreferences("saved", 0);

    radioGroup.check(preferences.getInt("CheckedId", 0));

    radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(RadioGroup group, int checkedId) {
            SharedPreferences.Editor editor = preferences.edit();
            editor.putInt("CheckedId", checkedId);
            editor.apply();
        }
    });

Answer 3

这是您应该如何在单选组上获取onCheckChangeListener以获取其中的选定单选按钮！

笔记！！！ 应该为所有内部无线电按钮提供 ID

radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener()
    {
        public void onCheckedChanged(RadioGroup group, int checkedId) {
            // checkedId is the RadioButton selected
            RadioButton rb=(RadioButton)findViewById(checkedId);

            //textViewChoice.setText("You Selected " + rb.getText());
           // here the rb.getText() will give you the text and you can send it to your
           //sharedPreference with a new key value like you did with the editText values
        }
    });

当你的应用程序启动，你可以在你的onCreate（）由sharefPreference检查值保存然后拿到单选按钮，并设置其属性isSelected为真！ 我希望这足够简单！

Answer 4

public class MainActivity extends AppCompatActivity {
   // this will be key for the key value pair
   public static final String BUTTON_STATE = "Button_State";
   // this is name of shared preferences file, must be same whenever accessing
   // the key value pair.
   public static final String MyPREFERENCES = "MyPrefs" ;

   SharedPreferences sharedpreferences;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      // helper method to open up the file.
      sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
      // grab the last saved state here on each activity start
      Boolean lastButtonState = sharedpreferences.getBoolean(BUTTON_STATE, false)
      RadioButton rb = (RadioButton) findViewById(R.id.radio_button);
      // restore previous state
      rb.setChecked(lastButtonState);
      // set a listener
      rb.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            // call this to enable editing of the shared preferences file
            // in the event of a change
            SharedPreferences.Editor editor = sharedpreferences.edit();
            Boolean isChecked = rb.isChecked();
            // use this to add the new state
            editor.putBoolean(BUTTON_STATE, isChecked);
            // save
            editor.apply();
         }
      });
   }
}