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嘿，我正在尝试将 onSharedPreference 侦听器添加到 n 片段中。如果更改完成（在设置中切换），它应该调节 Fragment 中 NumberPicker 的值也会更改（0 或 1）。

听众的问题：它只工作前 5-10 次，然后它不再被调用（我想）？-> 在我的片段的重要代码之后没有对 NumberPicker 进行任何更改：

public class FragmentTwo extends Fragment {

private EditText mEnterWeight;
private NumberPicker mUnitPicker;
private TextView mConverted;
private int pick;
private String convertedWeightMessage;
private Double enteredWeight;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.fragment_two, container, false);
    mEnterWeight = (EditText) view.findViewById(R.id.WCenterWeight);
    mUnitPicker = (NumberPicker) view.findViewById(R.id.WCunitPicker);
    mConverted = (TextView) view.findViewById(R.id.WCconverted);
    initialiseUnitPicker(); 
    //some stuff 
    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
    SharedPreferences.OnSharedPreferenceChangeListener listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
        public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
            // listener implementation      

            if(key.equals("SwitchMainUnit")) {
                Boolean kg = prefs.getBoolean("SwitchMainUnit", true);
                    if(kg)
                        mUnitPicker.setValue(0);
                        else mUnitPicker.setValue(1);
            }

        }
    };
    prefs.registerOnSharedPreferenceChangeListener(listener);
 return view;
}

文档说我需要将 onResume() 和 onPause() 更改为：

@Override
protected void onResume() {
super.onResume();
getPreferenceScreen().getSharedPreferences()
        .registerOnSharedPreferenceChangeListener(this);
}

@Override
protected void onPause() {
super.onPause();
getPreferenceScreen().getSharedPreferences()
        .unregisterOnSharedPreferenceChangeListener(this);
}

但是我需要在哪里添加这些？当我尝试将其添加到 Fragment 时出现错误。

感谢您的帮助；我自己没有找到任何解决方案..：/

4

1 回答 1

4

文件说

注意：当您调用 registerOnSharedPreferenceChangeListener() 时，首选项管理器当前不存储对侦听器的强引用

我建议您将您的实例存储SharedPreferences.OnSharedPreferenceChangeListener listener为onCreateView.

示例代码：

公共类 FragmentTwo 扩展 Fragment {

private EditText mEnterWeight;
private NumberPicker mUnitPicker;
private TextView mConverted;
private int pick;
private String convertedWeightMessage;
private Double enteredWeight;
SharedPreferences.OnSharedPreferenceChangeListener listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
    public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
        // listener implementation      

        if (key.equals("SwitchMainUnit")) {
            Boolean kg = prefs.getBoolean("SwitchMainUnit", true);
            if (kg) mUnitPicker.setValue(0);
            else mUnitPicker.setValue(1);
        }

    }
};
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.fragment_two, container, false);
    mEnterWeight = (EditText) view.findViewById(R.id.WCenterWeight);
    mUnitPicker = (NumberPicker) view.findViewById(R.id.WCunitPicker);
    mConverted = (TextView) view.findViewById(R.id.WCconverted);
    initialiseUnitPicker();
    //some stuff 
    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
    prefs.registerOnSharedPreferenceChangeListener(listener);
    return view;
}
于 2015-11-03T21:28:40.990 回答