public class SavaDataspUtil<T> {
    PRivate static final String TAG = "MainActivity";    private static SharedPreferences mSp = null;    private static SavaDataSPUtil mSavaDataSPUtil = null;    //創建單列標記    private static String flag=null;    //獲取保存數據標記    private String dataFlag=null;    private static Context mContext;    //初始化上下文    public static void initContext(Context context) {        mContext = context;    }    //私有的構造方法    private SavaDataSPUtil(String tag) {        this.dataFlag=tag;        this.flag = tag;        Log.i(TAG,"FLAG標志:"+flag);        mSp = mContext.getSharedPreferences(tag, Context.MODE_PRIVATE);    }    //根據不同的標簽創建不同的SavaDataSPUtil單列對象    public static SavaDataSPUtil getInstance(String tag) {        if (flag==null){            mSavaDataSPUtil=new SavaDataSPUtil(tag);            return mSavaDataSPUtil;        }else         if (flag!=null){            if (flag.equals(tag)){                return mSavaDataSPUtil;            }else            if (!flag.equals(tag)){                mSavaDataSPUtil=new SavaDataSPUtil(tag);                return mSavaDataSPUtil;            }        }       return null;    }    //保存數據    public void savaData(List<T> list) {        Gson gson = new Gson();        Type type = new TypeToken<List<T>>() {        }.getType();        String json = gson.toJson(list, type);        mSp.edit().putString(dataFlag, json).commit();    }    public List<T> getData() {        List<T> list=new ArrayList<>();        Gson gson=new Gson();        Type type=new TypeToken<List<T>>(){}.getType();        Log.i(TAG,"獲取數據的dataFlag標志:"+dataFlag);        String string = mSp.getString(dataFlag, "null");        list=gson.fromJson(string,type);        return list;    }}
根據不同的標記創建不同的單列對象，保存、獲取SharedPreference數據更加方便、快捷。