我使用相同的方式保存和检索字符串，但这里我使用HashSet作为数组列表的中介

使用HashSet保存arrayList到SharedPreferences:

1-我们创建SharedPreferences变量(在数组发生变化的地方)

2 -我们将数组列表转换为HashSet

3 -然后放入stringSet并应用

4 -你在HashSet中获取stringset并重新创建ArrayList来设置HashSet。

public class MainActivity extends AppCompatActivity {
    ArrayList<String> arrayList = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        SharedPreferences prefs = this.getSharedPreferences("com.example.nec.myapplication", Context.MODE_PRIVATE);

        HashSet<String> set = new HashSet(arrayList);
        prefs.edit().putStringSet("names", set).apply();


        set = (HashSet<String>) prefs.getStringSet("names", null);
        arrayList = new ArrayList(set);

        Log.i("array list", arrayList.toString());
    }
}

    public  void saveUserName(Context con,String username)
    {
        try
        {
            usernameSharedPreferences= PreferenceManager.getDefaultSharedPreferences(con);
            usernameEditor = usernameSharedPreferences.edit();
            usernameEditor.putInt(PREFS_KEY_SIZE,(USERNAME.size()+1)); 
            int size=USERNAME.size();//USERNAME is arrayList
            usernameEditor.putString(PREFS_KEY_USERNAME+size,username);
            usernameEditor.commit();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }

    }
    public void loadUserName(Context con)
    {  
        try
        {
            usernameSharedPreferences= PreferenceManager.getDefaultSharedPreferences(con);
            size=usernameSharedPreferences.getInt(PREFS_KEY_SIZE,size);
            USERNAME.clear();
            for(int i=0;i<size;i++)
            { 
                String username1="";
                username1=usernameSharedPreferences.getString(PREFS_KEY_USERNAME+i,username1);
                USERNAME.add(username1);
            }
            usernameArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, USERNAME);
            username.setAdapter(usernameArrayAdapter);
            username.setThreshold(0);

        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }

//Set the values
intent.putParcelableArrayListExtra("key",collection);

//Retrieve the values
ArrayList<OnlineMember> onlineMembers = data.getParcelableArrayListExtra("key");

使用这个自定义类:

public class SharedPreferencesUtil {

    public static void pushStringList(SharedPreferences sharedPref, 
                                      List<String> list, String uniqueListName) {

        SharedPreferences.Editor editor = sharedPref.edit();
        editor.putInt(uniqueListName + "_size", list.size());

        for (int i = 0; i < list.size(); i++) {
            editor.remove(uniqueListName + i);
            editor.putString(uniqueListName + i, list.get(i));
        }
        editor.apply();
    }

    public static List<String> pullStringList(SharedPreferences sharedPref, 
                                              String uniqueListName) {

        List<String> result = new ArrayList<>();
        int size = sharedPref.getInt(uniqueListName + "_size", 0);

        for (int i = 0; i < size; i++) {
            result.add(sharedPref.getString(uniqueListName + i, null));
        }
        return result;
    }
}

使用方法:

SharedPreferences sharedPref = getPreferences(Context.MODE_PRIVATE);
SharedPreferencesUtil.pushStringList(sharedPref, list, getString(R.string.list_name));
List<String> list = SharedPreferencesUtil.pullStringList(sharedPref, getString(R.string.list_name));

你可以使用Gson库保存字符串和自定义数组列表。

首先你需要创建一个函数来保存数组列表到SharedPreferences。

public void saveListInLocal(ArrayList<String> list, String key) {

        SharedPreferences prefs = getSharedPreferences("AppName", Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = prefs.edit();
        Gson gson = new Gson();
        String json = gson.toJson(list);
        editor.putString(key, json);
        editor.apply();     // This line is IMPORTANT !!!

    }

你需要创建一个函数来从SharedPreferences获取数组列表。

public ArrayList<String> getListFromLocal(String key)
{
    SharedPreferences prefs = getSharedPreferences("AppName", Context.MODE_PRIVATE);
    Gson gson = new Gson();
    String json = prefs.getString(key, null);
    Type type = new TypeToken<ArrayList<String>>() {}.getType();
    return gson.fromJson(json, type);

}

如何调用保存和检索数组列表函数。

ArrayList<String> listSave=new ArrayList<>();
listSave.add("test1"));
listSave.add("test2"));
saveListInLocal(listSave,"key");
Log.e("saveArrayList:","Save ArrayList success");
ArrayList<String> listGet=new ArrayList<>();
listGet=getListFromLocal("key");
Log.e("getArrayList:","Get ArrayList size"+listGet.size());

不要忘记在你的应用级别build.gradle中添加gson库。

实现“com.google.code.gson: gson: 2.8.2”

使用Kotlin，对于简单的数组和列表，你可以这样做:

class MyPrefs(context: Context) {
    val prefs = context.getSharedPreferences("x.y.z.PREFS_FILENAME", 0)
    var listOfFloats: List<Float>
        get() = prefs.getString("listOfFloats", "").split(",").map { it.toFloat() }
        set(value) = prefs.edit().putString("listOfFloats", value.joinToString(",")).apply()
}

然后轻松访问首选项:

MyPrefs(context).listOfFloats = ....
val list = MyPrefs(context).listOfFloats