Question

activity_main 中的RecyclerView有三个复选框， activity_main 底部是一个按钮，点击该按钮可保存checkbox状态（ true 或 false ）及其适配器位置hashmap。位置是关键，状态是值。两者都转换为String。我想将其保存到sharedpreferences。我发现原始数据类型可以保存到shared preferences。是否存在一种保存hashmap的方法。

RecyclerAdapter.java：

public class RecyclerHolder extends RecyclerView.ViewHolder {
    AnimCheckBox checkBox;
    checkBox = (AnimCheckBox) itemView.findViewById(R.id.checkBox);
    checkBox.setChecked(false);
    public RecyclerHolder(final View itemView) {
        super(itemView);
        checkBox.setOnCheckedChangeListener(new AnimCheckBox.OnCheckedChangeListener() {
            @Override
            public void onChange(boolean checked) {
                checkboxclick = true;
                if (checkBox.isChecked()) {
                    boolean check = true;
                    clicked_position = getAdapterPosition();
                    String position = Integer.toString(clicked_position);
                    String check_status = Boolean.toString(check);
                    hashMap.put(position, check_status);
                } else {
                    String removekey = String.valueOf(getAdapterPosition());
                    if (hashMap.containsKey(removekey)) {
                        hashMap.remove(removekey);
                    }
                }
            }
        });

        SharedPreferences sharedPreferences = context.getSharedPreferences("Main", Context.MODE_PRIVATE);
        bt_click_status = sharedPreferences.getBoolean("BtnCheck", false);

        if (hashMap != null && bt_click_status == true) {

            if (checkboxclick == true) {
                SharedPreferences sharedPreferences1 = context.getSharedPreferences("ck_itm", Context.MODE_PRIVATE);
                SharedPreferences.Editor editor = sharedPreferences1.edit();
                editor.put
            }
        }
    }
}

RecyclerAdapter（编者）的.java：

GsonBuilder builder = new GsonBuilder();
Gson gson = builder.enableComplexMapKeySerialization().setPrettyPrinting().create();
Type type = new TypeToken < HashMap < String, String >> () {}.getType();
String json = gson.toJson(hashMap, type);
SharedPreferences sharedPreferences1 = context.getSharedPreferences("Ctk", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences1.edit();
editor.putString("chk", json);
editor.commit();

MainActivity.java：

SharedPreferences sharedPreferences1 = getApplicationContext().getSharedPreferences("Ctk", Context.MODE_PRIVATE);
String get = sharedPreferences1.getString("chk", null);
places = new Gson().fromJson(get, new TypeToken < HashMap < String, String >> () {}.getType());
s = places.keySet();
Iterator i = s.iterator();
while (i.hasNext()) {
    Map.Entry entry = (Map.Entry) i.next();
    Log.e("key:" + entry.getKey(), "value:" + entry.getValue());
}

错误:(错误在MainActivity.java中的＆＃34; s = places.entrySet（））

03 - 09 12: 51: 53.658 29260 - 29260 / com.example.jobinsabu.destination E / AndroidRuntime:
FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.jobinsabu.destination.MainActivity$1$1.onClick(MainActivity.java: 173)
at android.view.View.performClick(View.java: 4439)
at android.widget.Button.performClick(Button.java: 148)
at android.view.View$PerformClick.run(View.java: 18395)
at android.os.Handler.handleCallback(Handler.java: 725)
at android.os.Handler.dispatchMessage(Handler.java: 92)
at android.os.Looper.loop(Looper.java: 176)
at android.app.ActivityThread.main(ActivityThread.java: 5302)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java: 511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java: 1102)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 869)
at dalvik.system.NativeStart.main(Native Method)

Answer 1

您可以将其转换为 JSON 字符串，然后将其保存到共享首选项

使用 Gson

    // convert map to JSON String
    GsonBuilder builder = new GsonBuilder();
    Gson gson = builder.enableComplexMapKeySerialization().setPrettyPrinting().create();
    Type type = new TypeToken<HashMap<String,String>(){}.getType();
    String json = gson.toJson(hashMap, type);

并将其转换回 hashmap

String jsonString = "JSON string";
HashMap<String,String> hashMap = new Gson().fromJson(jsonString, new TypeToken<HashMap<String, String>>(){}.getType());

Answer 2

你可以这样做这个Bellow方式

Map<String, String> aMap = new HashMap<String, String>();
aMap.put("key1", "val1");
aMap.put("key2", "val2");
aMap.put("Key3", "val3");

SharedPreferences keyValues = getContext().getSharedPreferences("Your_Shared_Prefs"), Context.MODE_PRIVATE);
SharedPreferences.Editor keyValuesEditor = keyValues.edit();

for (String s : aMap.keySet()) {
    keyValuesEditor.putString(s, aMap.get(s));
}

keyValuesEditor.commit();

android将hashmap保存到SharedPreferences

2 个答案: