Java的ArrayList的转换为字符串，返回ArrayList的？ [英] Java convert ArrayList to string and back to ArrayList?

问题描述

我想保存一个ArrayList共享preferences所以我需要把它变成一个字符串回来了，这是我在做什么：

  //保存到共享preferences
共享preferences共享preF = this.get preferences（Activity.MODE_PRIVATE）;
共享preferences.Editor编辑= this.get preferences（Activity.MODE_PRIVATE）.edit（）;
editor.putString（myAppsArr，myAppsArr.toString（））;
editor.commit（）;
 

我可以用检索字符串arrayString =共享pref.getString（yourKey，NULL）; ，但我不知道如何转换arrayString回到一个ArrayList。如何能做到？

---

我的阵列看起来像：

  [项目1，项目2，项目3]
 

解决方案

您有两个选择：

1. 手动解析字符串并重新创建ArrayList中。这将是pretty乏味。



2. 使用一个JSON库像谷歌的 GSON 库存储和检索对象作为JSON字符串。这是一个轻量级的库，以及重视和欢迎。这将是你的情况需要最小的工作的理想解决方案。如，

     //如何储存JSON字符串
   GSON GSON =新GSON（）;
   //这可以是任何对象。不必成为一个ArrayList。
   JSON字符串= gson.toJson（myAppsArr）;//如何找回您的Java对象从字符串返回
   GSON GSON =新GSON（）;
   数据对象的obj = gson.fromJson（arrayString，ArrayList.class）;
    

I wanted to save an ArrayList to SharedPreferences so I need to turn it into a string and back, this is what I am doing:

// Save to shared preferences
SharedPreferences sharedPref = this.getPreferences(Activity.MODE_PRIVATE);
SharedPreferences.Editor editor = this.getPreferences(Activity.MODE_PRIVATE).edit();
editor.putString("myAppsArr", myAppsArr.toString());
editor.commit();

I can retrieve it with String arrayString = sharedPref.getString("yourKey", null); but I don't know how to convert arrayString back into an ArrayList. How can it be done?

---

My array looks something like:

[item1,item2,item3]

解决方案

You have 2 choices :

1. Manually parse the string and recreate the arraylist. This would be pretty tedious.

2. Use a JSON library like Google's Gson library to store and retrieve objects as JSON strings. This is a lightweight library, well regarded and popular. It would be an ideal solution in your case with minimal work required. e.g.,

   // How to store JSON string
   Gson gson = new Gson();
   // This can be any object. Does not have to be an arraylist.
   String json = gson.toJson(myAppsArr);
   
   // How to retrieve your Java object back from the string
   Gson gson = new Gson();
   DataObject obj = gson.fromJson(arrayString, ArrayList.class);
   

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