如何将 arrayList.toString() 转换为实际的 arraylist [英] How to convert an arrayList.toString() into an actual arraylist

问题描述

在我的软件中，由于SQLite 中没有Array 数据类型，我将ArrayList 保存为String.现在我需要使用我的数组并希望将其转换回 ArrayList.我该怎么做?

In my software, since there is no Array data type in SQLite, I saved my ArrayList as a String. Now I need to use my array and want to convert it back to an ArrayList. How can I do it?

这里有一个例子:

ArrayList<String> list = new ArrayList<String>();
list.add("name1");
list.add("name2");
list.add("name3");
list.add("name4");
list.add("name5");
list.add("name6");

String newList = list.toString();
System.out.println(newList);

结果:[name1, name2, name3, name4, name5, name6]

那么现在如何将其转换为 ArrayList?

So now how can I convert this into an ArrayList<String>?

推荐答案

我相信这应该可行:

Arrays.asList(newList.substring(1, newList.length() - 1).replaceAll("\\s", "").split(","));

• 取字符串，去掉第一个和最后一个括号.
• 删除每个空格.
• 以逗号分隔，作为列表收集.

请注意，如果您真的必须为一个项目执行此操作，那么您的代码设计就有问题.但是，如果这只是出于好奇目的，那么此解决方案将起作用.

Note that if really you have to do this for a project, then there is something wrong in your code design. However, if this is just for curiosity purpose then this solution would work.

经过测试

ArrayList<String> list = new ArrayList<String>();
list.add("name1");
list.add("name2");
list.add("name3");
list.add("name4");
list.add("name5");
list.add("name6");

String newList = list.toString();                
List<String> myList = Arrays.asList(newList.substring(1, newList.length() - 1).replaceAll("\\s", "").split(","));

System.out.println(myList);

会正确编译并打印:

[name1, name2, name3, name4, name5, name6]

<小时>

编辑

根据你的评论，如果你真的希望你的变量是一个 ArrayList 实例，那么你可以将列表传递给 ArrayList 构造函数:

As per your comments, if really you want your variable to be an ArrayList<String> instance then you could pass the list to ArrayList constructor :

ArrayList<String> myList = new ArrayList(Arrays.asList(newList.substring(1, newList.length() - 1).replaceAll("\\s", "").split(",")));

你不能直接转换为 Arrays.asList 使用它自己的内置 java.util.Arrays$ArrayList 类.

You can't cast directly as Arrays.asList use it own builtin java.util.Arrays$ArrayList class.

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