What is the reverse of (ArrayList).toString for a Java ArrayList?

问题

I am using the toString method of ArrayList to store ArrayList data into a String. My question is, how do I go the other way? Is there an existing method that will parse the data in the String instance back into an ArrayList?

回答1:

The short answer is "No". There is no simple way to re-import an Object from a String, since certain type information is lost in the toString() serialization.

However, for specific formats, and specific (known) types, you should be able to write code to parse a String manually:

// Takes Strings like "[a, b, c]"
public List parse(String s) {
  List output = new ArrayList();
  String listString = s.substring(1, s.length() - 1); // chop off brackets
  for (String token : new StringTokenizer(listString, ",")) {
    output.add(token.trim());
  }
  return output;
}

Reconstituting objects from their serialized form is generally called deserialization

回答2:

Here's a similar question:

Reverse (parse the output) of Arrays.toString(int[])

It depends on what you're storing in the ArrayList, and whether or not those objects are easily reconstructed from their String representations.

回答3:

I would recommend using some standard format with a library for it instead.

JSON is probably the closest syntactically.

Alternatively some XML or serialization based solution could work too. It all depends on your needs of course.

回答4:

What does the ArrayList consist of? As others said, it may be impossible in certain cases, but quite possible and guaranteed to work if:

• each string representation of element of the array can be identified unambiguously (as it can be for example if the ArrayList consists of Integers)

• there is a way to create an object of original type from its String representation. I find it most elegant to do this using a static method fromString

Of course, this mimics the whole (de)serialization framework.

回答5:

Apache Commons ftw.

Arrays.asList(StringUtils.split(StringUtils.substringBetween("[1, 2, 3]", "[", "]"), ", "))

来源：https://stackoverflow.com/questions/1518528/what-is-the-reverse-of-arraylist-tostring-for-a-java-arraylist