Adding comma separated strings to an ArrayList and vice versa

问题

How to add a comma separated string to an ArrayList? My string "returnedItems" could hold 1 or 20 items which I'd like to add to my ArrayList "selItemArrayList".

After the ArrayList has been populated, I'd like to later iterate through it and format the items into a comma separated string with no spaces between the items.

回答1:

String returnedItems = "a,b,c";
List<String> sellItems = Arrays.asList(returnedItems.split(","));

Now iterate over the list and append each item to a StringBuilder:

StringBuilder sb = new StringBuilder();
for(String item: sellItems){
    if(sb.length() > 0){
        sb.append(',');
    }
    sb.append(item);
}
String result = sb.toString();

回答2:

One-liners are always popular:

Collections.addAll(arrayList, input.split(","));

回答3:

split and asList do the trick:

String [] strings = returnedItems.split(",");
List<String> list = Arrays.asList(strings);

回答4:

Simple one-liner:

selItemArrayList.addAll(Arrays.asList(returnedItems.split("\\s*,\\s*")));

Of course it will be more complex if you have entries with commas in them.

回答5:

This can help:

for (String s : returnedItems.split(",")) {
    selItemArrayList.add(s.trim());
}

//Shorter and sweeter
String [] strings = returnedItems.split(",");
selItemArrayList = Arrays.asList(strings);

//The reverse....

StringBuilder sb = new StringBuilder();
Iterator<String> iter = selItemArrayList.iterator();
while (iter.hasNext()) {
    if (sb.length() > 0) 
        sb.append(",");
    sb.append(iter.next());
}

returnedItems = sb.toString();

回答6:

If the strings themselves can have commas in them, things get more complicated. Rather than rolling your own, consider using one of the many open-source CSV parsers. While they are designed to read in files, at least OpenCSV will also parse an individual string you hand it.

Commons CSV
OpenCSV
Super CSV
OsterMiller CSV

回答7:

String csv = "Apple, Google, Samsung";

step one : converting comma separate String to array of String

String[] elements = csv.split(",");

step two : convert String array to list of String

 List<String> fixedLenghtList = Arrays.asList(elements);

step three : copy fixed list to an ArrayList ArrayList listOfString = new ArrayList(fixedLenghtList);

System.out.println("list from comma separated String : " + listOfString);

System.out.println("size of ArrayList : " + listOfString.size()); Output :

list of comma separated String : [Apple, Google, Samsung]


size of ArrayList : 3

回答8:

If the individual items aren't quoted then:

 QString str = "a,,b,c";

 QStringList list1 = str.split(",");
 // list1: [ "a", "", "b", "c" ]

If the items are quoted I'd add "[]" characters and use a JSON parser.

回答9:

You could use the split() method on String to convert the String to an array that you could loop through.

Although you might be able to skip the looping and parsing with a regular expression to remove the spaces using replaceAll() on a String.

回答10:

String list = "one, two, three, four";
String[] items = list.split("\\p{Punct}");
List<String> aList = Arrays.asList(items);
System.out.println("aList = " + aList);
StringBuilder formatted = new StringBuilder();

for (int i = 0; i < items.length; i++)
{
    formatted.append(items[i].trim());
    if (i < items.length - 1) formatted.append(',');
}

System.out.println("formatted = " + formatted.toString());

回答11:

import com.google.common.base.*;

Iterable<String> items = Splitter.on(",").omitEmptyStrings()
                                 .split("Mango,Apple,Guava");

// Join again!
String itemsString = Joiner.join(",").join(items);

来源：https://stackoverflow.com/questions/6096845/adding-comma-separated-strings-to-an-arraylist-and-vice-versa

标签

java

arraylist

csv