Modify String objects in a static array

Question

I want to make a for-loop to add a letter to each string object in my list. I'm just not sure how to edit the objects in the list and not the actual list.

for instance, if I wanted to add "ing" to the end of each object in my list..

I feel like it's something simple, but I've been looking through oracle forever and haven't been able to figure it out if anyone can point me in the right direction?

I could use any kind of list really.. just anything that works.

I was thinking something like,

    String[] stringArray = tools.toArray(new String[0]);
            for (int i = 0; i < stringArray.length; i++)
            {
                stringArray[i] = stringArray[i].*part that would modify would go here*
            }

You can't modify Strings, so you need to use some other kind of object or modify list. — TomekK
– TomekK, Commented Sep 25, 2016 at 23:17

donkon · Accepted Answer · 2016-09-25 23:27:23Z

1

You cannot edit a String. They are immutable. However, you can replace the entry in the list.

ArrayList<String> list = new ArrayList<>();
list.add("load");
list.add("pull");

for (int i = 0; i < list.size(); ++i) {
    list.set(i, list.get(i) + "ing");

You updated your question to specify a static array:

stringArray[i] = stringArray[i] + "ing";

The right side of the assignment is performing a String concatenation which can be done with the + operator in Java.

edited Sep 25, 2016 at 23:27

answered Sep 25, 2016 at 23:22

donkon

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1 Comment

Tokazio Over a year ago

I think doing stringArray[i] = stringArray[i] + "ing"; will automatically replace the old reference with the one of the new String created for the concatenation.

Roxy · Accepted Answer · 2016-09-25 23:35:28Z

1

You can use StringBuilder for this purpose.

public static void addIng(String[] arr) {
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < arr.length; i++) {
        sb.setLength(0);
        sb.append(arr[i] + "ing");
        arr[i] = sb.toString();
    }
}

answered Sep 25, 2016 at 23:35

Roxy

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Comments

Barnabus · Accepted Answer · 2016-09-25 23:21:42Z

0

Strings are immutable in java; they can't be modified once created.

Here it seems you have a few options; you can create a method that takes your list and returns a new list, by appending 'ing' to the end of each string in the list.

Alternatively, if you need to keep a reference to the original list, you can loop over the contents of the list (ArrayList?) and pop each string out, create a new string with the appended 'ing', and replace in the list.

answered Sep 25, 2016 at 23:21

Barnabus

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Tokazio · Accepted Answer · 2016-09-25 23:33:44Z

0

Something like

List<String> list = new ArrayList<>();
list.add("testing");
for(String s:list){
    s=s+"ing";
}

answered Sep 25, 2016 at 23:33

Tokazio

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Henry · Accepted Answer · 2016-09-25 23:45:09Z

0

Please take a look below samples.

   //Java 8 code.
   List<String> oldList = Arrays.asList("a", "b");
   List<String> newList = oldList.stream().map(str -> new StringBuilder(str).append("ing").toString()).collect(Collectors.toList());
   System.out.println(oldList); // [a, b]
   System.out.println(newList); // [aing, bing]

   // Java 7 or below.
   List<String> oldList = Arrays.asList("a", "b");
   List<String> newList = new LinkedList<String>();
   for (String str : oldList) {
       newList.add(new StringBuilder(str).append("ing").toString());
   }
   System.out.println(oldList); // [a, b]
   System.out.println(newList); // [aing, bing]

answered Sep 25, 2016 at 23:45

Henry

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