Convert array of strings into a string in Java

Try the Arrays.toString overloaded methods.

Or else, try this below generic implementation:

public static void main(String... args) throws Exception {

    String[] array = {"ABC", "XYZ", "PQR"};

    System.out.println(new Test().join(array, ", "));
}

public <T> String join(T[] array, String cement) {
    StringBuilder builder = new StringBuilder();

    if(array == null || array.length == 0) {
        return null;
    }

    for (T t : array) {
        builder.append(t).append(cement);
    }

    builder.delete(builder.length() - cement.length(), builder.length());

    return builder.toString();
}

Use Apache commons StringUtils.join(). It takes an Object array as a parameter and calls toString() on each element (if it is not null) to get each elements string representation. Each elements string representation is then joined into one string with a separator in between if one is specified:

String joinedString = StringUtils.join(new Object[]{"a", "b", 1}, "-");
System.out.println(joinedString);

Produces:

a-b-1

You want code which produce string from arrayList,

Iterate through all elements in list and add it to your String result

you can do this in 2 ways: using String as result or StringBuffer/StringBuilder.

Example:

String result = "";
for (String s : list) {
    result += s;
}

...but this isn't good practice because of performance reason. Better is using StringBuffer (threads safe) or StringBuilder which are more appropriate to adding Strings

I like using Google's Guava Joiner for this, e.g.:

Joiner.on(", ").skipNulls().join("Harry", null, "Ron", "Hermione");

would produce the same String as:

new String("Harry, Ron, Hermione");

Either use Arrays.toString() or:

StringBuilder builder = new StringBuilder();
for(String s : arr) {
    builder.append(s);
}
return builder.toString();

You can modify the above depending on what characters, if any, you want in between strings.

You may also see near identical code to the above but using StringBuffer - StringBuilder is a newer class that's not thread-safe, but therefore has better performance in a single thread because it does away with unneeded synchronization. In short, you're better using StringBuilder in 99% of cases.

DON'T use a string and just append to it with += like some of the answers show here. This sends the GC through the roof because you're creating and throwing away as many string objects as you have items in your array. For small arrays you might not really notice the difference, but for large ones it's orders of magnitude slower.