[JAVA] please tell me this for loop

[uperkurk]

Hey guys, I have an

ArrayList<String> al = ArrayList<String>();

and I have a textbox, the textbox allows a user to enter a word and that word will be added into the ArrayList.

When I print the list out it looks like this

[Cat, Dog, Mouse]

can you please write out the for loop that I need in order to change the ArrayList into a string? I want the output to look like this

Cat Dog Mouse

Please don't say go read this or read that, I've googled for loops but I can't find one that will do what I want.

Thanks.

 

[jedishrfu]

Check out this example:

http://www.java-examples.com/iterate-through-elements-java-arraylist-using-listiterator-example

add a line for boxtext:

String boxtext = "";

replace the System.out.println lines in the first for loop with:

boxtext=boxtext + itr.next();

There's other ways of doing it with StringBuffers or StringBuilders which are more efficient but hey String is so ingrained...

 

[gabbagabbahey]

The collections-based for loop does almost the same thing, just behind the scenes (it uses and iterator in its implementation), and is a little easier to code:

ArrayList<String> al = new ArrayList<String>();
al.add("cat");
al.add("dog");
al.add("mouse");

for(String str : al) {
    System.out.println(str + " ");
}

For read-only access to your ArrayList, this is the way to go. You will run into problems if you try to remove objects from your ArrayList in such a loop, however (you will get a ConcurrentModificationException), whereas the while loop in jedishrfu's example will have no such problems.

 

[uperkurk]

The collections-based for loop does almost the same thing, just behind the scenes (it uses and iterator in its implementation), and is a little easier to code:

ArrayList<String> al = new ArrayList<String>();
al.add("cat");
al.add("dog");
al.add("mouse");

for(String str : al) {
    System.out.println(str + " ");
}

For read-only access to your ArrayList, this is the way to go. You will run into problems if you try to remove objects from your ArrayList in such a loop, however (you will get a ConcurrentModificationException), whereas the while loop in jedishrfu's example will have no such problems.

Exactly what I was looking for thank you so much! I had the exact same thing but I was using

for(str : al) instead of for(string str : al)

Cheers bro!

 

[jedishrfu]

With respect to the collections based for loop just be aware that it is in java 5 and beyond. Sometimes programmers are maintaining java 1.4 code or earlier and collections based for loops aren't supported.