java arraylist not working in for loop

Question

am new to java and facing problem with arraylist , i do not know whats wrong with my "for loop" am unable to exit it , producing error it end

        ArrayList<String> r2 = new ArrayList<String>();
        for(int i=0; i<= idx.length; i++) {
            ArrayList<String> r = db.Fetch(idx[i],exta); 
            if(r.size() != 0) {  
                for (String s : r) {
                    r2.add(s);
                    Log.d("test","ID "+idx[i]+ " :" + s);
                }
            }
        }

When i run it i get correct values printed on Log.d but the loop not exit it end so help

What is idx? Also, the inner for-loop seems to be correct. — Smutje
– Smutje, Commented Feb 24, 2014 at 14:14
Your error is in the 2nd line. Try following code for(int i=0; i<idx.length; i++). Since the for-loop starts at 0, you can't access an element at location X if the size of the ArrayList. The way your code is build up right now, you'll run into an ArrayOutOfBoundsException... — Mathias G.
– Mathias G., Commented Feb 24, 2014 at 14:16

Blackbelt · Accepted Answer · 2014-02-24 14:16:22Z

2

for(int i=0; i<= idx.length; i++)

the indexes of you ArrayList go from 0 to idx.lenght -1 . Looping on the idx.lenght index will cause an ArrayIndexOutBoundExeception. Change it in

   for(int i=0; i <  idx.length; i++)

answered Feb 24, 2014 at 14:16

Blackbelt

158k31 gold badges308 silver badges310 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Nicolai Krüger · Accepted Answer · 2014-02-24 14:21:30Z

0

ArrayList<String> r2 = new ArrayList<String>();
for(int i=0; i< idx.length; i++)
{
    ArrayList<String> r = db.Fetch(idx[i],exta); 

    if(r.size() != 0) {  
        for (String s : r)
        {
            r2.add(s);
            Log.d("test","ID "+idx[i]+ " :" + s);
        }
    }
}

This should work now. You start i at 0 so when i will be equal to idx.length your array at this position dos not exist.

edited Feb 24, 2014 at 14:21

Nicolai Krüger

4314 silver badges18 bronze badges

answered Feb 24, 2014 at 14:18

murielK

1,0301 gold badge11 silver badges21 bronze badges

Collectives™ on Stack Overflow

java arraylist not working in for loop

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related