Compare every item to every other item in ArrayList

for (int i = 0; i < list.size(); i++) {
  for (int j = i+1; j < list.size(); j++) {
    // compare list.get(i) and list.get(j)
  }
}

What's the problem with using for loop inside, just like outside?

for (int j = i + 1; j < list.size(); ++j) {
    ...
}

In general, since Java 5, I used iterators only once or twice.

This code helped me get this behaviour: With a list a,b,c, I should get compared ab, ac and bc, but any other pair would be excess / not needed.

import java.util.*;
import static java.lang.System.out;

// rl = rawList; lr = listReversed
ArrayList<String> rl = new ArrayList<String>();
ArrayList<String> lr = new ArrayList<String>();
rl.add("a");
rl.add("b");
rl.add("c");
rl.add("d");
rl.add("e");
rl.add("f");

lr.addAll(rl);
Collections.reverse(lr);

for (String itemA : rl) {
    lr.remove(lr.size()-1);
        for (String itemZ : lr) {
        System.out.println(itemA + itemZ);
    }
}

The loop goes as like in this picture: Triangular comparison visual example

or as this:

   |   f    e    d    c    b   a
   ------------------------------
a  |  af   ae   ad   ac   ab   ·
b  |  bf   be   bd   bc   ·   
c  |  cf   ce   cd   ·      
d  |  df   de   ·         
e  |  ef   ·            
f  |  ·               

total comparisons is a triangular number (n * n-1)/2

In some cases this is the best way because your code may have change something and j=i+1 won't check that.

for (int i = 0; i < list.size(); i++){  
    for (int j = 0; j < list.size(); j++) {
                if(i == j) {
               //to do code here
                    continue;
                }

}

}