Looping through an array to compare object properties without duplicating

I am trying to move objects around a grid and counting the fights(when they touch) but every time I get one interaction they it counts it twice. I understand why, but cannot think of a way around it.

code:

        // Move all the objects
        for(int i = 0; i < objectArray.length; i++) {
            objectArray[i].move();
        }

        // Check to see if any of the objectsare touching
        for(int i = 0; i < objectArray.length; i++) {

            for(int j = 0; j < objectArray.length; j++) {

                if(objectArray[i] != objectArray[j]) {

                    if(objectArray[i].getX() == objectArray[j].getX() && objectArray[i].getY() == objectArray[j].getY()) {


                            System.out.println("FIGHT");
                            System.out.println("There is a fight between " + objectArray[i].getName() + " and " + objectArray[j].getName() + "." );

                            fights++;

                        }
                    }
                }
            }
        }

you're going through the entire list, and for each element in the list you... go through the entire list. again.

Don't do that - if you want each item in the list to 'meet' each other item in the list, then, well, think of that first loop: The first 'fighter' will, in your loop, meet itself (j = 0), and then meet all other fighters. You eliminate the 'meet yourself' option with an if (the first if).

Then the next fighter (i = 1) will start from the beginning again: It will meet the first fighter (j = 0), repeating the fight we already saw, then meet itself, then meet the rest of the field.

The solution is to start the inner loop not at '0', but at the next fighter after yourself: That second fighter should first meet the third (and skip the first, and itself). So, int j = i + 1, not int j = 0, that's all you need. You can then also eliminate the 'do not fight yourself' if line entirely, as that cannot happen now.

You could make loop properties, probably not the best answer but it will work to make sure you don't compare the same two objects in the array.

code:
// Loop properties
String lastFightObejectOne = "", lastFightObjectTwo = "";

        // Move all the objects
        for(int i = 0; i < objectArray.length; i++) {
            objectArray[i].move();
        }

        // Check to see if any of the objects are touching
        for(int i = 0; i < objectArray.length; i++) {

            for(int j = i + 1; j < objectArray.length; j++) {

                if(objectArray[i] != objectArray[j]) {

                    if(objectArray[i].getX() == objectArray[j].getX() && objectArray[i].getY() == objectArray[j].getY()) {

                            if(!lastFightObejectOne.equal(objectArray[i].getName()) && (!lastFightObejectTwo.equal(objectArray[j].getName())) {
                            System.out.println("FIGHT");
                            System.out.println("There is a fight between " + objectArray[i].getName() + " and " + objectArray[j].getName() + "." );

                            lastFightObjectOne = objectArray[i].getName();
                            lastFightObectTwo = objectArray[j].getName();

                            fights++;
                            }
                        }
                    }
                }
            }
        }