Determining an arrays value depending on another array

Question

I'm currently working on one of my assignments, and am looking for some help with the logic for one of my functions.

First off I have a array of numbers to be categorized, then a number interval, this number determines in which position each of the numbers being plotted goes into array2.

ie.

int interval = 2;

for(int i = 0; i < array1.length; i++) {
    if((array1[i] > 0) && (array1[i] < interval)) {
        array2[0]++;
    }
}

However, the number from array1 is 3. I would then need another if statement like so:

...
}else if((array1[i] > 2) && (array1[i] < interval * 2)) {
    array2[1]++;
}else if((array1[i] > 

As you can start to see the problem with this is that I would need to continue for an infinite range of numbers. So my question is what is an easier way of achieving this goal? Or is there already a library which I can utilize to do so?

I'm sorry if I didn't make this clear enough, also I would prefer if code wasn't given to me. I would appreciate if someone would be able to tell me a more effective way about going about this, thanks in advance!

EDIT:

Assuming that the interval is set to 2, and the numbers from array1 are between 0 and 10, I would need to create a code that would do such:

2 < numFromArray1 > 0 == array2[0]++
4 < numFromArray1 > 2 == array2[1]++
6 < numFromArray1 > 4 == array2[2]++
8 < numFromArray1 > 6 == array2[3]++
10 < numFromArray1 > 8 == array2[4]++

However, the numbers from array1 can be positive or negative, whole or decimal.

Answer 1

Use a nested loop. Obviously it's not infinitely many possibilities for interval because array2 has a fixed size. So if you loop through all the cells in array2, and then do some math to figure out what your conditions need to be... I won't give complete code (you asked me not to, but it would look something like:

for ( ... ) {
    for ( ... ) { 
        if (array1[i] > /* do some math here */ && ... ) {
            array2[/* figure out what this should be too */]++;
        }
    }
 }

Hopefully you can figure it out from this.

By the way, if you aren't required to use an array for array2, consider learning about LinkedList<?>for a data structure that can grow in size as you need it to.

http://docs.oracle.com/javase/1.4.2/docs/api/java/util/LinkedList.html

http://www.dreamincode.net/forums/topic/143089-linked-list-tutorial/

Answer 2

Assuming I understood the question correct, and the interval would be 3, than occurrences of 0, 1 and 2 would increase array2[0], occurences of 3, 4 and 5 would increase array2[1] and so on, this would be a solution:

EDIT sorry, you did not want to see code. I can repost it, if you want. Think about a real easy way to determine which category a number will be in. I'll try to give a hint.

Interval = 3;
0,1,2 -> category 0
3,4,5 -> category 1
6,7,8 -> category 2

Once you know the category, it is easy to increment the desired number in array2.

It would look something like that:

for(int i = 0; i < array1.length; i++) {
    int category = // determine category here
    // increase correct position of array2
}

After some dicussion, here is my code:

for(int i = 0; i < array1.length; i++) {
    int category = array1[i] / interval;
    array2[category]++;
}

My solution won't work for negative numbers. Also it is not specified how to handle them