在没有集合的情况下在ArrayList中查找最小整数

Question

I'm trying to find the smallest integer in an ArrayList just by using two simple for loops. I tried originally with one for loop, but it wasn't updating correctly. I haven't learned collections yet, so this should be done without using any collections code.

This is what I have:

public static void printInOrder(ArrayList<Integer> data){

 int minIndex = 0 ;
 for(int i = 0; i < data.size(); i++){
   minIndex = i;
   for(int j = i + 1; j < data.size() - 1; j++){
     if(data.get(j) < data.get(minIndex)){
       minIndex = j;}

   }
   System.out.println(data.get(minIndex) + " ");
 }
}//printInOrder

My minimum always seems to be the last value in the list, so I tried printing the data.get(minIndex) in the first for loop to see what happens, and it seems to update it different values, and then finally, the last value. I have no idea why this is happening.

This is what it's printing for example:

Original list: [47, 19, 46, 42, 15, 26, 36, 27, 13, 15, 1, 40, 34, 14, 6, 34, 28, 12, 15, 13] Print the minimum: 1 1 1 1 1 1 1 1 1 1 1 6 6 6 6 12 12 12 15 13

Answer 1

You can do this quick solution if you want to avoid using Collections.

public static void printInOrder(ArrayList<Integer> data){

    Integer[] array = (Integer[]) data.toArray();
    Arrays.sort(array);
    System.out.println(array[0]);

}

The smallest integer would always be at index 0 in this case.

Or, if you do want to go through the whole ArrayList using a loop, I'd suggest you store the actual value in a variable instead of the index. Doing so, you get:

public static void printInOrder(ArrayList<Integer> data){

    int minInteger = data.get(0);
    for(int i = 1; i < data.size(); i++){
        if(data.get(i) < minInteger) minInteger= data.get(i);
    }
    System.out.println(minInteger);

}

Answer 2

You're not supposed to do sorting to find the minimum

Here's the code

public static void Min(int arr[])
{
   int min = arr[0];
    int i=0;
while(i<arr.length)
 {
        if (arr[i] < min) {
            min=arr[i];
        }
    }
    return min;
}

Answer 3

Untested:

public static int calculateMinIndex(final ArrayList<Integer> data) {
    int minIndex = 0;
    for(int i = 0; i < data.size() - 1; i++) {
        if(data.get(i) > data.get(i+1)) {
            minIndex = i+1;
        }
    }
    return minIndex;
}