How do you find the smallest value of an ArrayList?

Question

I have an array list called children that has objects that move around certain whole value distances in the GUI and I need to find the smallest of these values and print it to the console.

I'm pretty sure this calls for a for loop right? I just don't know how to structure it correctly to make sure it looks at the values within the "children" ArrayList. Or is there some built in functionality within Eclipse to calculate the smallest value of an array list?

Possible duplicate of [Finding smallest value in an array most efficiently](http://stackoverflow.com/questions/1042507/finding-smallest-value-in-an-array-most-efficiently) — Charles C., Mar 24 '16 at 22:27
With Java 8 you can just do `yourlist.stream().min(someComparator)` — tobias_k, Mar 24 '16 at 22:29
What is the type of the elements within the list? Numbers, or some other type? If another type, by what criterion do you want to compare those? — tobias_k, Mar 25 '16 at 10:24

TheMirrox · Answer 1 · 2016-03-24T22:48:10.623

11

The Collection class has static methods for finding the smallest or the largest element in a Collection. For example:

 System.out.println("max: " + Collections.max(list));
 System.out.println("min: " + Collections.min(list));

edited Mar 24 '16 at 22:48

answered Mar 24 '16 at 22:42

TheMirrox

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score 8 · Answer 2 · answered Mar 24 '16 at 22:32

8

If you have and array of positive integer values you can find the smallest one with the following logic:

int [] numbers = {10, 20, 30, 40, 50};
int smallest = numbers[0];
for(int x : numbers ){
   if (x < smallest) {
      smallest = x;
   }
}
System.out.println(smallest);

answered Mar 24 '16 at 22:32

dlicheva

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My array list is children and there are 5 children that move a random distance in the gui. How would you structure that so that it knows to look at the "children" array list? – Austin Brown Mar 24 '16 at 22:35

Laurel · Answer 3 · 2016-03-24T22:54:48.693

0

Something like:

double smallest= children.get(0);
for(double d: children){
    if(smallest > d) smallest=d;

}

edited Mar 24 '16 at 22:54

answered Mar 24 '16 at 22:29

Laurel

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I tried this and got an error message saying "The operator > is undefined for the argument types" – Austin Brown Mar 24 '16 at 22:39
@AustinBrown I've just run it on Ideone, is children an `ArrayList`? – Laurel Mar 24 '16 at 22:54

score 0 · Answer 4 · answered Mar 24 '16 at 22:36

0

You can sort the arraylist using Comparators http://beginnersbook.com/2013/12/java-arraylist-of-object-sort-example-comparable-and-comparator/

Once it is sorted, pick the first value, it will be smallest one

answered Mar 24 '16 at 22:36

Ambidextrous

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score 0 · Answer 5 · answered Mar 24 '16 at 22:47

You're right, you must use loops. You need to take a value out of the list an compare it to all other values. If there is no smaller one, it's the smallest. If there is, you need do check the next one. Java code could soething like this:

numberLoop: for(int number: children){
    for(int numberToCompare: children){
        if(numberToCompare < number)numberLoop.continue;
    }
    System.out.println(number);
    break;
}

PS: It's not Eclipse that's providing the methods. It's basically just a programm to edit text (like Word). The methods are provided by the java API

score 0 · Answer 6 · answered Apr 11 '17 at 07:44

Using Java 8 Streams ,

Let arr is a array of integers,

int[] arr = new int[]{54,234,1,45,14,54};    
int small = Arrays.stream(arr).reduce((x, y) -> x < y ? x : y).getAsInt();
int large = Arrays.stream(arr).reduce((x, y) -> x > y ? x : y).getAsInt();
System.out.println(small);
System.out.println(large);

score 0 · Answer 7 · answered Dec 23 '20 at 18:05

You can find the smallest value of an ArrayList using the following ways in JAVA ARRAY List: way 1. Find the smallest value of an ArrayList using the Collection class.

you are available with a collection class named min.
This method returns the minimum element/value of the specified collection according to the natural ordering of the elements.
static <T extends Object & Comparable<? super T> min(Collection<? extends T> c)

Example

package com.javacodeexamples.collections.arraylist;
import java.util.ArrayList;
import java.util.Collections;
public class FindMinValueArrayListExample {
 
    public static void main(String[] args) {
        
        /*
         * ArrayList containing student marks
         */
        ArrayList<Integer> aListMarks = new ArrayList<Integer>();
        
        //add elements to ArrayList
        aListMarks.add(53);
        aListMarks.add(67);
        aListMarks.add(89);
        aListMarks.add(43);
        aListMarks.add(87);
        aListMarks.add(71);
        aListMarks.add(63);
        aListMarks.add(45);
        aListMarks.add(69);
        aListMarks.add(53);
        
        /*
         * To find minimum value in ArrayList, use
         * min method of Collections class.
         */
        
        System.out.println( "ArrayList Min Value: " + Collections.min(aListMarks) );
        
             
    }
}

The output is :

ArrayList Min Value: 43

Way 2: Find the smallest value of an ArrayList using the for loop.

You can make use of for loop instead of collections.

Example

package com.javacodeexamples.collections.arraylist;
 
import java.util.ArrayList;
 
public class FindMinValueArrayListExample {
 
    public static void main(String[] args) {
        
        /*
         * ArrayList containing student marks
         */
        ArrayList<Integer> aListMarks = new ArrayList<Integer>();
        
        //add elements to ArrayList
        aListMarks.add(53);
        aListMarks.add(67);
        aListMarks.add(89);
        aListMarks.add(43);
        aListMarks.add(87);
        aListMarks.add(71);
        aListMarks.add(63);
        aListMarks.add(45);
        aListMarks.add(69);
        aListMarks.add(53);
        
        //declare min and max value as the first element of the list
        int min = aListMarks.get(0);
                   
        //declare min and max elements index as 0 (i.e. first element)
        int minIndex = 0;
        
        //Iterate through ArrayList
        for(int i = 1; i < aListMarks.size(); i++ ){
    
             /*
              * If current value is less than min value, it 
              * is new minimum value
              */
            
            if( aListMarks.get(i) < min ){
                min = aListMarks.get(i);
                minIndex = i;
            }
                    
        System.out.println("ArrayList Min Value is: " 
                            + min 
                            + ", Found at index: "
                            + minIndex
                );
 
       }
}

The result is

ArrayList Min Value is: 43, Found at index: 3

While this answers the question, it does so in a verbose way, and the highest-voted answer essentially says 'use Collections.min' which is what your answer says but in so many more words. — AlBlue, Dec 23 '20 at 19:39

score 0 · Answer 8 · answered Dec 24 '20 at 06:52

For a recursive solution

public static void main(String[] args) {
        int arr[] = {1, 4, 45, 6, -50, 10, 2};
        System.out.println("Minimum value = " + minValue(arr,arr.length));
    }
    
    static int minValue (int arr[], int n){
        if(n == 1){
            return arr[0];
        }
        return Math.min(arr[n-1], minValue(arr,n-1));
    }

score 0 · Answer 9 · edited Nov 02 '21 at 13:44

0

This worked for me!

public void minValue() {
    // given
    List<Integer> listOfIntegers = Arrays.asList(1, 2, 3, 4, 56, 7, 89, 10);
    Integer expectedResult = 1;

    // then
    Integer min= listOfIntegers
      .stream()
      .mapToInt(v -> v)
      .min().orElseThrow(NoSuchElementException::new);

    assertEquals("Should be 1", expectedResult, min);
}

edited Nov 02 '21 at 13:44

João Dias

16,277
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answered Nov 02 '21 at 09:34

S.Iliev

48
1
6

How do you find the smallest value of an ArrayList?

9 Answers9

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