program to find the largest number in arraylist

Question

Let us imagine that we are having a arraylist in java which contains both intergers and strings value. I would like to loop through the entire arraylist(only taking the integers,ignore string) to find the largest number on the list???i need a program for this task????help me please

possible duplicate http://stackoverflow.com/questions/1484347/java-max-min-value-in-an-array — , Apr 02 '14 at 11:30
Questions asking for code must demonstrate a minimal understanding of the problem being solved. — Jonesopolis, Apr 02 '14 at 12:39

score 2 · Accepted Answer · answered Apr 02 '14 at 11:31

2

Asuming an Object ArrayList, something like this should work:

int biggest = Integer.MIN_VALUE;
for (Object item : list) {
    if(item instanceof Integer && (Integer) item > biggest)
        biggest = item;
}

answered Apr 02 '14 at 11:31

robertoia

2,301
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@MarkoTopolnik True, fixed. – robertoia Apr 02 '14 at 11:32

score 0 · Answer 2 · answered Apr 02 '14 at 11:30

0

Don't keep different data types in a list. Use generics extensively.
you can use instanceOf (ArrayList keeps Integers and Strings) to check type and put the int's seperately and get the largest value.

answered Apr 02 '14 at 11:30

TheLostMind

35,966
12
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104

score 0 · Answer 3 · answered Apr 02 '14 at 11:33

private int getLargestNumber(ArrayList<Objects> list){
    int max = Integer.MIN_VALUE;
    for(int i = 0; i < list.size(); i++){
        Object obj = list.get(i);
        if(obj instanceof Integer && max < (Integer) obj)
                max = (Integer)obj;
    }
    return max;
}

score 0 · Answer 4 · answered Apr 02 '14 at 11:53

When you pass a ArayList object to the below function it will return the bigest Integer from the list ..

 public static Integer getLargerInteger(ArrayList list){
    ArrayList temp=new ArrayList<Integer>();
    for (Object object : list) {
        if(object instanceof Integer){
            temp.add(object);
        }
    }
    return Collections.max(temp);
}

score 0 · Answer 5 · answered Apr 02 '14 at 12:37

You can try the below approach using Comparator Interface rather then looping through all the elements.

    List arr = new ArrayList();
    arr.add(2);
    arr.add(5);
    arr.add(10);
    arr.add(20);
    arr.add("s1");
    arr.add("s2");
    arr.add("s3");

    Collections.sort(arr, new Comparator<Object>() {

        @Override
        public int compare(Object o1, Object o2) {

            if(o1 instanceof Integer && o2 instanceof Integer){
                Integer ob1 = (Integer) o1;
                Integer ob2 = (Integer) o2;
                return ob2.compareTo(ob1);
            }else{
                return -1;
            }
        }

    });
    System.out.println(arr.get(0));

program to find the largest number in arraylist

5 Answers5