CODEWITHSUNDEEP
javacompare
koshish kharel
koshish kharel

Reputation: 347

How to create comparator?

How do I create a Comparator that compare the string and display the integer in reverse order leaving the character at same position. eg input=10,20,100,a,50 output should be 100,50,20,a,10.

class StringLengthComparator implements Comparator<String>{

@Override
 public int compare(String o1, String o2)
 {
    return -o1.compareTo(o2);
 }

Upvotes: 0

Views: 226

Answers (2)

Musaddique
Musaddique

Reputation: 443

You can't define Comparator for a string comparison to Integer because we can not compare alphabet with integer value.

so when you use Comaprator or Collection.sort(list<>) will always sort Integer and sort character string.

List<String> numAlpha=new ArrayList<String>();

        numAlpha.add("2");
        numAlpha.add("8");
        numAlpha.add("7");
        numAlpha.add("b");
        numAlpha.add("6");

        numAlpha.add("y");
        numAlpha.add("test");
        numAlpha.add("alpha");

        Collections.sort(numAlpha);
        System.out.println(numAlpha.toString());

output: [2, 6, 7, 8, alpha, b, test, y]

Upvotes: 0

Eran
Eran

Reputation: 393811

There is no way to define a Comparator that would produce the output you want, since a Comparator must define a consistent ordering, and your requirements don't.

Consider these two inputs :

10,20,100,a,50

10,20,100,a,5

In the first, you want the order to be :

100,50,20,a,10

While in the second you want :

100,20,10,a,5

You can't define a Comparator in which for some inputs "a">"10" while for others "a"<"10".

Upvotes: 2

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