How to compare two Integers in java

Question

I want to compare elements in two list using < > ==

Is it the right way to use intValue()?

List<Integer> a = new ArrayList<Integer>();
a.add(129);

List<Integer> b = new ArrayList<Integer>();
b.add(128);

if(a.get(0).intValue() > b.get(o).intValue()) {
   // something
}

if I also need < > , you mean only change this with <0 and >0 in the right? — user3495562, Apr 16 '14 at 17:27
http://stackoverflow.com/questions/11490425/what-is-intvalue-in-java maybe read that :) And don't use intValue() because you don't need it. — martijnn2008, Apr 16 '14 at 17:29
@user3495562 the compareTo method usually output an int (-1, 0, and 1), you need to modify your if statement accordingly. — , Apr 16 '14 at 17:30
Could YOu explain why java need Integer with int already there? — user3495562, Apr 16 '14 at 17:30
int is a primitive type and breaks the OO logic, while Integer is a pure Java class and can be extended and contains more methods — , Apr 16 '14 at 17:32

score 9 · Accepted Answer · answered Apr 16 '14 at 17:29

You're making it the right way.

As stated in the comments, you could also you compareTo(). An alternative to compareTo() is equals() which won't throw a NullPointerException in the case where the object is null.

Sireesh Yarlagadda · Answer 2 · 2014-04-16T20:59:29.570

Your way is correct. But with a small correction.

1)

a.get(0).intValue() == b.get(0).intValue()

2)

a.get(0).equals(b.get(0))

This is the problem in your code, you have to get(0), instead of get(1). Remember, in java it always start with 0.

Values can be compared using equals() or CompareTo method as well.

import java.util.ArrayList;
import java.util.List;

public class TestClass {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        List<Integer> a= new ArrayList<Integer>();
        a.add(128);

        List<Integer> b = new ArrayList<Integer>();
        b.add(128);

        if(a.get(0).intValue() == b.get(0).intValue()){
            System.out.println("success");
        }else{
            System.out.println("failure");
        }
        if(a.get(0).equals(b.get(0))){
            System.out.println("success");
        }else{
            System.out.println("failure");
        }

    }

}

Maybe use the edit feature? Or the comment feature? This doesnt answer the question. — martijnn2008, Apr 16 '14 at 17:33
I have tried that code in my local, it wont work ideally with get(0) , inorder to compare first. Have you tried. @martijnn2008 — Sireesh Yarlagadda, Apr 16 '14 at 17:38

How to compare two Integers in java

2 Answers2