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Simple array equality question (hopefully!)

1 reply on 1 page. Most recent reply: Oct 8, 2004 5:17 PM by Kishori Sharan

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Guido

Posts: 38
Nickname: kiethb
Registered: May, 2002

Simple array equality question (hopefully!)

Posted: Oct 8, 2004 6:54 AM

can someone tell me why the following doesn't work?

public class AryTest{
 
	static String[] str = {"Java ","is ", "great!"};
	static String[] str2 = {"Java ","is ","great!"};
 
        public static void main(String[] args){
 
        if(str.equals(str2)){
	     System.out.println("they are equal!");
	}
	else{
		System.out.println("they are not equal!");
		}

I know that if I import the Arrays class and do a test like:

if(Arrays.equals(str,str2))

that will work, I just need to know why the other doesn't work and/or why if its not testing anything useful that it doesn't throw a compile error.

thank you

Kishori Sharan

Posts: 211
Nickname: kishori
Registered: Feb, 2002

Re: Simple array equality question (hopefully!)

Posted: Oct 8, 2004 5:17 PM

An array in Java is an object. Here, str and str2 are two different objects. By default, equals() method compares the references to two objects. It returns true only if two objects being compared are same. That is, o1.equals(o2) is same as o1 == o2 unless the class of o1 overrides the equals() method. Since array object's class is built-in class types, we cannot override array class equals() method. So, you will have to accept the default behaviour. That is, str.euals(str2) is same as saying str == str2. And, you know that str is certainly not same as str2.

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