Menu
To compare integer values in Java, we can use either the equals() method or == (equals operator). Both are used to compare two values, but the == operator checks reference equality of two integer objects, whereas the equal() method checks the integer values only (primitive and non-primitive).
equals() is a method of Object class. == should be used during reference comparison. == checks if both references points to same location or not. equals() method should be used for content comparison.
In Java, int is a primitive data type while Integer is a Wrapper class. int, being a primitive data type has got less flexibility. We can only store the binary value of an integer in it.
To check two numbers for equality in Java, we can use the Equals() method as well as the == operator. Firstly, let us set Integers. Integer val1 = new Integer(5); Integer val2 = new Integer(5); Now, to check whether they are equal or not, let us use the == operator.
The JVM is caching Integer values. Hence the comparison with == only works for numbers between -128 and 127.
Refer: #Immutable_Objects_.2F_Wrapper_Class_Caching
You can't compare two Integer with a simple == they're objects so most of the time references won't be the same.
There is a trick, with Integer between -128 and 127, references will be the same as autoboxing uses Integer.valueOf() which caches small integers.
If the value p being boxed is true, false, a byte, a char in the range \u0000 to \u007f, or an int or short number between -128 and 127, then let r1 and r2 be the results of any two boxing conversions of p. It is always the case that r1 == r2.
Resources :
On the same topic :
Integer refers to the reference, that is, when comparing references you're comparing if they point to the same object, not value. Hence, the issue you're seeing. The reason it works so well with plain int types is that it unboxes the value contained by the Integer.
May I add that if you're doing what you're doing, why have the if statement to begin with?
mismatch = ( cdiCt != null && cdsCt != null && !cdiCt.equals( cdsCt ) );
The issue is that your two Integer objects are just that, objects. They do not match because you are comparing your two object references, not the values within. Obviously .equals is overridden to provide a value comparison as opposed to an object reference comparison.
"==" always compare the memory location or object references of the values. equals method always compare the values. But equals also indirectly uses the "==" operator to compare the values.
Integer uses Integer cache to store the values from -128 to +127. If == operator is used to check for any values between -128 to 127 then it returns true. for other than these values it returns false .
Refer the link for some additional info
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With