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I want to compare to variables, both of type T extends Number. Now I want to know which of the two variables is greater than the other or equal. Unfortunately I don't know the exact type yet, I only know that it will be a subtype of java.lang.Number. How can I do that?
EDIT: I tried another workaround using TreeSets, which actually worked with natural ordering (of course it works, all subclasses of Number implement Comparable except for AtomicInteger and AtomicLong). Thus I'll lose duplicate values. When using Lists, Collection.sort() will not accept my list due to bound mismatchs. Very unsatisfactory.
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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.
To enable two objects of a generic type parameter to be compared, they must implement the IComparable or IComparable<T>, and/or IEquatable<T> interfaces. Both versions of IComparable define the CompareTo() method and IEquatable<T> defines the Equals() method.
If you need to compare objects of type T for equality/inequality, you can use the IEquatable<T> interface.
This should work for all classes that extend Number, and are Comparable to themselves. By adding the & Comparable you allow to remove all the type checks and provides runtime type checks and error throwing for free when compared to Sarmun answer.
class NumberComparator<T extends Number & Comparable> implements Comparator<T> { public int compare( T a, T b ) throws ClassCastException { return a.compareTo( b ); } } If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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