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In this article, the editor introduces in detail "what's the difference between Java = = and equals", the content is detailed, the steps are clear, and the details are handled properly. I hope this "Java = what's the difference between equals" article can help you solve your doubts, the following follows the editor's ideas slowly in depth, together to learn new knowledge.

= = is an operator of Java, and there are two ways to compare

For basic data types, the judgment of = = is whether the two boundary values are equal.

Public class DoubleCompareAndEquals {Person person1 = new Person (24, "boy"); Person person2 = new Person (24, "girl"); int c = 10; private void doubleCompare () {int a = 10; int b = 10; System.out.println (a = = b); System.out.println (a = = c); System.out.println (person1.getId () = = person2.getId ());}}

For reference types, = = determines whether the quotes on both sides are equal, that is, whether both objects point to the same memory area

Private void equals () {System.out.println (person1.getName (). Equals (person2.getName ());}

Equals is the parent class of any object in Java, which is the method defined by the Object class. Equals can only compare objects, indicating whether the values of both sides of the reference are equal. Keep in mind here that either = = compares or references are equal, while equals compares values, which need to be distinguished.

Equals for comparison between objects has the following characteristics

Reflexivity: x.equals (x) returns true for any non-null reference (x)

Symmetry: for any non-null references (x) and (y), if x.equals (y) is true, then y.equals (x) is also true

Transitivity: there are three values for any non-null reference value: X, y, and z, and if x.equals (y) returns true,y.equals (z) returns true, then x.equals (z) should also return true.

Consistency: for any non-null reference x and y, if x.equals (y) is equal, then they must always be equal.

Non-null: for any non-null reference value x, x.equals (null) must return false.

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