Home > Java > javaTutorial > What does equals mean in java

What does equals mean in java

下次还敢
Release: 2024-05-09 06:33:19
Original
433 people have browsed it

In Java, the equals() method determines the equality of objects by comparing the contents of the objects, rather than the references: Default implementation: Compares whether the objects are null or whether the memory addresses are equal. Overriding methods: Compare properties to determine logical equality. Complies with reflectivity, transitivity, and consistency specifications.

What does equals mean in java

Meaning of equals in Java

In Java, equals() method is used to compare two objects of equality. It determines whether two objects are logically equal without comparing their memory references.

Detailed explanation:

  • Comparison logical equality: The equals() method compares the contents or status of two objects, rather than their memory addresses. It essentially determines whether they represent the same entity.
  • Default implementation: The default equals() method of a class in Java checks whether the object is null, and returns true if both are null. Otherwise, it compares their memory addresses and returns true if they are equal, false otherwise.
  • Override the equals() method: In order to correctly compare the equality of custom objects, you need to override the equals() method of the Object class. This overriding method should:

    • Compare the properties of two objects to determine whether they are logically equal.
    • If the objects are the same, return true; otherwise, return false.
    • Adhere to the specifications of the equals() method (including reflection and transitivity).
  • Reflectivity, transitivity and consistency: The equals() method should meet the following principles:

    • Reflectivity : The object should be equal to itself (i.e. o.equals(o) is true).
    • Transitiveness: If o.equals(p) is true and p.equals(q) is true, then o.equals(q) is also true.
    • Consistency: For two non-null objects o and p, consecutive calls to o.equals(p) should always return the same boolean value.

Importance:

equals() method is crucial in Java because:

  • It is used in data structures such as sets to compare and filter elements based on equality.
  • It allows developers to define custom equality rules to suit the needs of a specific application.
  • It helps ensure that objects are compared consistently across applications.

The above is the detailed content of What does equals mean in java. For more information, please follow other related articles on the PHP Chinese website!

source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template