Java 9 Programming By Example

Implementing equals and hashCode

Implementing these methods is fairly simple. As this is a very common task, the IDEs support the generation of these methods. These methods are tied together so much that the menu items in the IDEs are not separate; they offer you to generate these methods at once.

Asking the IDE to generate the equals method will result in something like the following code:

@Override  public boolean equals(Object o) {      if (this == o) return true;      if (o == null || getClass() != o.getClass()) return false;      MyObjectJava7 that = (MyObjectJava7) o;      return Objects.equals(field1, that.field1) &&              Objects.equals(field2, that.field2) &&              Objects.equals(field3, that.field3);  }

For this sample, we have three Object fields named ...