importance of hashcode and equals in java code example

Example 1: How to compare lists of custom classes without defining equals() and hashCode()?

lists equal

Example 2: hashcode comparison in java

public class EqualsAndHashCodeExample {

    public static void main(String... equalsExplanation) {
        System.out.println(new Simpson("Homer", 35, 120)
                 .equals(new Simpson("Homer",35,120)));
        
        System.out.println(new Simpson("Bart", 10, 120)
                 .equals(new Simpson("El Barto", 10, 45)));
        
        System.out.println(new Simpson("Lisa", 54, 60)
                 .equals(new Object()));
    }
	
    static class Simpson {

        private String name;
        private int age;
        private int weight;

        public Simpson(String name, int age, int weight) {
            this.name = name;
            this.age = age;
            this.weight = weight;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }
            Simpson simpson = (Simpson) o;
            return age == simpson.age &&
                    weight == simpson.weight &&
                    name.equals(simpson.name);
        }
    }

}