【初心者必見】Javaでオリジナルなequals()メソッドの実装

package chap10;

public class Bicycle extends Vehicle {

    int registryNumber;

    public Bicycle(int registryNumber) {
        this.registryNumber = registryNumber;
    }
    
    @Override
    public int hashCode() {
        int hash = 5;
        hash = 47 * hash + this.registryNumber;
        return hash;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final Bicycle other = (Bicycle) obj;
        if (this.registryNumber != other.registryNumber) {
            return false;
        }
        return true;
    }
}

package chap10;

public class Example07 {

    public static void main(String[] args) {

        Bicycle bi1 = new Bicycle(110);
        Bicycle bi2 = new Bicycle(110);
        Bicycle bi3 = new Bicycle(119);

        System.out.println(bi1.equals(bi2));
        System.out.println(bi2.equals(bi3));
    }
}