toString and equals are both child of Object Class.

toString method should be override in the class to acieve meaningful output.

@Override
    public String toString(){
        return ; //return String
    }

== operator works properly only on primitive type. eqauls method works for comparing Objects for most part.

 @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }

        if (!(obj instance ClassName)) {
            return false;
        }

        // custom logic here
    }

Workshop 8

@Override
    public String toString(){
        return String.format("%-10s%-15s%-10d%-10.2f%-15s",
                this.firstName, this.lastName, this.grade, this.department);
    }
 @Override
    public boolean equals(Object o){
        if(o == this) return true;
        if(o == null ) return false;
        if(!(o instanceof Student)) return false;
        Student student = (Student) o;
        return student.firstName.equals(firstName) && student.lastName.equals(lastName) &&
                student.grade == grade && student.department.equals(department);
    }