Not sure why I am getting this error,,

Question about the task

Resolved

THIS IS THE ERROR I am getting.. method addAll in class java.util.Collections cannot be applied to given types; required: java.util.Collection<? super Line 27 is the error message..

1. Create a Human class with String name, boolean sex, int age, and ArrayList<Human> children fields.
2. Create and populate objects so that we end up with: two grandfathers, two grandmothers, one father, one mother, and three children.
3. Display all the Human objects (Hint: use the Human class's toString() method).

Requirements:

The program should display text on the screen.
The Human class must have four fields.
The Human class must have one method.
The Solution class must have one method.
The program should create objects and fill them with data to get two grandfathers, two grandmothers, one father, one mother, and three children. Then it should display all the Human objects on the screen.

package com.codegym.task.task08.task0824; /* Make a family */ import java.util.*; public class Solution { public static void main(String[] args) { //write your code here ArrayList<Human> childrenYounger = new ArrayList<>(); ArrayList<Human> childrenMother = new ArrayList<>(); ArrayList<Human> childrenFather = new ArrayList<>(); Human grandfather1 = new Human("Bob", true, 67, childrenFather); Human grandfather2 = new Human("Tom", true,77, childrenMother ); Human grandmother1 = new Human("Susan", false,66, childrenFather); Human grandmother2 = new Human("Mary", false, 56, childrenMother); Human father = new Human("Bill", true, 40, childrenYounger); Human mother = new Human("Balbina", false,38, childrenYounger); Human child1 = new Human("Cathlyn", false, 12, new ArrayList<>()); Human child2 = new Human("Ben", true,13, new ArrayList<>()); Human child3 = new Human("Maja", false, 14, new ArrayList<>()); Collections.addAll(childrenYounger,child1,child2,child3); Collections.addAll(childrenFather,childrenMother,father,mother); System.out.println(grandfather1.toString()); System.out.println(grandfather2.toString()); System.out.println(grandmother1.toString()); System.out.println(grandmother2.toString()); System.out.println(father.toString()); System.out.println(mother.toString()); System.out.println(child1.toString()); System.out.println(child2.toString()); System.out.println(child3.toString()); } public static class Human { //write your code here String name; boolean sex; int age; ArrayList <Human> children = new ArrayList<>(); public Human(String name, boolean sex, int age, ArrayList<Human> children){ this.name = name; this.sex = sex; this.age = age; this.children = children; } public String toString() { String text = ""; text += "Name: " + this.name; text += ", sex: " + (this.sex ? "male" : "female"); text += ", age: " + this.age; int childCount = this.children.size(); if (childCount > 0) { text += ", children: " + this.children.get(0).name; for (int i = 1; i < childCount; i++) { Human child = this.children.get(i); text += ", " + child.name; }//end of for loop }//end of if return text; }//end of toString }// end of Human }//end of main

Comments (4)

Popular
New
Old

You must be signed in to leave a comment

Anood

Level 0

12 November 2019, 20:36

Create a class with empty constructor. Name of a class : Faculty Fields : ArrayList designation Implement a method named as addDesignation(String desig) to add four types of designations in the array list. The four types of designations are lecturer, assistant, associate and professor. Implement a method called listAssistant() to display only assistant from the collection (array list). Hints: Use for loop to access every object in the collection. Use if condition inside the for loop to check the taken object is assistant or not. Implement a method called listAll() to display all designations from the collection. Hints: Use for loop to step out and display all the objects from the collection

Raluca Rosu

Level 24 , Timisoara, Romania

9 August 2019, 05:49

You need to have 2 constructors. One for children and another one for parents

Hossein Shams

Level 26 , Atlanta, United States

9 August 2019, 04:23

That's because you're trying to add an ArrayList to another ArrayList with not a type of ArrayList. Try to add 'mother' to 'childrenMother' in a separate line. Also in lines 22-24, since they don't have any children, you can pass 'null' as the last argument to children (for saving some resources)

Steve

Level 9 , Denver, United States

16 August 2019, 17:50

Thanks Seyyed, that works!!