Output seems to be correct, but I'm not sure where the error is?

Question about the task

Cat relations

Java Syntax, Level 6, Lesson 11

Resolved

Example output:

The cat's name is Grandfather Tiger, no mother, no father
The cat's name is Grandmother Puss, no mother, no father
The cat's name is Father Oscar, no mother, Grandfather Tiger is the father
The cat's name is Mother Missy, Grandmother Puss is the mother, no father
The cat's name is Son Simba, Mother Missy is the mother, Father Oscar is the father
The cat's name is Daughter Coco, Mother Missy is the mother, Father Oscar is the father

My output:

The cat's name is Grandfather Tiger, no mother, no father
The cat's name is Grandmother Puss, no mother, no father
The cat's name is Father Oscar, no mother, Grandfather Tiger is the father
The cat's name is Mother Missy, Grandmother Puss is the mother, no father
The cat's name is Son Simba, Mother Missy is the mother, Father Oscar is the father
The cat's name is Daughter Coco, Mother Missy is the mother, Father Oscar is the father

Also bonus points for helping me understand why my while loop doesn't satisfy the first condition. Thanks!

Task: Each cat has a name and a mother.
Create a class that describes this situation.
Create two objects: a daughter cat and a mother.
Display them on the screen.

New task: Each cat has a name, a father, and a mother.
Edit Cat so that it reflects these relationships.
Create 6 objects: grandfather (the father's father), grandmother (the mother's mother), father, mother, son, daughter.
Display them all in the following order: grandfather, grandmother, father, mother, son, daughter.

Example input:
Grandfather Tiger Grandmother Puss Father Oscar Mother Missy Son Simba Daughter Coco

Example output:
The cat's name is Grandfather Tiger, no mother, no father The cat's name is Grandmother Puss, no mother, no father The cat's name is Father Oscar, no mother, Grandfather Tiger is the father The cat's name is Mother Missy, Grandmother Puss is the mother, no father The cat's name is Son Simba, Mother Missy is the mother, Father Oscar is the father The cat's name is Daughter Coco, Mother Missy is the mother, Father Oscar is the father

Requirements:

The program should read in the names of 6 cats in the specified order.
The main method should create 6 Cat objects.
The program should display 6 lines with information about the cats.
The line about the grandfather (first line) must match the conditions.
The line about the grandmother (second line) must match the conditions.
The line about the father (third line) must match the conditions.
The line about the mother (fourth line) must match the conditions.
The line about the son (fifth line) must match the conditions.
The line about the daughter (sixth line) must match the conditions.

package com.codegym.task.task06.task0621; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; /* Cat relations */ public class Solution { public static void main(String[] args) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); ArrayList<Cat> list = new ArrayList<>(); /*while (true){ String name = reader.readLine(); if (name == null || name.equals("") || name.isEmpty()){ break; }*/ for (int i = 0; i < 6; i++){ String name = reader.readLine(); if (Cat.catNum == 0){ Cat grandFather = new Cat(name); list.add(grandFather); } else if (Cat.catNum == 1){ Cat grandMother = new Cat(name); list.add(grandMother); } else if (Cat.catNum == 2){ Cat father = new Cat(name, null, list.get(0)); list.add(father); } else if (Cat.catNum == 3){ Cat mother = new Cat(name, list.get(1), null); list.add(mother); } else if (Cat.catNum == 4){ Cat son = new Cat (name, list.get(3), list.get(2)); list.add(son); } else if (Cat.catNum == 5){ Cat daughter = new Cat(name, list.get(3), list.get(2)); list.add(daughter); } } for (Cat str : list){ System.out.println(str); } } public static class Cat { private String name; private Cat mother; private Cat father; public static int catNum; private Cat parent; Cat(String name) { this.name = name; catNum++; } Cat(String name, Cat mother, Cat father){ this.name = name; this.mother = mother; this.father = father; catNum++; } @Override public String toString() { if (mother == null && father == null) return "The cat's name is " + name + ", no mother, no father"; else if (mother != null && father == null) return "The cat's name is " + name + ", " + mother.name + " is the mother, no father"; else if (father != null && mother == null) return "The cat's name is " + name + ", no mother, " + father.name + " is the father"; else return "The cat's name is " + name + ", " + mother.name + " is the mother, " + father.name + " is the father"; } } }

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Mike McKenna

Level 25 , Wilmington, United States

31 October 2019, 01:31

Hi, i finished this task while going thru level 6 . i noticed a difference from line 63 thru line 80 . i will add my code .

public static class Cat {
        private String name;
        private Cat father;
        private Cat mother;

        Cat(String name) {
            this.name = name;
        }

        Cat(String name, Cat father, Cat mother) {
            this.name = name;
            this.father = father;
            this.mother = mother;
        }
Hope i helped .

Guadalupe Gagnon

Level 37 , Tampa, United States

30 October 2019, 18:01

solution

Your while loop looks like it is infinite unless a blank value is entered. Because this task does not call for that, the verification system would have locked and failed immediately once a seventh input is requested. The rest of your problem can only be guessed at since, as far as i can tell, the code works as required by the task conditions. I find that sometimes static variables will mess with the verification system, try removing catNum from the cat class and all references to it from your code. In your for loop you can just replace those with the index number of the loop and get the same result. If you are still failing try removing the loop completely.

Guadalupe Gagnon

Level 37 , Tampa, United States

30 October 2019, 18:16

useful

A little tip with if-else if-else statements: try to reduce the amount of boolean checks as much as possible. If yours the first one at line 84 checks if both mother and father are null. If it fails this check then you can reasonably assume that either mother or father (or both) are not null. So you do not need to check again if one is not null and one is null (like on lines 86 and 88). You can rewrite the code like this:

if (mother == null && father == null)
   // return both null
else if (father == null)
   // return mother not null
else if (mother == null)
   // return father not null
else
   // return both not null

Now instead of a minimum of 2 boolean checks (where if both parents were null then the first if statement would execute and return) and a maximum of 6 (where father is not null and mother is), now you have a minimum of 2 and a maximum of 4. However because you are checking both mother and father for null values twice, this is still not that efficient. You could once again rewrite the whole toString method like this:

public String toString() {
   String ma = " no ", pa = " no ";

   if (mother != null) ma = " " + mother.name + " is the ";

   if (father != null) pa = " " + father.name + " is the ";

   return "The cat's name is " + name + "," + ma + "mother," + pa + "father";
}

Now you only have 2 boolean checks max and min. It also cut down on all the duplicate typing. Also debugging is a lot easier now because it uses the same return line for every object (one spelling mistake there can be fixed for every scenario).

Whitney

Level 14 , Onalaska, United States

30 October 2019, 18:53

Removing the static variable was the solution! Thank you! Is there a way to use a while loop for this task? Also thank you for the tips on the boolean!

Guadalupe Gagnon

Level 37 , Tampa, United States

30 October 2019, 18:57

useful

You would just have to make it exit after the 6th input. Off the top of my head would be to make it work like a for loop:

int i = 0;
while(i < 6){
  // code doing something
  i++;
}

but if you are going to do it that way why not use a for loop because that is what they are specifically designed for.