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Thread: Arraylist indexof problem

  1. #1
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    Default Arraylist indexof problem

    mainData.java

    public class mainData{
        public animalsData animal = new animalsData();
        public static void main(String[] args) {
        	mainData mn = new mainData();
        	mn.newAnimal();
        }
        public void newAnimal(){
        	animal.create("CAT", "4");
        	animal.create("DOG", "5");
        	System.out.println(animal.animalIndex("DOG"));
        }
    }

    animalsData.java

    public class animalsData{
        String name, l;
        ArrayList<animalsData> animals = new ArrayList<animalsData>();
        public animalsData(){}//def constructor
        public animalsData(String name, String l){
        	super();
        	this.name= name;
        	this.l= l;
        }
        public void create(String name, String l){
        	animals.add(new animalsData(name, l));
        }
        public int animalIndex(String name){
        	return this.animals.indexOf(name);
        }
    }
    create method working normally and add object to list, but when i call animalIndex method i given this problem;
    **return only -1 why?**


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Arraylist indexof problem

    return only -1 why?
    What does the API doc say about the values that the indexOf() method returns? Read that for the explanation.

    What does the ArrayList: animals contain? You are looking in it for a String. It does not contain any String objects so indexOf() won't find the String: name.
    If you don't understand my answer, don't ignore it, ask a question.

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