Find a String in ArrayList of objects - java

Question

I wrote a program that consists of an ArrayList, which contains objects. Every object has a name. I want to find the index in ArrayList with the same name as i would input it with scanner. I tried the following code, but it doesnt work. q=0; while(!naziv.equals(racuni.get(q).getNaziv())) q++;

Because the array list contains two objects. The one with index 0 and another with index one — jeprubio, Jan 03 '18 at 15:04
The exception message tells you exactly what's wrong: You're trying to access Index 2 and the list has only size 2! (Index 0 and 1 in the list) — ParkerHalo, Jan 03 '18 at 15:05
Possible duplicate of [What is a debugger and how can it help me diagnose problems?](https://stackoverflow.com/questions/25385173/what-is-a-debugger-and-how-can-it-help-me-diagnose-problems) — Turing85, Jan 03 '18 at 15:07
i get that, but my input string is the same one as the String of the index 0 — AsYouWereAPx, Jan 03 '18 at 15:08
Possible duplicate of [What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?](https://stackoverflow.com/questions/5554734/what-causes-a-java-lang-arrayindexoutofboundsexception-and-how-do-i-prevent-it) — jeprubio, Jan 03 '18 at 15:11

Greggz · Answer 1 · 2018-01-03T15:28:59.370

2

First let's format your code clearly

String name = sc.next();
int q=0;
while(q < object.size() && !name.equals(object.get(q).getName())) {
  q++;
}

Second, you must verify that q also is below the ArrayList size, cause it wouldn't make sense if you tried to access a position bigger than your Array.

Here have a sample

    ArrayList<Animal> object = new ArrayList<Animal>();
    object.add(new Animal("duck"));
    object.add(new Animal("chicken"));
    Scanner sc = new Scanner(System.in);
    String name = sc.next();
    int q = 0;
    while (q < object.size() && !name.equals(object.get(q).getName())) {
        q++;
    }
    System.out.print(q);

// Prints 0 if you write "duck"

// Prints 1 if you write "chicken"

// Prints 2 if you write "NotInArrayList"

edited Jan 03 '18 at 15:28

answered Jan 03 '18 at 15:05

Greggz

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It prints out exactly the same thing, if I put in the String of zero index, but if I put in the name of the first index it works – AsYouWereAPx Jan 03 '18 at 15:14
@AnaPeterka Let me test it out 1 second – Greggz Jan 03 '18 at 15:17
@AnaPeterka Compare your version to mine and figure out what's wrong in yours. Or post more of your code for us to figure out what you did wrong. Cheers :) – Greggz Jan 03 '18 at 15:24
I figured out that when i input another name, that name replaces the name that was there before – AsYouWereAPx Jan 04 '18 at 13:10
@AnaPeterka That doesn't happen in my code. Again, try out my code, or post the rest of your code for we to analyze what's wrong in yours – Greggz Jan 04 '18 at 14:17

score 0 · Answer 2 · answered Jan 03 '18 at 17:30

Simple way to solve this problem in JAVA8 is by using Stream

If element is available in list, it prints the first index of element, else returns -1.

OptionalInt findFirst = IntStream.range(0, objects.size())
.filter(object-> objects.get(object).getName().equals(nextLine))
.findFirst();
System.out.println(findFirst.isPresent() ? findFirst.getAsInt() : -1);

Find a String in ArrayList of objects - java

2 Answers2