Counting String in an Array

[JohnCR]

Hello All,

I'm hoping someone can help here. I'm trying to count how many times a string occurs in an array. Here is the code I have ...

String animals[] = {"Cat", "Cat", "Dog", "Dog", "Fish"};
String animalSingle[] = {"Cat", "Dog", "Fish"};
count = 0;
for (int i = 0; i < animalSingle.length; i++)
{
System.out.print(animalSingle);
for (j = 0; j < animals.length; j++)
{
if (animals[j] == animalSingle)
{
System.out.print(" " + j + " ");
}
else
{

}
}
}

This will display the animal and the elements that the animal appears, such as this;

Cat 0 1 Dog 2 3 Fish 4

However, I'm looking for how many times each animal appears in the array. So the output will look like this;

Cat 2 Dog 2 Fish 1

Can someone point me in the right direction? I believe it should just be a matter of counting something but I'm not sure what.

Thanks

 

[wangdong]

public class CountAnimal {
	public static void main(String arugs[]) {
		String animals[] = { "Cat", "Cat", "Dog", "Dog", "Fish" };
		String animalSingle[] = { "Cat", "Dog", "Fish" };
		int countCat = 0;
		int countDog = 0;
		int countFish = 0;
		for (int i = 0; i < animalSingle.length; i++) {
			System.out.print(animalSingle[i]);
			for (int j = 0; j < animals.length; j++) {
				if (animals[j] == animalSingle[i]) {
					countCat = animalSingle[i].equals("Cat")?countCat+1:countCat+0;
					countDog = animalSingle[i].equals("Dog")?countDog+1:countDog+0;
					countFish = animalSingle[i].equals("Fish")?countFish+1:countFish+0;
					System.out.print(" " + j + " ");
				}
			}
		}
		System.out.println("\nCats:" + countCat);
		System.out.println("Dogs:" + countDog);
		System.out.println("Fishs:" + countFish);
	}
}

Chinese Java Faq Forum

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[Diancecht]

This is a job for a HashMap.

1.- Loop throught the Strings
2.- Add them as keys in the HashMap
3.- As values, add an Integer and increment it on each ocurrence.
4.- Loop through the HashMap and print the values.

Cheers,
Dian

 

[JohnCR]

Thanks wangdog!

I dont quite understand what this line is doing ...

countCat = animalSingle.equals("Cat")?countCat+1:countCat+0;

Specifically, I dont understand this ....

?countCat+1:countCat+0;

Also, I'm seriously confused about the whole array/arrayList/vector/hash things. There are a lot of options to choose from.

Here's what I'm trying to do. I have a data file and I read the first three characters of each line in that file (I've got this part). Now, the data that I read will be like "AAA BBB CCC AAA DDD BBB" and so on. This can be 30 lines of data or it can be 230 lines of data (So, I would assume an ArrayList because of the Dynamic Sizing capability, is this correct?)

Now then, once I get the first three letters of each line I want to know how many times that three character combination appears in the file.

So, do I use an Arraylist to do this? How do I compare each element to get the number of times certain data appears in the arraylist? I've tried this but it's not working;

for (int i = 0; i < strg.length; i++){
//System.out.print(strg);
for (j = 0; j < arrayList.length; j++){
if (arrayList[j] == strg){
count++;
}
}
}

Thanks in advance for you help!!

JCR

 

[sedj]

The == operator compares the object pointer, not the actual String. Use .equals instead.

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[Diancecht]

expresion?statement1:statement2

means

if (expresion)
 statement1
else
 statement2

And consider the Hashmap option, that would work for a random set of words, not just cats and dogs.

Cheers,
Dian