CODEWITHSUNDEEP
javaarraysstringposition
Cyberflow
Cyberflow

Reputation: 1305

How to find index of STRING array in Java from a given value?

I wanted to know if there's a native method in array for Java to get the index of the table for a given value ?

Let's say my table contains these strings : 

public static final String[] TYPES = {
        "Sedan",
        "Compact",
        "Roadster",
        "Minivan",
        "SUV",
        "Convertible",
        "Cargo",
        "Others"
    };

Let's say the user has to enter the type of car and that then in the background the program takes that string and get's it's position in the array.

So if the person enters : Sedan It should take the position 0 and store's it in the object of Cars created by my program ...

Upvotes: 64

Views: 252821

Answers (13)

Douglas Rosa
Douglas Rosa

Reputation: 41

Refactoring the above methods and showing with the use:

private String[] languages = {"pt", "en", "es"};
private Integer indexOf(String[] arr, String str){
   for (int i = 0; i < arr.length; i++)
      if(arr[i].equals(str)) return i;
   return -1;
}
indexOf(languages, "en")

Upvotes: 1

user3539787
user3539787

Reputation:

Type in:

Arrays.asList(TYPES).indexOf("Sedan");

Upvotes: 209

Raphael C
Raphael C

Reputation: 2402

No built-in method. But you can implement one easily:

public static int getIndexOf(String[] strings, String item) {
    for (int i = 0; i < strings.length; i++) {
        if (item.equals(strings[i])) return i;
    }
    return -1;
}

Upvotes: 5

suhid
suhid

Reputation: 121

I had an array of all English words. My array has unique items. But using…

Arrays.asList(TYPES).indexOf(myString);

…always gave me indexOutOfBoundException.

So, I tried:

Arrays.asList(TYPES).lastIndexOf(myString);

And, it worked. If your arrays don't have same item twice, you can use:

Arrays.asList(TYPES).lastIndexOf(myString);

Upvotes: 12

mitchell Williamson
mitchell Williamson

Reputation: 1

Use this as a method with x being any number initially. The string y being passed in by console and v is the array to search!

public static int getIndex(int x, String y, String[]v){
    for(int m = 0; m < v.length; m++){
        if (v[m].equalsIgnoreCase(y)){
            x = m;
        }
    }
    return x;
}

Upvotes: 0

abhishek58g
abhishek58g

Reputation: 145

There is no native indexof method in java arrays.You will need to write your own method for this.

Upvotes: 2

Gary Davies
Gary Davies

Reputation: 960

Testable mockable interafce

public interface IArrayUtility<T> {

    int find(T[] list, T item);

}

implementation

public class ArrayUtility<T> implements IArrayUtility<T> {

    @Override
    public int find(T[] array, T search) {
        if(array == null || array.length == 0 || search == null) {
            return -1;
        }

        int position = 0;

        for(T item : array) {

            if(item.equals(search)) {
                return position;
            } else {
                ++position;
            }
        }

        return -1;
    }

}

Test

@Test
public void testArrayUtilityFindForExistentItemReturnsPosition() {
    // Arrange
    String search = "bus";
    String[] array = {"car", search, "motorbike"};

    // Act
    int position = arrayUtility.find(array, search);

    // Assert
    Assert.assertEquals(position, 1);
}

Upvotes: 0

Wayne
Wayne

Reputation: 81

try this instead

org.apache.commons.lang.ArrayUtils.indexOf(array, value);

Upvotes: 8

Arjit
Arjit

Reputation: 3456

Use Arrays class to do this

Arrays.sort(TYPES);
int index = Arrays.binarySearch(TYPES, "Sedan");

Upvotes: 6

R.W
R.W

Reputation: 560

An easy way would be to iterate over the items in the array in a loop. 

for (var i = 0; i < arrayLength; i++) {
 // (string) Compare the given string with myArray[i]
 // if it matches store/save i and exit the loop.
}

There would definitely be better ways but for small number of items this should be blazing fast. Btw this is javascript but same method should work in almost every programming language.

Upvotes: 1

Alaeddine
Alaeddine

Reputation: 1677

Try this Function :

public int indexOfArray(String input){
     for(int i=0;i<TYPES,length();i++)
       {
         if(TYPES[i].equals(input))
         {
          return i ;
         }
        }
      return -1     // if the text not found the function return -1
      }

Upvotes: 0

Mohsen Kamrani
Mohsen Kamrani

Reputation: 7457

for (int i = 0; i < Types.length; i++) {
    if(TYPES[i].equals(userString)){
        return i;
    }
}
return -1;//not found

You can do this too:

return Arrays.asList(Types).indexOf(userSTring);

Upvotes: 13

Anubian Noob
Anubian Noob

Reputation: 13596

String carName = // insert code here
int index = -1;
for (int i=0;i<TYPES.length;i++) {
    if (TYPES[i].equals(carName)) {
        index = i;
        break;
    }
}

After this index is the array index of your car, or -1 if it doesn't exist.

Upvotes: 31

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