Java Enhanced for Loop

By Harish Gowda | | 3 minutes

In this tutorial we will learn how to use enhanced for loop in Java.

You might have used enhanced for loop multiple times while coding.

Enhanced for loop provides a simple way to iterate over arrays and collections without using any explicit index.

Basic syntax:

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for(Type variable: collection){
//code
}
  • Type: Data type of the element in the collection
  • variable: Temporary variable to hold element in the collection
  • collection: Collection used for iteration

Let us discuss them one by one using examples.

1. Using enhanced for loop over an Array

In the below example ’num’ is variable which stores the current element being iterated in the array ’nums’. Also note there is no index used to iterate through the array.

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package examples;
public class App {

    public static void main(String[] args) {

        int[] nums = {100,200,300,400};
        for(int num : nums){
            System.out.print(num+" "); //100 200 300 400
        }

    }
}

2. Using enhanced for loop for string array

Similarly we can use enhanced for loop for string array.

Here ’name’ is the variable which stores the current variable

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package examples;
public class App {

    public static void main(String[] args) {

        String[] names = {"Harish","Shanu","Menaka"};
        for(String name : names){
            System.out.print(name+" ");//Harish Shanu Menaka
        }

    }
}

3. Using enhanced for loop for list

Below example shows how to use enhanced for loop for list.

For a given list ’names’, ’name’ is the variable which holds the current value during iteration.

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package examples;

import java.util.Arrays;
import java.util.List;

public class App {

    public static void main(String[] args) {

        List<String> names = Arrays.asList("Harish","Menaka","Shanu");
        for(String name : names){
            System.out.print(name+" ");//Harish Menaka Shanu
        }

    }
}

4. Using enhanced for loop for HashMap

In the below example, ’entrySet()’ method retrieves key-value pairs. Each iteration gets one entry(key-value pair).

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package examples;

import java.util.HashMap;
import java.util.Map;

public class App {

    public static void main(String[] args) {

        Map<String,Integer> fruits = new HashMap<>();

        fruits.put("Apple",10);
        fruits.put("Orange",5);
        fruits.put("Banana",12);

        for(Map.Entry<String,Integer> entry: fruits.entrySet()){
            System.out.println("Fruits: "+entry.getKey() 
            +" Quantity: "+entry.getValue());
        }

        //Fruits: Apple Quantity:10
        //Fruits: Orange Quantity:5
        //Fruits: Banana Quantity:12


    }
}

5. Using enhanced for loop for iterating over 2D Array

In the below example, outer loop iterated over each row which is a 1D array. Inner loop iterates over elements of the row.

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package examples;


public class App {

    public static void main(String[] args) {

        int[][] nums = {
                {1,2,3},
                {4,5,6},
                {7,8,9}
        };

        for(int[] row: nums){
            for(int num: row){
                System.out.print(num+" ");
            }
            System.out.println();
        }

        //1 2 3
        //4 5 6
        //7 8 9


    }
}

Conclusion:

We can use enhanced loop to iterate over array or collection sequentially. It enables us to write cleaner and more readable code. It works with arrays,lists,sets and maps.

I hope this tutorial was helpful to you!!!