For-each loop in Java | infoStud blogs

For - each is a way of array traversing technique like for loop, while loop, do-while loop in Java 5.

• Starts with the keyword for similar as for loop.
• declare a variable of the same type as the base type of the array instead of declaring and initializing a loop counter variable followed by a colon.

Syntax:

for (type var : array) 

{ 

    statements using var;

}

is equivalent to:

for (int i=0; i<arr.length; i++) 

{ 

    type var = arr[i];

    statements using var;

}

Example

// Java program to illustrate  

// for-each loop 

class For_Each      

{ 

    public static void main(String[] arg) 

    { 

        { 

            int[] marks = { 125, 132, 95, 116, 110 }; 

              

            int highest_marks = maximum(marks); 

            System.out.println("The highest score is " + 

highest_marks); 

        } 

    } 

    public static int maximum(int[] numbers) 

    {  

        int maxSoFar = numbers[0]; 

          

        // for each loop 

        for (int num : numbers)  

        { 

            if (num > maxSoFar) 

            { 

                maxSoFar = num; 

            } 

        } 

    return maxSoFar; 

    } 

} 

Output:

The highest score is 132

Limitations of the for-each loop

1. For-each loops are not appropriate when you want to modify the array:

   for (int num : marks) 
   {
       // only changes num, not the array element
       num = num*2; 
   }
   

2. For - each loops do not keep track of the index. So we can not obtain array index using For-Each loop

   for (int num : numbers) 
   { 
       if (num == target) 
       {
           return ???;   // do not know the index of num
       }
   }
   

3. For-each only iterates forward over the array in single steps

   // cannot be converted to a for-each loop
   for (int i=numbers.length-1; i>0; i--) 
   {
         System.out.println(numbers[i]);
   }
   

4. For-each cannot process two decision-making statements at once

   // cannot be easily converted to a for-each loop 
   for (int i=0; i<numbers.length; i++) 
   {
       if (numbers[i] == arr[i]) 
       { ...
       } 
   }