length VS length()

length property:

The length variable is used to return the size of an array, i.e. number of elements stored in an array.

public class Hello{
   public static void main(String args[]) {
      int arr[] = {1, 2, 3, 4, 5, 6, 7};
      System.out.println("Length of an array is: " + arr.length);
   }
}

Output:

Length of an array is: 7

If round brackets come after a Java length property, the following code error occurs:

Cannot invoke length() on the array type int[]

length() method:

The length() method returns the length of a string object i.e. the number of characters stored in an object.

public class Hello {
   public static void main(String args[]) {
      String str = "Welcome";
      System.out.println("Length of String using length() method is: " + str.length());
   }
}

Output:

Length of String using length() method is: 7

If round brackets do not follow a Java length() method call, the following code error occurs:

length cannot be resolved or is not a field

Key differences between length and length()