length vs length() in Java

array.length: length is a final variable applicable for arrays. With the help of the length variable, we can obtain the size of the array. 

string.length() : length() method is a final method which is applicable for string objects. The length() method returns the number of characters present in the string. 

length vs length()

1. The length variable is applicable to an array but not for string objects whereas the length() method is applicable for string objects but not for arrays.

2. Examples:

// length can be used for int[], double[], String[] 
// to know the length of the arrays.

// length() can be used for String, StringBuilder, etc 
// String class related Objects to know the length of the String

3. To directly access a field member of an array we can use .length; whereas .length() invokes a method to access a field member.

Example:  

JAVA

// Java program to illustrate the
// concept of length
// and length()
public class Test {
    public static void main(String[] args)
    {
        // Here array is the array name of int type
        int[] array = new int[4];
        System.out.println("The size of the array is "
                           + array.length);

        // Here str is a string object
        String str = "GeeksforGeeks";
        System.out.println("The size of the String is "
                           + str.length());
    }
}

Output

The size of the array is 4
The size of the String is 13

Practice Questions based on the concept of length vs length()

Let’s have a look at the output of the following programs:

• What will be the output of the following program?

JAVA

public class Test {
    public static void main(String[] args)
    {
        // Here str is the array name of String type.
        String[] str = { "GEEKS", "FOR", "GEEKS" };
        System.out.println(str.length);
    }
}

Output

3

Explanation: Here the str is an array of type string and that’s why str.length is used to find its length.  

• What will be the output of the following program?
  

JAVA

public class Test {
    public static void main(String[] args)
    {
        // Here str[0] pointing to a string i.e. GEEKS
        String[] str = { "GEEKS", "FOR", "GEEKS" };
        System.out.println(str.length());
    }
}

Output: 

error: cannot find symbol
symbol: method length()
location: variable str of type String[]

Explanation: Here the str is an array of type string and that’s why str.length() CANNOT be used to find its length.  

• What will be the output of the following program?

JAVA

public class Test {
    public static void main(String[] args)
    {
        // Here str[0] pointing to String i.e. GEEKS
        String[] str = { "GEEKS", "FOR", "GEEKS" };
        System.out.println(str[0].length());
    }
}

Output

5

Explanation: Here str[0] pointing to String i.e. GEEKS and thus can be accessed using .length()

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