Length Vs Length Method In Java – Learn More

These two can be very confusing when you are new to Java, especially if you are coming with no programming experience or from another programming language. The Length Vs Length Method perform two different functions and have unrelated uses in Java.

Length Vs Length Method In Java - Learn More

The Difference Between length and length()

In Java programming, length () is a method and is used to return the number of characters in a String, which is also the length or size of the String. On the other hand, length is used to determine the length of an array and is a final variable. To clarify, in Java programming a final variable is one that cannot be changed once declared. This means the size of the array cannot be changed once it has been created.

An In-Depth Comparison of length and length() Method in Java

The length() String method returns the length as an integer value. It is important to note that the length array variable does not count the number of elements in the array but rather the length of the array itself, that is how many elements can be stored in the array including the ones that are not in the array yet. Below is a table comparing the two.

Table 1: Comparison of length and length()

Propertylengthlength()
Data typeField/variablemethod
Mutable/ImmutableMutableImmutable
UsesFind the capacity of an arrayFind the length of a string
Return valueintegerinteger
What does it countArray capacity/ lengthlength of string/ number of characters in a string

Examples of Using length 

public class Main

{

public void static main()

{

intArr1 = new int [2];

intArr1[0] = 1;

System.out.print(intArr1.length);

  }

}

In the code snippet above will return 2. Even though there is only 1 element currently in the array, the capacity of the array is still 2. This shows that the length variable returns the capacity and not the number of elements. The same output would be returned if we write the code as follows:

public class Main

{

public void static main()

{

intArr1 = new int [2];

intArr1[0] = 1;

intArr1[1] = 2;

System.out.print(intArr1.length);

  }

}

So even if we filled in the second element of the array. The output of the above snippet would still be 2, as this is the capacity of the array.

Examples of Using length()

public class main

{

public void static main(String[] args)

{

String name = “Louis”;

System.out.println(name.length());

}

}

The output of the code above will be 5. This is the length of the String name and is also the number of characters in name. Unlike with the length variable, the length method returns the size of the String which is also its capacity. If you were to add a letter or two the output of the above would change, just like in the code snippet below.

Public class main

{

public void static main (String[] args)

{

Char toBeAdded = ‘a’;

String name = “Louis”;

String newName = name + toBeAdded;

System.out.println(newname.length())

}

}

In this case the output would no longer be 5 b 6 since 1 more character was added to change “Louis” to “Louisa”. This is one of the differences between length() and length. In the array version (length), the output will never change because the capacity of the array cannot be changed. While with length() ,the output can change if the string is changed by added or removing characters.

In What Scenario Can I Use length?

If you are writing a program in Java that includes some array, you might want to write some logic using that array. Sometimes this logic may require you to know how many elements are in the array or even the size of the array. For example, you may want to write some logic to add elements to the array, to do this, you will first need to know how many elements the array can hold. This would be the right time to use the length variable to find this information.

In What Scenario Can I Use length()?

Like using the array version, the String version can be used in a program where you have a String, and you might need to perform some logic. You would most likely need to find out the size of the string before you can start doing anything with it.

For example, in a program that returns the longest name based of the input of a few users, you can use this method to get the length of each name, compare them and return the longest one. 

Conclusion

As we can see from the information above, length() and length are very different despite sounding the same. They do not even belong to the same data type. While it may be confusing at first as to why it was made this way, we need to remember that Java is a very old Object-Oriented Programing language. Back when languages like Java were created, you as the developer needed to tell Java what data type you were declaring or working with. 

This means that there could not be a method that is used to different data types because each method has a specific data type that it takes in. If it does get too confusing to remember or differentiate between the two, an easy way to do so would be thinking of thee brackets in the String version and no brackets in the array version. This will also help you remember that the String version is a method and thee array version is a variable/field.

Frequently Asked Questions

  1. Will length return a different value if the array size changes?

No, the size of arrays in Java cannot be changed, so length will always return the same size for the same array.

  1. Can I use length() or length to find the sizes of lists?

No, the length() method is a member of the String class. To find the sizes of lists the Size() method can be used.

Length Vs Length Method In Java – Learn More

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