Passing Strings By Reference in Java

10 May 2025 | 3 min read

In Java, primitive data type variables like int, char, and float are passed by value. It indicates that a duplicate of the variable's value is sent to a method or function. Nonetheless, regarding the passing of objects such as Strings, the distinction between passing by reference and passing by value may occasionally be perplexing.

Understanding Strings as Objects in Java

Strings in Java are objects that denote sequences of characters. They are formed using the String class, and their unchangeability is an essential trait. When handling Strings, any action that seems to alter them actually generates a new String object.

Understanding Passing by Reference vs Passing by Value

When a variable of a primitive data type is provided as an argument to a method, a duplicate of the variable's value is sent. Modifications made to the parameter within the method do not influence the original variable beyond the method.

Output:

 
After method call: Hello, World!

Passing by Reference

When an object is sent as a parameter to a method, the reference to the object's memory address is transmitted rather than a duplicate of the object itself. It indicates that modifications to the object inside the method can be shown in the original object. Nonetheless, in Java, objects are also passed by value; however, it's the value of the reference (the memory address) that gets passed.

Output:

 
After method call: 20

Can we pass string by reference in Java?

Strings in Java are unchangeable, which implies that their content cannot be altered after they have been created. When a String is sent to a method, a duplicate of the reference to the String is sent. Nonetheless, because Strings are immutable, any action that seems to alter the String actually produces a new String object, keeping the original one intact. Let’s examine this through an illustration:

Output:

 
Inside method: World
After method call: Hello

Workaround to Pass Strings by "Reference"

Although Strings are immutable and cannot be directly passed by reference, you can use a wrapper object to achieve similar behaviour. By encapsulating the String inside a mutable object, you can indirectly modify the String. For example:

Output:

 
After method call: Hello World

Modifying Strings Indirectly

While Strings cannot be modified directly due to their immutability, you can use mutable objects such as StringBuilder or StringBuffer to achieve similar functionality. Here is an example:

Output:

 
Inside method: Hello World
After method call: Hello World

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Java Conversion

Java Misc

Passing Strings By Reference in Java

Understanding Strings as Objects in Java

Understanding Passing by Reference vs Passing by Value

Passing by Reference

Can we pass string by reference in Java?

Workaround to Pass Strings by "Reference"

Modifying Strings Indirectly

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