Strings are immutable Java objects, which don’t allow you to modify any part of the string. So string interpolation is vital to allow you to use this approach.

The process replaces all placeholders with a string literal values. This article will introduce various ways to do string interpolation in Java.

What Is String Interpolation?

String interpolation is a data process, involving the placeholder characters being replaced with the variables or strings. The processing allows users to print out the text outputs efficiently and dynamically.

Thanks to string interpolation, the code becomes more compact and eliminates the risk of repetition of variables. This way, it lets coders write large variable text and names.

How To Do String Interpolation In Java

Method 1: Use + Operator

Using this concatenation is undoubtedly the simplest approach to do string interpolation. When employing this method, you will likely concatenate various variables in a string.

Remember to use the + operator before or after the string or variable name, depending on the given condition. In this case, such variables will be replaced with their values and make the concatenation and interpolation available.

Code:

public class SimpleTesting{
    public static void main(String[] args) {
        String site_name = "ITtutoria";
        String type = "'How to Guide'";
        String message = site_name+" is a "+ type + " Portal";
        System.out.println(message);
    }
}

Method 2: Use The format() Function

The format() function enables users to interpolate variables to format a string. It takes two parameters, including string format and the list of arguments.

The method focuses on separating the text with the variable name and expression. This way, it keeps the code easy to follow and compact for small expressions and sentences.

With the parameters, the placeholders can fit sequentially in the variables’ values. The string will be accepted as the first parameter with the variables behind. For this reason, you will get one parameter more than the string’s placeholders.

public class SimpleTesting{
    public static void main(String[] args) {
        String site_name = "ITtutoria";
        String type = "'How to Guide'";
        String message = String.format("%s is a %s portal", site_name,type);
        System.out.println(message);
    }
}

Method 3: Use The MessageFormat Class

This approach offers users a format() method to perform string interpolation. To get the format function and use this one, it is vital to import the MessageFormat class.

The format function in this class is similar to the one in the String class. The only difference lies in the placeholders, which are written in a different manner.

Here, they are executed with such indexes as {0}, {1}, and {2}. This form of placeholders helps avoid unwanted repetition of the same variables.

import java.text.MessageFormat;

public class SimpleTesting{
    public static void main(String[] args) {
        String site_name = "ITtutoria";
        String type = "'How to Guide'";
        String message = MessageFormat.format("{0} is a {1} Portal", site_name, type);
        System.out.println(message);
    }
}

Method 4: Use The StringBuilder Class

Using the StringBuilder class is often complicated and lengthy, thus it is not suitable for beginners. Its main function is to instantiate a new object and employ the append() function.

The StringBuilder mutable version can be modified with various variables at once. Yet, it can easily disorient the code’s readability.

public class SimpleTesting{
    public static void main(String[] args) {
        String site_name = "ITtutoria";
        String type = "'How to Guide'";
        StringBuilder message = new StringBuilder(site_name).append(" is a ").append(String.valueOf(type)).append(" Portal");
        System.out.println(message);
    }
}

Conclusion

The post discusses four methods to do string interpolation in Java. The best method should depend on the balance between the code’s readability and scalability.

All recommended approaches are commonly used, so you easily get up and execute them with the basics of the syntax and minimal code.