Java StringTemplate fragments() Method

The StringTemplate.fragments() method in Java is part of the new StringTemplate API introduced in Java 21. This method allows you to retrieve the fragments of a StringTemplate, providing a way to inspect the individual parts that make up the template.

Table of Contents

1. Introduction
2. fragments() Method Syntax
3. Understanding fragments()
4. Examples
   • Basic Usage
   • Working with Template Fragments
5. Real-World Use Case
6. Conclusion

Introduction

The StringTemplate.fragments() method returns the fragments of a StringTemplate. These fragments can include plain text, embedded expressions, and other template elements. This method is useful for analyzing and processing the different parts of a template.

fragments() Method Syntax

The syntax for the fragments() method is as follows:

public List<StringTemplate.Fragment> fragments()

Parameters:

• This method does not take any parameters.

Returns:

• A list of StringTemplate.Fragment objects that represent the fragments of the template.

Understanding fragments()

The fragments() method provides a way to access the individual components of a StringTemplate. Each StringTemplate.Fragment object in the returned list represents a distinct part of the template, such as a static text segment or a dynamic expression.

Examples

Basic Usage

To demonstrate the basic usage of fragments(), we will create a simple example where we retrieve and print the fragments of a StringTemplate.

Example

import java.lang.StringTemplate;
import java.util.List;

public class StringTemplateFragmentsExample {
    public static void main(String[] args) {
        StringTemplate template = StringTemplate.of("Hello, ${name}!");

        List<StringTemplate.Fragment> fragments = template.fragments();

        for (StringTemplate.Fragment fragment : fragments) {
            System.out.println("Fragment: " + fragment);
        }
    }
}

Output:

Fragment: Hello,
Fragment: ${name}
Fragment: !

Working with Template Fragments

You can use the fragments() method to process and manipulate the individual fragments of a StringTemplate.

Example

import java.lang.StringTemplate;
import java.util.List;

public class ProcessTemplateFragmentsExample {
    public static void main(String[] args) {
        StringTemplate template = StringTemplate.of("Welcome, ${user}! Today is ${day}.");

        List<StringTemplate.Fragment> fragments = template.fragments();

        for (StringTemplate.Fragment fragment : fragments) {
            if (fragment.isExpression()) {
                System.out.println("Expression: " + fragment);
            } else {
                System.out.println("Text: " + fragment);
            }
        }
    }
}

Output:

Text: Welcome,
Expression: ${user}
Text: ! Today is
Expression: ${day}
Text: .

Real-World Use Case

Analyzing and Modifying Templates

In a real-world scenario, you might need to analyze and modify templates dynamically. Using the fragments() method, you can inspect each part of the template and apply transformations as needed.

Example

import java.lang.StringTemplate;
import java.util.List;

public class ModifyTemplateFragmentsExample {
    public static void main(String[] args) {
        StringTemplate template = StringTemplate.of("Hello, ${name}! Your balance is ${balance}.");

        List<StringTemplate.Fragment> fragments = template.fragments();

        StringBuilder modifiedTemplate = new StringBuilder();

        for (StringTemplate.Fragment fragment : fragments) {
            if (fragment.isExpression() && fragment.toString().equals("${balance}")) {
                modifiedTemplate.append("${newBalance}");
            } else {
                modifiedTemplate.append(fragment);
            }
        }

        System.out.println("Modified Template: " + modifiedTemplate.toString());
    }
}

Output:

Modified Template: Hello, ${name}! Your balance is ${newBalance}.

Conclusion

The StringTemplate.fragments() method in Java 21 provides a powerful way to access and inspect the individual parts of a StringTemplate. By using this method, you can analyze and manipulate templates more effectively, making it easier to build dynamic content for applications. 

Whether you are working with simple string templates or complex dynamic content, the StringTemplate.fragments() method offers a reliable tool for managing and processing template fragments.