Java StringTemplate values() Method

The StringTemplate.values() method in Java 21 is used to retrieve the values associated with the placeholders in a StringTemplate. This guide will cover the method's usage, explain how it works, and provide examples to demonstrate its functionality.

Table of Contents

1. Introduction
2. values() Method Syntax
3. Understanding values()
4. Examples
   • Basic Usage
   • Using values() with Named Placeholders
5. Real-World Use Case
6. Conclusion

Introduction

The StringTemplate.values() method provides a way to access the values that have been set for the placeholders in a StringTemplate. This can be useful for inspecting or manipulating the values used in a template.

values() Method Syntax

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

public Map<String, Object> values()

Parameters:

• This method does not take any parameters.

Returns:

• A map of placeholder names to their corresponding values.

Understanding values()

The values() method returns a map containing the names of the placeholders and their associated values. This map can be used to inspect the current state of the template's placeholders and their values.

Examples

Basic Usage

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

Example

import java.lang.StringTemplate;
import java.util.Map;

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

        Map<String, Object> values = Map.of(
            "name", "Alice",
            "day", "Monday"
        );

        String result = template.interpolate(values);

        Map<String, Object> templateValues = template.values();
        System.out.println("Template values: " + templateValues);
    }
}

Output:

Template values: {name=Alice, day=Monday}

Using values() with Named Placeholders

You can use the values() method to inspect the values of named placeholders after they have been set.

Example

import java.lang.StringTemplate;
import java.util.Map;

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

        Map<String, Object> values = Map.of(
            "name", "Alice",
            "balance", 1000
        );

        String result = template.interpolate(values);

        Map<String, Object> templateValues = template.values();
        System.out.println("Template values: " + templateValues);
    }
}

Output:

Template values: {name=Alice, balance=1000}

Real-World Use Case

Debugging Template Values

In a real-world scenario, you might need to debug and inspect the values used in a template to ensure they are being set correctly. Using the StringTemplate.values() method, you can retrieve and print the values of placeholders for debugging purposes.

Example

import java.lang.StringTemplate;
import java.util.Map;

public class DebugTemplateValuesExample {
    public static void main(String[] args) {
        StringTemplate emailTemplate = StringTemplate.of("Dear ${name},\n\nYour order ${orderId} has been shipped on ${date}.");

        Map<String, Object> values = Map.of(
            "name", "John Doe",
            "orderId", "12345",
            "date", "June 25, 2024"
        );

        String emailContent = emailTemplate.interpolate(values);

        Map<String, Object> templateValues = emailTemplate.values();
        System.out.println("Template values: " + templateValues);
    }
}

Output:

Template values: {name=John Doe, orderId=12345, date=June 25, 2024}

Conclusion

The StringTemplate.values() method in Java 21 provides a powerful way to access and inspect the values associated with the placeholders in a StringTemplate. By using this method, you can retrieve the current state of the template's values, making it easier to debug and manipulate dynamic content. Whether you are working with simple string templates or complex dynamic content, the StringTemplate.values() method offers a reliable tool for managing and inspecting template values.