Text Templates in Karel

Java provides built-in support for creating dynamic content or showing customized output to the user with the java.util.Formatter class and the String.format() method. For more complex templating needs, there are third-party libraries available such as FreeMarker or Thymeleaf.

import java.util.*;

public class TextTemplates {

    public static void main(String[] args) {
        // We can create a new template using String.format()
        // Templates are a mix of static text and format specifiers
        // enclosed in %s, %d, etc. that are used to dynamically insert content.
        String t1 = "Value is %s\n";

        // By "executing" the template we generate its text with
        // specific values for its format specifiers.
        System.out.printf(t1, "some text");
        System.out.printf(t1, 5);
        System.out.printf(t1, Arrays.asList("Java", "Kotlin", "Scala", "Groovy"));

        // Helper function we'll use below.
        BiFunction<String, String, Formatter> create = (name, t) -> new Formatter();

        // If the data is an object we can use the %s format specifier
        // along with toString() to access its fields. The fields should 
        // be accessible when formatting.
        String t2 = "Name: %s\n";

        System.out.printf(t2, new Person("Jane Doe"));

        // The same applies to maps; with maps there is no restriction on the
        // case of key names.
        Map<String, String> map = new HashMap<>();
        map.put("Name", "Mickey Mouse");
        System.out.printf(t2, map.get("Name"));

        // Java doesn't have built-in conditional execution in its formatting,
        // but we can achieve similar results using ternary operators or if-else statements.
        String t3 = "%s\n";
        System.out.printf(t3, !("not empty".isEmpty()) ? "yes" : "no");
        System.out.printf(t3, !("".isEmpty()) ? "yes" : "no");

        // For looping through collections, we can use a for-each loop
        // or stream operations.
        String t4 = "Range: %s\n";
        List<String> languages = Arrays.asList("Java", "Kotlin", "Scala", "Groovy");
        System.out.printf(t4, String.join(" ", languages));
    }

    static class Person {
        private String name;

        Person(String name) {
            this.name = name;
        }

        @Override
        public String toString() {
            return this.name;
        }
    }
}

When you run this program, you’ll see the following output:

Value is some text
Value is 5
Value is [Java, Kotlin, Scala, Groovy]
Name: Jane Doe
Name: Mickey Mouse
yes
no
Range: Java Kotlin Scala Groovy

This example demonstrates how to use Java’s formatting capabilities to achieve similar results to Go’s text templates. While Java doesn’t have a built-in templating system as powerful as Go’s, it provides string formatting and manipulation tools that can be used for simple templating needs. For more complex scenarios, third-party libraries are often used in Java applications.

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Text Templates in Karel