Demo of Lambda Expressions

Lambda.java

import java.util.HashMap;
import java.util.Map;

public class Lambda {
    enum Attribute { NAME, AGE };
    interface ToString<T> { String toString(T object); };
    
    public static void main(final String[] args) throws Exception {
        final Map<Attribute, ToString<Person>> mapping = new HashMap<>();
        
        // Here are the Lambda Expressions
        mapping.put(Attribute.NAME, Person#getName);
        mapping.put(Attribute.AGE, (p) -> Integer.toString(p.getAge()));
        
        final Person person = new Person("Scott", 29);
        System.out.printf("%s is %s.\n",
            mapping.get(Attribute.NAME).toString(person),
            mapping.get(Attribute.AGE).toString(person));
    }    
}

class Person {
    private final String name;
    private final int age;
    
    public Person(final String name, final int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() { return name; }
    public int getAge() { return age; }
}