The WeakReference class, monitoring memory leak and garbage collection in a Java application

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 Below is a Stack implementation that uses an internal resizeable array structure.  public class MyStack< T > implements Stack< T > { private static final int CAPACITY = 100 ; private Object[] array ; private int pos = 0 ; public MyStack () { this . array = new Object[ CAPACITY ] ; } @Override public void push ( T item) { if ( pos >= array . length / 2 ) { Object[] newArray = new Object[ pos * 2 ] ; System. arraycopy ( array , 0 , newArray , 0 , array . length ) ; array = newArray ; } array [ pos ++] = item ; } @Override public T pop () { if (isEmpty()) { throw new RuntimeException( "empty stack" ) ; } @SuppressWarnings ( "unchecked" ) T item = ( T ) array [ pos - 1 ] ; pos -= 1 ; return item ; } @Override @SuppressWarnings ( "unchecked" ) public T peek...
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Java 8 ile gelen Lambda Expressions özelliğine merhaba diyelim

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Lambda ifadeleri C# dilinde yıllardır vardı ve sonunda Java diline de bu özellik eklendi. Peki bu lambda expression özelliği hangi amaçla kullanılıyor?
Amacımız şu: Belli bir işi yapma biçimini (fonksiyonaliteyi), bir metoda parametre olarak geçmek istiyoruz. Başka bir deyişle, kodu sanki veriymiş gibi parametre olarak geçmek istiyoruz. Peki eskiden bunu yapamıyormuyduk Java ile? Yapabiliyorduk ama Anonymous class yöntemi ile yapabiliyorduk. Aşağıda vereceğim basit örnekte aradaki farkı görebileceğiz:

public class Program {

    public static class Person {
        private int age;
        private String name;

        Person(String name, int age) {
            this.age = age;
            this.name = name;
        }

        public int getAge() {
            return age;
        }

        public String getName() {
            return name;
        }
    }

    public interface GreetingMethod {
        int howManyTimes(Program.Person p);
    }

    public static void main(String[] args) {

        Person bahadir = new Person("Bahadir", 32);
        Person bilge = new Person("Bilge", 2);

        Person anonymous = new Person("Anon", 18);

        // Lambda expression ile:
        new Program().greet(bahadir, p -> p.getAge() > 30 ? 2 : 1);
        new Program().greet(bilge, p -> p.getAge() > 20 ? 2 : 1);

        // Anonymous class ile pek de sade bir görünüm yok gibi:
        new Program().greet(anonymous, new GreetingMethod() {
            @Override
            public int howManyTimes(Person p) {
                if (p.getAge() > 10)
                    return 2;

                return 0;
            }
        });

    }

    public void greet(Person person, GreetingMethod greetingMethod) {

        for (int i = 0; i < greetingMethod.howManyTimes(person); ++i) {
            System.out.println("Hello " + person.getName() + "!");
        }

    }
}

Lambda ifadeleri, tek metotlu arayüzleri daha sade bir biçimde parametre olarak geçmemize olanak tanıyor.
Geçen gün izlediğim bir sunumda, konuşmacı lamda ifadesi içeren bir örnek verecekti ama önce Java programcılarını korkmamaları için uyarmıştı. Artık böyle bir uyarıya gerek kalmayacak.

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