java - Thinking in Java 4th Edition——什么是classname.this.method()

Question

阅读“Thinking in Java 4th Edition”我在第 14 章找到了这个例子:

public class CoffeeGenerator
implements Generator<Coffee>, Iterable<Coffee> {
  private Class[] types = { Latte.class, Mocha.class,
    Cappuccino.class, Americano.class, Breve.class, };
  private static Random rand = new Random(47);
  public CoffeeGenerator() {}
  private int size = 0;
  public CoffeeGenerator(int sz) { size = sz; } 
  public Coffee next() {
    try {
      return (Coffee)
        types[rand.nextInt(types.length)].newInstance();
    } catch(Exception e) {
      throw new RuntimeException(e);
    }
  }
  class CoffeeIterator implements Iterator<Coffee> {
    int count = size;
    public boolean hasNext() { return count > 0; }
    public Coffee next() {
      count--;
      return CoffeeGenerator.this.next();
    }
    public void remove() {
      throw new UnsupportedOperationException();
    }
  };    
  public Iterator<Coffee> iterator() {
    return new CoffeeIterator();
  }
}

而且我注意到我从未遇到过这种构造:

return CoffeeGenerator.this.next();

这是什么意思？我知道 ClassName.class.Method()，但这意味着什么？

Answer 1

CoffeeGenerator.this 允许从内部类 CoffeeIterator 访问外部类 CoffeeGenerator

JLS 15.8.4将其描述为合格的 this

Any lexically enclosing instance (§8.1.3) can be referred to by explicitly qualifying the keyword this.

阅读:Inner classes