JDK源码==》LinkedHashSet类学习

public class linkedHashSet
    extends HashSet
    implements Set, Cloneable, java.io.Serializable {
    
    
    public linkedHashSet(int initialCapacity, float loadFactor) {
        super(initialCapacity, loadFactor, true);
    }
    
    public linkedHashSet(int initialCapacity) {
        super(initialCapacity, .75f, true);
    }
    
    public linkedHashSet() {
        super(16, .75f, true);
    }
    
    public linkedHashSet(Collection c) {
        super(Math.max(2*c.size(), 11), .75f, true);
        addAll(c);
    }
}    

从上面可以看出该类继承HashSet，构造都是调用父类的构造

    public HashSet() {
        map = new HashMap<>();
    }
	public HashSet(Collection c) {
        map = new HashMap<>(Math.max((int) (c.size()/.75f) + 1, 16));
        addAll(c);
    }
	public HashSet(int initialCapacity, float loadFactor) {
        map = new HashMap<>(initialCapacity, loadFactor);
    }
	public HashSet(int initialCapacity) {
        map = new HashMap<>(initialCapacity);
    }
	HashSet(int initialCapacity, float loadFactor, boolean dummy) {
        map = new linkedHashMap<>(initialCapacity, loadFactor);
    }

从上面可以看出，当linkedHashSet使用无参构造实例化时，回调用父类HashSet的三个参数的构造，而调用父类的三个参数的构造，默认创建的是linkedHashMap的实例。

而HashSet使用无参构造创建的实例是HashMap的实例。

linkedHashSet的构造可以看出，全部都是调用父类的三个参数的构造，因此linkedHashSet创建的实例都是linkedHashMap