List，Set，Map都是接口，前两个继承Collection接口，Map为独立接口
Set的实现由HashSet，LinkedHashSet，TreeSet
List下有ArrayList，Vector，LinkedList
Map下有Hashtable，LinkedHashMap，HashMap，TreeMap
Collection还有Queue接口，实现有PriorityQueue
ArrayList、LinkedList、HashMap中都有字段叫modCount，字段用途：
/**
- The number of times this list has been structurally modified.
- Structural modifications are those that change the size of the
- list, or otherwise perturb it in such a fashion that iterations in
- progress may yield incorrect results.
This field is used by the iterator and list iterator implementation
- returned by the {@code iterator} and {@code listIterator} methods.
- If the value of this field changes unexpectedly, the iterator (or list
- iterator) will throw a {@code ConcurrentModificationException} in
- response to the {@code next}, {@code remove}, {@code previous},
- {@code set} or {@code add} operations. This provides
- fail-fast behavior, rather than non-deterministic behavior in
- the face of concurrent modification during iteration.
Use of this field by subclasses is optional. If a subclass
- wishes to provide fail-fast iterators (and list iterators), then it
- merely has to increment this field in its {@code add(int, E)} and
- {@code remove(int)} methods (and any other methods that it overrides
- that result in structural modifications to the list). A single call to
- {@code add(int, E)} or {@code remove(int)} must add no more than
- one to this field, or the iterators (and list iterators) will throw
- bogus {@code ConcurrentModificationExceptions}. If an implementation
- does not wish to provide fail-fast iterators, this field may be
- ignored.
*/
* 此字段由迭代器和列表迭代器实现使用
此列表在结构上被修改的次数。
结构修改是指改变
列出，或者以这样一种方式干扰它
进度可能会产生不正确的结果。
如果此字段的值意外更改，则迭代器（或列表
迭代器）将在
响应@code next，@code remove，@code previous，
@code set或@code add操作。这提供了
fail fastbehavior，than non determinatic behavior in
迭代期间并发修改的面。
按子类使用此字段是可选的。如果是子类
希望提供fail-fast迭代器（和list迭代器），然后
只需在其@code add（int，e）中增加该字段，
@code remove（int）方法（以及它重写的任何其他方法）
这将导致对列表进行结构修改）。打个电话给
@code add（int，e）或@code remove（int）必须添加不超过
一个到这个字段，或者迭代器（和列表迭代器）将抛出
伪造{@code ConcurrentModificationExceptions}。如果一个实现
不希望提供fail-fast迭代器，此字段可能是
已忽略。
/
List
list.add("config");
list.add("config");
list.add("config1");
list.add("config");
list.add("config");
list.add("config");
list.add("config");
list.add("config");
list.add("config");
list.add("config");
list.add("config");
list.forEach(s -> {
if("config1".equals(s)){
list.remove(s);
}
});
java.util.ConcurrentModificationException
at java.util.ArrayList.forEach(ArrayList.java:1260)
at com.mufeng.test.base.dataStructure.TestList.test1(TestList.java:31)
//HashSet
//巧妙利用HashMap中key实现
private transient HashMap
// Dummy value to associate with an Object in the backing Map
// 仿真的值与Map中对象保持一致
private static final Object PRESENT = new Object();
public HashSet() {
map = new HashMap<>();
}
public boolean add(E e) {
return map.put(e, PRESENT)==null;
}
public boolean remove(Object o) {
return map.remove(o)==PRESENT;
}
//LinkedHashSet
//继承HashSet
public class LinkedHashSet
extends HashSet
implements Set
//初始容量为16
public LinkedHashSet() {
super(16, .75f, true);
}
//LinkedHashMap
//继承HashMap 好多方法都可以用HashMap中的
public class LinkedHashMap
extends HashMap
implements Map
static class Entry
Entry
Entry(int hash, K key, V value, Node
super(hash, key, value, next);
}
}
/**
* The head (eldest) of the doubly linked list.
*/
//单链表 首位
transient LinkedHashMap.Entry head;
/**
* The tail (youngest) of the doubly linked list.
*/
//末位
transient LinkedHashMap.Entry tail;
/**
* The iteration ordering method for this linked hash map: true
* for access-order, false for insertion-order.
*
* @serial
*/
final boolean accessOrder; //TreeSet
//具体实现为TreeMap
private transient NavigableMap
// Dummy value to associate with an Object in the backing Map
//仿真值
private static final Object PRESENT = new Object();
public TreeSet() {
this(new TreeMap());
}
//利用TreeMap的key
public boolean add(E e) {
return m.put(e, PRESENT)==null;
}
public boolean remove(Object o) {
return m.remove(o)==PRESENT;
}