对集合的基础操作
1.boolean add(Object o) //添加对象到集合
2.boolean remove(Object o) //删除指定的对象
3.int size() //返回当前集合中元素的数量
4.boolean contains(Object o) //查找集合中是否有指定的对象。
5.boolean isEmpty() //判断集合是否为空
6.Iterator iterator() //返回一个迭代器
操作整个集合的方法
7.boolean containsAll(Conllection c) //查找集合中是否有集合C中的元素
8.boolean addAll(Conllection c) //将集合c中的所有元素添加给该集合
9.void clear() //删除集合中所有元素
10.void removeAll(Collection c) //从集合中也有的元素
11.void retainAll(Collection c) //从集合中删除集合c中不包含的元素.
对数组操作的方法
12.Object[] toArray() //返回一个包含集合中所有元素的数组
Collection<Person> persons = new ArrayList(<Person>)();
for(Person person :persons){
Sys.out.println(person.name);
}2.使用迭代器Iterator
Collection<Person> persons = new ArrayList<Person>();
Iterator iterator = persons.iterator();
while(iterator.hasNext()){
System.out.println(iterator.next);
}Eenuset SortedSet HashSet TreeSet
Set里面存放的对象是无序，不能重复的，集合中的对象不按特定的方式排序，只是简单的把对象加入集合中。
List里面存放的对象是有序的，同时也是可以重复的，List关注的是索引，拥有一些列和索引相关的方法，查询速度快。
ArrayList LinkedList Vector
Deque priorityQueue ArrayDeque
1. boolean put(key,value) //添加一个map
2. boolean putAll(Map m) //存入一个map
3. boolean remove(key) //删除某一个值
4. boolean clear() //清除所有内容
5. value get(key) //根据键获取某个值
6. boolean isEmpty() //判断是否为空
7. boolean containsKey(key) //判断集合中是否包含指定的key
8. boolean containsValue(value) //判断集合中是否包含某一个值
9. Int size() //Map的长度10.Set KeySet() //返回所有key对象的集合
11.Collection values() //获取所有的值
12.Set entrySet() //将map 集合中的键值映射关系打包成一个对象。Map<Integer,Integer> map = new HashMap<Integer Integer>();
for(Map.Entry<Integer,Integer> entry:map.entrySet()){
System.out.println("key="+entry.getKey()+",Value="+entry.getValue());
}
Map<Integer, Integer> map = new HashMap<Integer, Integer>();
//遍历map中的键
for (Integer key : map.keySet()) {
System.out.println("Key = " + key);
}
//遍历map中的值
for (Integer value : map.values()) {
System.out.println("Value = " + value);
}使用泛型:
Map<Integer,Integer> map = new HashMap<Integer,Integer>();
Iterator<Map.Entry<Integer,Integer>> entries = map.entrySet().interator();
while(entries.hasNext()){
Map.Entry<Integer,Integer> entry = entries.next();
System.out.println("Key = "+entry.getKey()+",Value="+entry.getValue());
}不使用泛型：
Map map = new HashMap();
Iterator entries = map.entrySet().interator();
while(entries.hasNext()){
Map.entry entry = (Map.Entry) entries.next();
Integer key = (Integer)entry.getKey();
Integer value = (Integer)entry.getValue();
System.out.println("key = "+key+",value="+value);
} public static void main(String[] args) throws InterruptedException {
List<String> mylist = new Vector<String>();
List<Thread> myThread = new ArrayList<Thread>();
for(int i=1;i<=5;i++) {
Thread t = new Thread(new Runnable() {
@Override
public void run() {
for (int j = 0; j < 10 ; j++) {
mylist.add("a");
}
}
});
t.start();
myThread.add(t);
}
for (Thread t:myThread) {
t.join();
}
System.out.println(mylist.size());
}Collections.synchronizedList(new ArrayList
public static void main(String[] args) throws InterruptedException {
List<String> mylist = Collections.synchronizedList(new ArrayList<String>());
List<Thread> myThread = new ArrayList<Thread>();
for(int i=1;i<=5;i++) {
Thread t = new Thread(new Runnable() {
@Override
public void run() {
for (int j = 0; j < 10 ; j++) {
mylist.add("a");
}
}
});
t.start();
myThread.add(t);
}
for (Thread t:myThread) {
t.join();
}
System.out.println(mylist.size());
}加入synchronized 锁住代码块
public static void main(String[] args) throws InterruptedException {
List<String> mylist = new Vector<String>();
for(int i=1;i<=5;i++) {
Thread t = new Thread(new Runnable() {
@Override
public void run() {
synchronized (mylist){
for (int j = 0; j < 10 ; j++) {
mylist.add("a");
}
System.out.println(mylist.size());
}
}
});
t.start();
}
}HashSet是根据hashMap来实现的
TreeSet是根据TreeMap来实现的 TreeMap默认支持排序
package core;
public class Product {
private int prodID;
private String ProdName;
public Product(int prodID, String prodName) {
this.prodID = prodID;
ProdName = prodName;
}
public int getProdID() {
return prodID;
}
public void setProdID(int prodID) {
this.prodID = prodID;
}
public String getProdName() {
return ProdName;
}
public void setProdName(String prodName) {
ProdName = prodName;
}
@Override
public int hashCode() {
return (this.getProdName()+String.valueOf(this.getProdID())).hashCode();
}
@Override
public boolean equals(Object obj) {
Product getObj = (Product)obj;
if(this.getProdID()==((Product) obj).getProdID() && this.getProdName()==((Product) obj).getProdName()){
return true;
}else{
return false;
}
}
}Map<String,Integer> user = new TreeMap<String,Integer>((String o1,String o2)->{
return o2.length()-o1.length()+o2.compareTo(o1); //加上Asics码表比较
});
user.put("smartom",20);
user.put("zhangsan",18);
user.put("wangwu",100);
user.put("lisi",20);
for (Map.Entry<String,Integer> entry:user.entrySet()) {
System.out.println(entry.getKey()+":"+entry.getValue());
}package BTree;
import java.util.Comparator;
public class BTree<T> {
Node<T> root = null;
//支持comparator接口
Comparator<T> comparator;
public BTree(Comparator<T> c){
comparator = c;
}
public BTree() {
}
//插值
public void put(T data){
if(root ==null){
root = new Node<T>(data);
}else{
// leftNode
root = addNode(root,data);
}
}
public void list(){
list(root);
}
public void list(Node n){
if(n!=null){
list(n.leftNode);
System.out.println(n.selfdata.toString());
list(n.rightNode);
}
}
Node<T> addNode(Node<T> node,T data){
if(node == null){
return new Node<T>(data);
}
int result = 0; //是那种比较对象
if (comparator!=null) {
result = comparator.compare(data,node.selfdata);
}else{
Comparable<T> comparable = (Comparable<T>)data;
result = comparable.compareTo(node.selfdata);
}
if(result<0){ //小就放左节点
node.leftNode = addNode(node.leftNode,data);
}else if(result > 0){
node.rightNode = addNode(node.rightNode,data);
}
return node;
}
class Node<T>{
private Node<T> leftNode= null;
private Node<T> rightNode = null;
private T selfdata;
public Node(T selfdata) {
this.selfdata = selfdata;
}
}
}BTree<Product> bTree = new BTree<Product>((Product o1,Product o2)->{
return o1.getProdID()-o2.getProdID();
});
bTree.put(new Product(101,"java图书"));
bTree.put(new Product(102,"php图书"));
bTree.put(new Product(1014,"node图书"));
bTree.put(new Product(103,"python图书"));
bTree.put(new Product(105,"esma图书"));
bTree.put(new Product(102,"html图书"));
bTree.list();
BTree<String> bTree2 = new BTree<String>();
bTree2.put("3");
bTree2.put("5");
bTree2.put("7");
bTree2.put("9");
bTree2.put("5");
bTree2.list();Queue
常用方法：
Thread
Thread(String name)
Thread(Runable target)
Thread(Runable target,String name)
线程的方法：
void start() 启动线程
static void sleep(long millis)
static void sleep(long millis,int nanos) 线程休眠
void join() 是其他线程等待当前线程终止
void join(long millis)
void join(long millis,int nanos)
static void yield() 当前运行线程释放 处理器资源原文：https://www.cnblogs.com/subtract/p/8989363.html