LinkHash**特性：唯一和有序
由【哈希表】保证【键】的唯一性，由【链表】保证【键】的有序性(存储和取出的顺序一致) 【LinkHashSet】和【LinkHashMap key】的特性是完全一样的！public class Test { public static void main(String[] args) { LinkedHashMap<Person, String> linkedHashMap = new LinkedHashMap<Person, String>(); linkedHashMap.put(new Person("ea", 150), "包青天"); linkedHashMap.put(new Person("ab", 27), "包青天"); linkedHashMap.put(new Person("c", 150), "包青天"); linkedHashMap.put(new Person("c", 160), "baiqiantao"); linkedHashMap.put(new Person("ea", 160), "baiqiantao"); linkedHashMap.put(new Person("d", 27), "包青天"); System.out.println(linkedHashMap);//{ea,150=baiqiantao, ab,27=包青天, c,150=baiqiantao, d,27=包青天} } }
class Person { public String name; public int age; public Person(String name, int age) { this.name = name; this.age = age; } public int hashCode() { int newAge = this.age; if (age > 150) newAge = 150; return name.hashCode() + newAge;//这里的hashCode是基于String类的hashCode更改的 } public boolean equals(Object obj) { if (this == obj) return true; if (!(obj instanceof Person)) return false; Person p = (Person) obj; return this.name.equals(p.name);//只要name相同就认为equal值为true } public String toString() { //默认返回值是【person.getClass().getName() + ‘@‘ + Integer.toHexString(person.hashCode())】 return name + "," + age; } }
public class Test {
public static void main(String[] args) {
LinkedHashMap<Person, String> linkedHashMap = new LinkedHashMap<Person, String>();
linkedHashMap.put(new Person("ea", 150), "包青天");
linkedHashMap.put(new Person("ab", 27), "包青天");
linkedHashMap.put(new Person("c", 150), "包青天");
linkedHashMap.put(new Person("c", 160), "baiqiantao");
linkedHashMap.put(new Person("ea", 160), "baiqiantao");
linkedHashMap.put(new Person("d", 27), "包青天");
System.out.println(linkedHashMap);//{ea,150=baiqiantao, ab,27=包青天, c,150=baiqiantao, d,27=包青天}
}
}
Collection案例:模拟斗地主的牌局
public class Test {
public static void main(String[] args) {
// 创建一个牌盒
List<PokerBean> list = new ArrayList<PokerBean>();
String[] colors = { "?", "?", "?", "?" };
String[] numbers = { "A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K" };
// 装牌
for (int i = 0; i < numbers.length; i++) {
for (String color : colors) {
list.add(new PokerBean(color, numbers[i], i + 1));
}
}
list.add(new PokerBean("小王", "小王", 14));
list.add(new PokerBean("大王", "小王", 15));
// 洗牌
Collections.shuffle(list);
// 发牌
Set<PokerBean> player_1 = new TreeSet<PokerBean>();
Set<PokerBean> player_2 = new TreeSet<PokerBean>();
Set<PokerBean> player_3 = new TreeSet<PokerBean>();
Set<PokerBean> diPai = new TreeSet<PokerBean>();
for (int x = 0; x < list.size(); x++) {
if (x >= list.size() - 3) diPai.add(list.get(x));
else if (x % 3 == 0) player_1.add(list.get(x));
else if (x % 3 == 1) player_2.add(list.get(x));
else if (x % 3 == 2) player_3.add(list.get(x));
}
//看牌
System.out.println("玩家一的牌为：" + player_1);
System.out.println("玩家二的牌为：" + player_2);
System.out.println("地主家的牌为：" + player_3);
System.out.println("底牌为：" + diPai);
}
}
class PokerBean implements Comparable<PokerBean> {
public String color;
public String numberString;
public int numberInt;
public PokerBean(String color, String numberString, int numberInt) {
this.color = color;
this.numberString = numberString;
this.numberInt = numberInt;
}
@Override
public String toString() {
switch (numberInt) {
case 10:
return "[" + color + numberString + "]";//没有空格
case 14:
case 15:
return "[" + numberString + "]";//没有空格，没有数字
default:
return "[ " + color + numberString + " ]";
}
}
@Override
public int compareTo(PokerBean o) {
int tem = this.numberInt - o.numberInt;
return tem == 0 ? this.color.compareTo(o.color) : tem;
}
}
TreeMap案例:统计字符出现的次数
public class Test {
public static void main(String[] args) {
String str = "fd*+a//dA11 \n aDdD-d";
System.out.println(getcharCount(str));
}
// 获取字符串中每一个字母出现的次数，要求打印结果形式为：a-2 \n b-1 形式
public static String getcharCount(String str) {
TreeMap<Character, Integer> map = new TreeMap<Character, Integer>();
char[] arr = str.toCharArray();
for (int i = 0; i < arr.length; i++) {
if (!(arr[i] <= ‘z‘ && arr[i] >= ‘a‘ || arr[i] <= ‘Z‘ && arr[i] >= ‘A‘)) //限制查询范围
continue;//表示不再执行后面的代码，继续下次遍历！
Integer value = map.get(arr[i]);//Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.
if (value == null) map.put(arr[i], 1);//若此字符不存在，则存入此字符，将值设为1
else map.put(arr[i], value + 1);//若此字符已经存在，则值加1
}
return mapToString(map);
}
//将集合中的内容以指定格式的字符串形式返回
private static <K, V> String mapToString(Map<K, V> map) {
StringBuilder sb = new StringBuilder();
Iterator<K> it = map.keySet().iterator();
while (it.hasNext()) {
K key = it.next();
V value = map.get(key);
sb.append(key + "-" + value + "\n");
}
return sb.toString();
}
}
时间： 2024-10-09 17:36:55