集合嵌套练习题
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2022-07-12 09:36:06
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List嵌套List
public static void main(String[] args) {
//建立集合，存储字符串
List<String> smallList = new ArrayList<>();
smallList.add("how");
smallList.add("are");
smallList.add("you");
smallList.add("yyx");
List<String> smallList2 = new ArrayList<>();
smallList.add("how");
smallList.add("do");
smallList.add("you");
smallList.add("do");
//建立集合，存储小集合
List<List<String>> bigList = new ArrayList<>();
//小集合，存储大集合
bigList.add(smallList);
bigList.add(smallList2);
iterator(bigList);
}
/*
* 方法,遍历集合,遍历是大集合
*/
public static void iterator(List<List<String>> bigList) {
//迭代器，遍历大集合
Iterator<List<String>> bigit = bigList.iterator();
while(bigit.hasNext()) {
List<String> smallList = bigit.next();
Iterator<String> smallIt = smallList.iterator();
while(smallIt.hasNext()) {
String string = smallIt.next();
System.out.println(string);
}
}
}
List嵌套Map
public static void main(String[] args) {
//创建Map集合，键值字符串
Map<String, String> bigMap1 = new HashMap<String, String>();
bigMap1.put("a", "1");
bigMap1.put("b", "2");
bigMap1.put("c", "3");
Map<String, String> bigMap2 = new HashMap<String, String>();
bigMap2.put("aa", "11");
bigMap2.put("bb", "22");
bigMap2.put("cc", "33");
List<Map<String, String>> bigList = new ArrayList<Map<String,String>>();
bigList.add(bigMap1);
bigList.add(bigMap2);
iterator(bigList);
}
public static void iterator(List<Map<String, String>> bigList) {
Iterator<Map<String, String>> bigIt = bigList.iterator();
while(bigIt.hasNext()) {
Map<String, String> map = bigIt.next();
//keySet遍历map
Set<String> set = map.keySet();
Iterator<String> setIt = set.iterator();
while(setIt.hasNext()) {
String key = setIt.next();
String value = map.get(key);
System.out.println(key+"=="+value);
}
}
}
Map嵌套Map
public static void main(String[] args) {
//阶段集合,包含学号,姓名
Map<String, String> firstMap = new HashMap<String, String>();
//第一阶段,集合,存储字符串
firstMap.put("001", "张三");
firstMap.put("002", "李四");
Map<String, String> secondMap = new HashMap<String, String>();
//第二阶段集合,存储字符串
secondMap.put("003", "王五");
secondMap.put("004", "赵六");
//创建学科集合, 键是阶段名,值是阶段 集合
Map<String, Map<String, String>> javaMap = new HashMap<String, Map<String,String>>();
javaMap.put("第一", firstMap);
javaMap.put("第二", secondMap);
//keySet(javaMap);
entrySet(javaMap);
}
/*
* 方法遍历javaMap集合,entrySet()方式
*/
public static void entrySet(Map<String, Map<String, String>> javaMap) {
//学科集合javaMap,方法entrySet(),获取学科集合的键值对,映射关系对象Entry
Set<Map.Entry<String, Map<String, String>>> javaMapEntrySet = javaMap.entrySet();
//迭代器,遍历Set集合
Iterator<Map.Entry<String, Map<String, String>>> javaMapEntryIt = javaMapEntrySet.iterator();
while(javaMapEntryIt.hasNext()) {
//取出Set集合元素,元素是javaMap学科集合的键值对关系对象
Map.Entry<String, Map<String, String>> javaMapEntry = javaMapEntryIt.next();
//获取javaMap阶段集合的键,是阶段名
String javaMapKey = javaMapEntry.getKey();
//获取javaMap集合值,是阶段的集合 (姓名,学号)
Map<String, String> jieDuanMap = javaMapEntry.getValue();
//遍历阶段jieDuanMap,方法entrySet()取出集合的键值对映射关系对象
Set<Map.Entry<String, String>> jieDaunEntrySet = jieDuanMap.entrySet();
//迭代器,遍历Set集合
Iterator<Map.Entry<String, String>> jieDuanEntryIt = jieDaunEntrySet.iterator();
while(jieDuanEntryIt.hasNext()) {
//取出Set集合的键,是阶段集合的键值对映射关系对象
Map.Entry<String, String> jieDuanMapEntry = jieDuanEntryIt.next();
//阶段集合的键,学号
String key = jieDuanMapEntry.getKey();
//阶段集合的值,姓名
String value = jieDuanMapEntry.getValue();
System.out.println(javaMapKey+"=="+key+"=="+value);
}
}
}
/*
* 方法遍历javaMap集合,keySet()方式
*/
public static void keySet(Map<String, Map<String, String>> javaMap) {
//学科Map集合,遍历,方法keySet(),存储键的Set集合
Set<String> javaSet = javaMap.keySet();
//迭代器遍历Set集合
Iterator<String> javaIt = javaSet.iterator();
while(javaIt.hasNext()) {
//取出Set集合元素,是javaMap集合的键,阶段名字
String javaMapKey = javaIt.next();
//取出javaMap学科集合的值,值是个阶段的Map集合
Map<String, String> jieDuanMap = javaMap.get(javaMapKey);
//遍历阶段的Map集合, 调用方法keySet()拿出阶段Map集合的键
Set<String> jieDuanSet = jieDuanMap.keySet();
//迭代器遍历Set集合
Iterator<String> jieDuanIt = jieDuanSet.iterator();
while(jieDuanIt.hasNext()) {
//取出Set集合的元素,是阶段Map集合的键,学号
String key = jieDuanIt.next();
//取出阶段集合的值,姓名
String value = jieDuanMap.get(key);
System.out.println(javaMapKey+"=="+key+"=="+value);
}
}
}
### 练习三 : 斗地主排序
原理 : 需要自定义顺序
顺序 : 333344445555…AAAA2222王王
自定义顺序的思想 : 编号思想 0123…53 (数字的自然顺序)
每一个牌(字符串)和编号进行对应, 键值对思想实现. 编号为键,牌为值
public class Poker {
public static void main(String[] args) {
Map<Integer, String> pokerMap = new HashMap<Integer, String>();
List<Integer> pokerList = new ArrayList<Integer>();
int index = 0;
String[] colors = {"♥","♠","♦","♣"};
String[] numbers = {"3","4","5","6","7","8","9","10","J","Q","K","A","2"};
for(String number : numbers) {
for(String color : colors) {
pokerMap.put(index, color+number);
pokerList.add(index);
index++;
}
}
pokerMap.put(52, "大王");
pokerMap.put(53, "小王");
pokerList.add(52);
pokerList.add(53);
Collections.shuffle(pokerList);
List<Integer> player1 = new ArrayList<Integer>();
List<Integer> player2 = new ArrayList<Integer>();
List<Integer> player3 = new ArrayList<Integer>();
List<Integer> bottom = new ArrayList<Integer>();
for(int i = 0 ; i < pokerList.size() ; i++) {
if(i < 3) {
bottom.add( pokerList.get(i) );
}
else if( i % 3 == 0) {
player1.add( pokerList.get(i));
}
else if (i % 3 == 1) {
player2.add( pokerList.get(i));
}
else if (i % 3 == 2) {
player3.add( pokerList.get(i));
}
}
Collections.sort(player1);
Collections.sort(player2);
Collections.sort(player3);
Collections.sort(bottom);
look("aaa",pokerMap,player1);
look("bbb",pokerMap,player2);
look("ccc",pokerMap,player3);
look("ddd",pokerMap,bottom);
}
public static void look(String name,Map<Integer,String> map, List<Integer> list) {
System.out.print(name+":");
for(Integer key : list) {
String value = map.get(key);
System.out.print(value+" ");
}
System.out.println();
}
}