java Map集合练习

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import java.util.Comparator;import java.util.HashMap;import java.util.Iterator;import java.util.Map;import java.util.Set;import java.util.TreeMap;public class MapDemo {public static void main(String[] args) {//HashMethod();TreeMethod();}/* * TreeMap中的元素可以排列顺序，构造时用比较器或者实现Comparable接口 */private static void TreeMethod() {Map<Student1,String> map = new TreeMap<Student1,String>(new StuNamComp());map.put(new Student1("acc",10),"beijing");map.put(new Student1("aaa",12),"wuhan");map.put(new Student1("abc",14),"shanghai");Set<Student1> keySet = map.keySet();for(Iterator<Student1> it = keySet.iterator();it.hasNext();) {Student1 stu = it.next();System.out.println(stu + map.get(stu));}System.out.println("==============================");Set<Map.Entry<Student1, String>> entrySet = map.entrySet();for(Iterator<Map.Entry<Student1, String>> it = entrySet.iterator();it.hasNext();) {Map.Entry<Student1, String> me = it.next();System.out.println(me.getKey() + me.getValue());}}/* * HashMap中的元素无序(存入和指定的位置不保证一致)，按照哈希表存储 */private static void HashMethod() {Map<Student1,String> map = new HashMap<Student1,String>();map.put(new Student1("zhangsan",10),"beijing");map.put(new Student1("lisi",12),"wuhan");map.put(new Student1("wangwu",14),"shanghai");Set<Student1> keySet = map.keySet();for(Iterator<Student1> it = keySet.iterator();it.hasNext();) {Student1 stu = it.next();System.out.println(stu + map.get(stu));}System.out.println("==============================");Set<Map.Entry<Student1, String>> entrySet = map.entrySet();for(Iterator<Map.Entry<Student1, String>> it = entrySet.iterator();it.hasNext();) {Map.Entry<Student1, String> me = it.next();System.out.println(me.getKey() + me.getValue());}}}class StuNamComp implements Comparator<Student1> {@Overridepublic int compare(Student1 o1, Student1 o2) {int num = o1.name.compareTo(o2.name);if(num == 0)return new Integer(o1.age).compareTo(new Integer(o2.age));return num;}}class Student1 implements Comparable<Student1>{String name;int age;Student1(String name,int age) {this.name = name;this.age = age;}@Overridepublic int hashCode() {return this.name.hashCode() * this.age * 20;}@Overridepublic boolean equals(Object obj) {if(!(obj instanceof Student1)) {throw new ClassCastException("类型错误");}Student1 stu = (Student1) obj;return this.name.equals(stu.name) && this.age == stu.age;}@Overridepublic String toString() {return this.name + ".." + age;}@Overridepublic int compareTo(Student1 o) {int num = new Integer(this.age).compareTo(new Integer(o.age));if(num == 0) {return this.name.compareTo(o.name);}return num;}}
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