JAVA集合类（3）：Set集合
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Eclipse提供了快捷重写equals与hashCode的方法：在Source工具栏中提供了快捷方法：
package com.test.array;import java.util.HashSet;public class HashTest {public static void main(String[] args) {HashSet set = new HashSet();set.add(new Person("lisi"));set.add(new Person("lisi"));System.out.println(set);}}class Person{String name;public Person(String name){this.name = name;}public int hashCode() {return this.name.hashCode();}public boolean equals(Object obj) {if(this == obj){return true;}if(obj != null && obj instanceof Person){Person p = (Person)obj;if(name.equals(p.name)){return true;}}return false;}}?
结果只打印出了一个对象
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package com.test.array;import java.util.HashSet;import java.util.Iterator;public class IteratorTest {public static void main(String[] args) {HashSet set = new HashSet();set.add("a");set.add("b");set.add("c");set.add("d");set.add("e");Iterator iter = set.iterator();while(iter.hasNext()){String value = (String)iter.next();System.out.println(value);}}}也可使用for循环迭代
for(Iterator iter = set.iterator();iter.hasNext();){String value = (String)iter.next();System.out.println(value);}??
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下例中的TreeSet必须要有一个comparator类，才能往里添加Student对象，否则会抛出ClassCastException
package com.test.array;import java.util.Comparator;import java.util.TreeSet;public class TreeSetTest {public static void main(String[] args) {TreeSet set = new TreeSet(new StudentComparator());set.add(new Student(80));set.add(new Student(90));set.add(new Student(60));set.add(new Student(70));System.out.println(set);}}class Student{int score;public Student(int score) {this.score = score;}public String toString() {return String.valueOf(score);}}class StudentComparator implements Comparator{//按学生成绩升序 public int compare(Object o1, Object o2) {Student s1 =(Student)o1;Student s2 =(Student)o2;return s1.score - s2.score;}}?
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