IO流加集合加强练习题附答案(5)

}

public void setName(String name) { this.name = name; }

public int getAge() { return age; }

public void setAge(int age) { this.age = age; }

public void show() {

System.out.println(\ + this.name + \

+ this.age +\); } }

class Undergraduate extends Student { private String degree;

public Undergraduate(String degree) {

super(); }

public Undergraduate() { super(); }

public Undergraduate(String name, int age, String degree) {

super(name, age); this.degree = degree; }

@Override

public void show() {

System.out.println(\ + this.getName() + \

+ this.getAge() + \学科=\ + this.degree + \); } }

题目十:在HashSet集合中添加三个Person对象，把姓名相同的人当作同一个人，

禁止重复添加。 添加完成后以两种遍历方式遍历输出.

import java.util.HashSet; import java.util.Iterator; public class Demo7 {

public static void main(String[] args) {

HashSet hashSet=new HashSet(); hashSet.add(new Person(\张三\, 26)); hashSet.add(new Person(\李四\, 25)); hashSet.add(new Person(\王武\, 23)); hashSet.add(new Person(\张气\, 28)); hashSet.add(new Person(\张三\, 31)); hashSet.add(new Person(\李四\, 22)); //增强for遍历输出

for (Person person : hashSet) { System.out.println(person); }

//迭代器遍历输出

Iterator it =hashSet.iterator(); while(it.hasNext()){

System.out.println(it.next()); } }

}

class Person{

private String name; private int age; public Person() { super(); }

public Person(String name, int age) { super();

this.name = name; this.age = age; }

public String getName() { return name; }

public void setName(String name) { this.name = name; }

public int getAge() { return age; }

public void setAge(int age) {

this.age = age; }

@Override

public String toString() {

return \[name=\ + name + \age=\ + age + \; }

@Override

public int hashCode() {

return this.name.hashCode(); }

@Override

public boolean equals(Object obj) { Person p=(Person) obj;

return this.name.equals(p.name); } }

题目十一:选择合适的Map集合保存5位学员的学号和姓名，然后按学号的自然顺序的倒序将这些键值对一一打印出来(要求使用两种遍历方式)。

import java.util.Comparator; import java.util.Map; import java.util.Map.Entry; import java.util.TreeMap; public class Demo8 {