1,创建一个类Queue,代表队列(特点:先进先出),添加add(Object obj)及get()方法,mian()方法验证。
package com.bdqn.demo; import java.util.ArrayList; import java.util.LinkedList; import java.util.List; import java.util.NoSuchElementException; public class Queue { private List<Object> arrayList = new ArrayList<Object>(); private LinkedList<Object> linkedList = new LinkedList<Object>(); //ArrayList实现的先进先出 public void arrayListAdd(Object obj) { this.arrayList.add(obj); } public Object arrayListGet() { Object obj = null; if (this.arrayList.size() > 0) { obj = this.arrayList.get(0); this.arrayList.remove(0); } return obj; } //LinkedList实现的先进先出 public void linkedListAdd(Object obj) { this.linkedList.addFirst(obj); } @SuppressWarnings("finally") public Object linkedListGet(){ Object obj = null; try { obj = this.linkedList.getLast(); this.linkedList.removeLast(); } catch (NoSuchElementException e) { }finally{ return obj; } } public static void main(String[] args) { Queue queue = new Queue(); //测试ArrayList,添加0 1 2进去 for (int i = 0; i < 3; i++){ System.out.println("arrayListAdd("+i+")"); queue.arrayListAdd(i); } //输出4次,第4次应该为null,输出顺序和放入顺序一致 for (int i = 0; i < 4; i++) { System.out.println("arrayListGet()=="+queue.arrayListGet()); } //测试Linkedlist,添加0 1 2进去 for (int i = 0; i < 3; i++){ System.out.println("linkedListAdd("+i+")"); queue.linkedListAdd(i); } //输出4次,第4次应该为null,输出顺序和放入顺序一致 for (int i = 0; i < 4; i++) { System.out.println("linkedListGet()=="+queue.linkedListGet()); } } }2,创建一个HashMap类,添加学员姓名及分数,键为学生姓名,值为分数。从HashMap对象获取并输出,修改一位同学的成绩,再次输出。
package com.bdqn.demo; public class Student { private String name;//学生姓名 private int score;//分数 public Student( String name,int score) {//重载接收参数 this.name=name; this.score=score; } public String getName() {//获取名字 return name; } public int getScore() {//获取分数 return score; } } package com.bdqn.demo; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Set; //测试类 public class Test { public static void main(String[] args) { //学生参数传递 Student stu1=new Student("张三", 99); Student stu2=new Student("李四", 80); Student stu3=new Student("王五", 86); Student stu4=new Student("赵六", 72); Map <String,Student>score=new HashMap<String,Student>();//声明HashMap //添加学生参数集合 score.put(stu1.getName(),stu1); score.put(stu2.getName(),stu2); score.put(stu3.getName(),stu3); score.put(stu4.getName(),stu4); for(String key:score.keySet()) {//foreach打印 System.out.println(key+"\t"+score.get(key).getScore()); } stu4=new Student("赵六",76);//修改一名学生成绩 score.put(stu4.getName(), stu4);//添加修改的数据 System.out.println("修改后的学员成绩如下:");//打印修改后的学生成绩 for(String key:score.keySet()) { System.out.println(key+"\t"+score.get(key).getScore()); } } }