集合案例
一：键盘录入学生案列（TreeMap）
熟练运用TreeMap的排序方式：
需求：键盘录入5个学生信息，并按总成绩从大到小的顺序排序
1.创建一个标准的学生类
package com.edu01;
public class Student implements Comparable<Student>{
private String name;
private int chinese;
private int math;
private int english;
private int allScore;
public Student() {
super();
// TODO Auto-generated constructor stub
}
public Student(String name, int chinese, int math, int english, int allScore) {
super();
this.name = name;
this.chinese = chinese;
this.math = math;
this.english = english;
this.allScore = allScore;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getChinese() {
return chinese;
}
public void setChinese(int chinese) {
this.chinese = chinese;
}
public int getMath() {
return math;
}
public void setMath(int math) {
this.math = math;
}
public int getEnglish() {
return english;
}
public void setEnglish(int english) {
this.english = english;
}
public int getAllScore(){
return chinese + math + english;
}
@Override
public int compareTo(Student s) {
// TODO Auto-generated method stub
int num = this.getAllScore() - s.getAllScore();
int num2 = num==0?this.name.compareTo(s.name):num;
return num2;
}
}
package com.edu01;
import java.util.Scanner;
import java.util.TreeSet;
public class Test {
public static void main(String[] args) {
//4:键盘录入5个学生信息(姓名,语文成绩,数学成绩,英语成绩),按照总分从高到低输出到控制台
//创建一个TreeSet集合
TreeSet<Student> ts = new TreeSet<Student>();
for (int i = 0; i < 5; i++) {
Scanner sc = new Scanner(System.in);
System.out.println("请输入你的姓名");
String name = sc.nextLine();
System.out.println("请输入你的语文成绩");
int chinese = sc. nextInt();
System.out.println("请输入你的数学成绩");
int math = sc.nextInt();
System.out.println("请输入你的英语成绩");
int english = sc.nextInt();
//将上面所有信息封装成一个对象
int allScore = chinese+math+english;
//创建学生对象
Student s = new Student(name, chinese, math, english, allScore);
ts.add(s);
}
//遍历集合
for (Student s : ts) {
System.out.println(s.getName()+" "+s.getAllScore());
}
}
}
二. 斗地主案例
1.熟悉List集合，完成斗地主案例：
package com.edu03;
import java.util.ArrayList;
import java.util.Collections;
public class Poker {
public static void main(String[] args) {
//创建牌盒
ArrayList<String> al = new ArrayList<String>();
String []colors = {"梅花","方片","红桃","黑桃"};
String []numbers = {"3","4","5","6","7","8","9","10","J","Q","K","A","2"};
for (String c : colors) {
for (String n : numbers) {
al.add(c+n);
}
}
al.add("小王");
al.add("大王");
Collections.shuffle(al);
ArrayList<String> zhangsan = new ArrayList<String>();
ArrayList<String> lisi = new ArrayList<String>();
ArrayList<String> wangwu = new ArrayList<>();
ArrayList<String> dipai = new ArrayList<>();
//发牌
for (int i = 0; i < al.size(); i++) {
if(i>=al.size()-3){
dipai.add(al.get(i));
}else if(i%3==0){
zhangsan.add(al.get(i));
}else if(i%3==1){
lisi.add(al.get(i));
}else if(i%3==2){
wangwu.add(al.get(i));
}
}
lookpoker("张三",zhangsan);
lookpoker("李四",lisi);
lookpoker("王五",wangwu);
lookpoker("底牌",dipai);
}
private static void lookpoker(String string, ArrayList<String> al) {
// TODO Auto-generated method stub
System.out.println(string+"的牌是：");
for (String string2 : al) {
System.out.print(string2+" ");
}
System.out.println();
}
}
2.由于TreeMap集合低层机构为二叉树结构，所以我们可以利用TreeMap集合的有序性来改进上面的程序：
package com.edu03;
import java.util.ArrayList;
import java.util.Collections;
import java.util.TreeMap;
import java.util.TreeSet;
public class PokerDemo2 {
public static void main(String[] args) {
//利用TreeMap集合
TreeMap<Integer, String> tm = new TreeMap<Integer,String>();
String []colors = {"红桃","黑桃","方片","梅花",};
String []numbers = {"3","4","5","6","7","8","9","10","J","Q","K","A","2"};
ArrayList<Integer> list = new ArrayList<Integer>();
int index= 0;
for (String string : numbers) {
for (String c : colors) {
tm.put(index, string+c);
list.add(index);
index++;
}
}
tm.put(index, "小王");
list.add(index);
index++;
tm.put(index,"大王" );
list.add(index);
Collections.shuffle(list);
//由于每个个人的拍都要排好序，所以我们选择TreeSet集合
TreeSet<Integer> zhangsan = new TreeSet<Integer>();
TreeSet<Integer> lisi = new TreeSet<Integer>();
TreeSet<Integer> wangwu = new TreeSet<Integer>();
TreeSet<Integer> dipai = new TreeSet<Integer>();
//发牌
for (int i = 0; i < list.size(); i++) {
if(i>= list.size()-3){
dipai.add(list.get(i));
}else if(i%3==0){
zhangsan.add(list.get(i));
}else if(i%3==1){
lisi.add(list.get(i));
}else if(i%3==2){
wangwu.add(list.get(i));
}
}
lookpoker("张三",zhangsan,tm);
lookpoker("李四",lisi,tm);
lookpoker("王五",wangwu,tm);
lookpoker("底牌",dipai,tm);
}
private static void lookpoker(String string, TreeSet<Integer> list,
TreeMap<Integer, String> tm) {
// TODO Auto-generated method stub
System.out.println(string+"的牌是：");
for (Integer integer : list) {
System.out.print(tm.get(integer)+" ");
}
System.out.println();
}
}
