学生类Student.java
import lombok.Data;
public class Student {
private String name;
private int height;
private String rank;
public Student(){}
public Student(String n,int h){
name=n;
height=h;
}
public Student(String n,int h,String r){
name=n;
height=h;
rank=r;
}
public void setRank(String rank) {
this.rank=rank;
}
public int getHeight() {
return height;
}
public String getRank() {
return rank;
}
public String toString() { //以文本方式表示
return "Student(name="+name+",height="+height+",rank="+rank+")";
}
}
主程序Knn01.java
import java.util.ArrayList;
import java.util.List;
public class Knn01 {
public static List<Student> dataList =new ArrayList<>(); //定义初始数据集
public static void main(String[] args) {
long startTime = System.currentTimeMillis();
initData();
Student a=new Student("姐姐",175);
int k=6;
Student student=Knn(a,k);
System.out.println("输入的学生数据： "+student);
long endTime = System.currentTimeMillis();
System.out.println("此次运行共耗时： " +(endTime-startTime)/1000.0+"s");
}
/*找出同等级占比最多的学生等级*/
public static String getCategoryStudent(List<Student> categoryList){
int tallCount = 0;
int midCount = 0;
int smallCount = 0;
for (Student b : categoryList) {
if (b.getRank().equals("高")) tallCount++;
else if (b.getRank().equals("中等")) midCount++;
else smallCount++;
}
int max;
max = Math.max(tallCount, midCount);
max = Math.max(smallCount, max);
if (smallCount == max) return "矮";
else if (tallCount == max) return "高";
else return "中等";
}
/*计算出a距离categoryList集合中最远的学生对象*/
public static Student getCalculate(Student a, List<Student> categoryList) {
int maxHeight = 0; //存放a与类别集合categoryList的最远距离
Student resultStu = new Student(); //存放要返回的学生，即a与类别集合categoryList距离最远的学生
for (Student b : categoryList) {
int ab = Math.abs(a.getHeight() - b.getHeight()); //a与b的距离
if (ab > maxHeight){ //a与b的距离大于maxHeight，则对maxHeight和resultStu进行更新
maxHeight = ab;
resultStu = b;
}
}
return resultStu;
}
/*对输入学生类进行Knn算法实例化该学生的等级后，将该学生返回*/
public static Student Knn(Student a,int k){
ArrayList<Student> categoryList = new ArrayList<>(); //存放距离a最近的k个学生，最初存放数据集的前k项
for (int i = 0; i < dataList.size(); i++) {
if (i < k) categoryList.add(dataList.get(i));
else {
//遍历数据集dataList，计算a距离从数据集的第6项开始的每一项的距离ad
int ad = Math.abs(a.getHeight() - dataList.get(i).getHeight());
//另外调用getCalculate()方法计算出a距离categoryList集合中最远的学生对象b
Student b = getCalculate(a, categoryList); //存放a距离类别集合中最远的学生
int c = Math.abs(b.getHeight() - a.getHeight());
if (c > ad){//若b距离a的身高距离c大于ad，则在categoryList中去除掉b
categoryList.remove(b); //在集合列表中去除b
categoryList.add(dataList.get(i));//将数据集中的该项加入到categoryList集合中来
}
}
}
System.out.println("最近的"+k+"位学生：");
for(Student temp:categoryList){
System.out.println(temp);
}
String rank = getCategoryStudent(categoryList);
a.setRank(rank);
return a;
}
/*初始化数据*/
public static void initData(){
Student s1 = new Student("李丽", 150, "矮");
Student s2 = new Student("吉米", 192, "高");
Student s3 = new Student("马大华", 170, "中等");
Student s4 = new Student("王晓华", 173, "中等");
Student s5 = new Student("刘敏", 160, "矮");
Student s6 = new Student("张强", 175, "中等");
Student s7 = new Student("李秦", 160, "矮");
Student s8 = new Student("王壮", 190, "高");
Student s9 = new Student("刘冰", 168, "中等");
Student s10 = new Student("张喆", 178, "中等");
Student s11 = new Student("杨毅", 170, "中等");
Student s12 = new Student("徐田", 168, "中等");
Student s13 = new Student("高杰", 165, "矮");
Student s14 = new Student("张晓", 178, "中等");
Student s15 = new Student("德一", 191, "高");
dataList.add(s1);
dataList.add(s2);
dataList.add(s3);
dataList.add(s4);
dataList.add(s5);
dataList.add(s6);
dataList.add(s7);
dataList.add(s8);
dataList.add(s9);
dataList.add(s10);
dataList.add(s11);
dataList.add(s12);
dataList.add(s13);
dataList.add(s14);
dataList.add(s15);
}
}
实在没有什么头绪，主要是把主函数的方法Knn内部的“遍历数据集dataList，计算a距离从数据集的第k项开始的每一项的距离ad”改成同时执行
/*对输入学生类进行Knn算法实例化该学生的等级后，将该学生返回*/
public static Student Knn(Student a,int k){
ArrayList<Student> categoryList = new ArrayList<>(); //存放距离a最近的k个学生，最初存放数据集的前k项
for (int i = 0; i < dataList.size(); i++) {
if (i < k) categoryList.add(dataList.get(i));
else {
//遍历数据集dataList，计算a距离从数据集的第6项开始的每一项的距离ad
int ad = Math.abs(a.getHeight() - dataList.get(i).getHeight());
//另外调用getCalculate()方法计算出a距离categoryList集合中最远的学生对象b
Student b = getCalculate(a, categoryList); //存放a距离类别集合中最远的学生
int c = Math.abs(b.getHeight() - a.getHeight());
if (c > ad){//若b距离a的身高距离c大于ad，则在categoryList中去除掉b
categoryList.remove(b); //在集合列表中去除b
categoryList.add(dataList.get(i));//将数据集中的该项加入到categoryList集合中来
}
}
}
System.out.println("最近的"+k+"位学生：");
for(Student temp:categoryList){
System.out.println(temp);
}
String rank = getCategoryStudent(categoryList);
a.setRank(rank);
return a;
}
你需要的是掌握Java并行计算的例子：
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class ParallelCount {
public static void main(String[] args) throws InterruptedException {
int[] nums = {1, 3, 5, 7, 9};
int threads = 3;
ExecutorService executor = Executors.newFixedThreadPool(threads);
CountDownLatch latch = new CountDownLatch(threads);
int blockSize = nums.length / threads;
for (int i = 0; i < threads; i++) {
int start = i * blockSize;
int end = (i == threads - 1) ? nums.length : (i + 1) * blockSize;
executor.submit(new SumTask(nums, start, end, latch));
}
latch.await();
System.out.println("Done!");
executor.shutdown();
}
static class SumTask implements Runnable {
private int[] nums;
private int start;
private int end;
private CountDownLatch latch;
public SumTask(int[] nums, int start, int end, CountDownLatch latch) {
this.nums = nums;
this.start = start;
this.end = end;
this.latch = latch;
}
@Override
public void run() {
int sum = 0;
for (int i = start; i < end; i++) {
sum += nums[i];
}
System.out.println(Thread.currentThread().getName() + ": " + sum);
latch.countDown();
}
}
}