Java每日算法

分析

模板函数，泛型参数传递排序

·针对各种参数，甚至自定义参数进行排序
·使用Comparable处理所有参数

编码

@Data
public class Student implements Comparable<Student> {private String name;private int score;public Student(String name, int score) {this.name = name;this.score = score;}/*** 定义Student的compareTo函数，如果分数相等，则按照名字的字母序排序* 如果分数不等，则分数高的靠前* @param o* @return*/@Overridepublic int compareTo(Student o) {if (this.score < o.score){return -1;}else if(this.score > o.score){return 1;}else{return this.name.compareTo(o.name);}}/*** 定义Student实例的打印输出方式* @return*/@Overridepublic String toString() {return "Student: " + this.name + " " + Integer.toString( this.score );}}

模板化选择排序

public class SelectionSort {private SelectionSort(){}public static void sort(Comparable[] arr){for (int i = 0;i<arr.length;i++){int minIndex = i;for (int j=i+1;j<arr.length;j++){if (arr[j].compareTo(arr[minIndex]) < 0){minIndex = j;}}swap(arr,i,minIndex);}}private static void swap(Object[] arr, int i, int j) {Object t = arr[i];arr[i] = arr[j];arr[j] = t;}public static void main(String[] args) {// 测试IntegerInteger[] a = {10,9,8,7,6,5,4,3,2,1};SelectionSort.sort(a);for( int i = 0 ; i < a.length ; i ++ ){System.out.print(a[i]);System.out.print(' ');}System.out.println();// 测试DoubleDouble[] b = {4.4, 3.3, 2.2, 1.1};SelectionSort.sort(b);for( int i = 0 ; i < b.length ; i ++ ){System.out.print(b[i]);System.out.print(' ');}System.out.println();// 测试StringString[] c = {"D", "C", "B", "A"};SelectionSort.sort(c);for( int i = 0 ; i < c.length ; i ++ ){System.out.print(c[i]);System.out.print(' ');}System.out.println();// 测试自定义的类 StudentStudent[] d = new Student[4];d[0] = new Student("D",90);d[1] = new Student("C",100);d[2] = new Student("B",95);d[3] = new Student("A",95);SelectionSort.sort(d);for( int i = 0 ; i < d.length ; i ++ )System.out.println(d[i]);}}