排序之简单排序

package cn.silentcow.comparable;

/**
 * 学生类
 * @author silentCow
 * @Date 2020/8/9 8:44
 */
public class Student implements Comparable<Student>{

    private int age;
    private String name;

    public Student(int age, String name) {
        this.age = age;
        this.name = name;
    }

    public Student() {
    }

    public int getAge() {
        return age;
    }

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

    public String getName() {
        return name;
    }

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

    @Override
    public String toString() {
        return "Student{" +
                "age=" + age +
                ", name='" + name + '\'' +
                '}';
    }

    /**
     * 定义比较规则
     * @param o
     * @return
     */
    @Override
    public int compareTo(Student o) {
        return this.getAge() - o.getAge();
    }
}

package cn.silentcow.comparable;

/**
 * 测试类
 * @author silentCow
 * @Date 2020/8/9 8:45
 */
public class StudentTest {

    public static void main(String[] args) {
        // 创建Student对象，并调用getMax方法，进行测试
        Student stu1 = new Student(15, "张三");
        Student stu2 = new Student(16, "李四");

        Comparable max = getMax(stu1, stu2);
        System.out.println(max);
    }

    public static Comparable getMax(Comparable c1,Comparable c2) {
        int result = c1.compareTo(c2);
        // 如果 result < 0,则 c1 比 c2 小;
        // 如果 result = 0,则 c1 和 c2 相等;
        // 如果 result > 0,则 c1 比 c2 大;
        if (result >= 0) {
            return c1;
        } else {
            return c2;
        }
    }

}

package cn.silentcow.comparable;

/**
 * @author silentCow
 * @Date 2020/8/9 9:11
 */
public class Bubble {

    //对数组a中的元素进行排序
    public static void sort(Comparable[] a) {
        for (int i = a.length - 1; i > 0; i--) {
            for (int j = 0; j < i; j++) {
                if (greater(a[j], a[j + 1])) {
                    exch(a, j, j + 1);
                }
            }
        }
    }


    //比较v元素是否大于w元素
    private static boolean greater(Comparable v, Comparable w) {
        return v.compareTo(w) > 0;
    }

    // 数组元素i和j交换位置
    private static void exch(Comparable[] a, int i, int j) {
        Comparable t = a[i];
        a[i] = a[j];
        a[j] = t;
    }

}

package cn.silentcow.test;

import cn.silentcow.comparable.Bubble;

import java.util.Arrays;

/**
 * @author silentCow
 * @Date 2020/8/9 9:14
 */
public class SortTest {
    public static void main(String[] args) {
        Integer[] a = {4, 5, 6, 3, 2, 1};
        Bubble.sort(a);
        System.out.println(Arrays.toString(a));
    }
}

package cn.silentcow.comparable;

/**
 * @author silentCow
 * @Date 2020/8/9 12:34
 */
public class Selection {

    //对数组a中的元素进行排序
    public static void sort(Comparable[] a) {
        for (int i = 0; i <= a.length - 2; i++) {
            //假定本次遍历，最小值所在的索引是i
            int minIndex = i;
            for (int j = i + 1; j < a.length; j++) {
                if (greater(a[minIndex], a[j])) {
                    //跟换最小值所在的索引
                    minIndex=j;
                }
            }
            //交换i索引处和minIndex索引处的值
            exch(a, i, minIndex);
        }
    }

    //比较v元素是否大于w元素
    private static boolean greater(Comparable v, Comparable w) {
        return v.compareTo(w) > 0;
    }

    //数组元素i和j交换位置
    private static void exch(Comparable[] a, int i, int j) {
        Comparable t = a[i];
        a[i] = a[j];
        a[j] = t;
    }
}

package cn.silentcow.test;

import cn.silentcow.comparable.Selection;

import java.util.Arrays;

/**
 * @author silentCow
 * @Date 2020/8/9 12:35
 */
public class SelectionTest {

    public static void main(String[] args) {
        Integer[] a = {4, 6, 8, 7, 9, 2, 10, 1};
        Selection.sort(a);
        System.out.println(Arrays.toString(a));
    }

}

package cn.silentcow.comparable;

/**
 * @author silentCow
 * @Date 2020/8/9 15:08
 */
public class Insertion {

    // 对数组a中的元素进行排序
    public static void sort(Comparable[] a) {

        for (int i = 0; i < a.length; i++) {
            //当前元素为a[i],依次和i前面的元素比较，找到一个小于等于a[i]的元素
            for (int j = i; j > 0; j--) {
                if (greater(a[j - 1], a[j])) {
                    // 交换元素
                    exch(a, j - 1, j);
                } else {
                    // 找到了该元素，结束
                    break;
                }
            }
        }

    }

    //比较v元素是否大于w元素
    private static boolean greater(Comparable v, Comparable w) {
        return v.compareTo(w) > 0;
    }

    // 数组元素i和j交换位置
    private static void exch(Comparable[] a, int i, int j) {
        Comparable t = a[i];
        a[i] = a[j];
        a[j] = t;
    }

}

package cn.silentcow.test;

import cn.silentcow.comparable.Insertion;

import java.util.Arrays;

/**
 * @author silentCow
 * @Date 2020/8/9 15:08
 */
public class InsertionTest {
    public static void main(String[] args) {
        Integer[] arr = {4, 3, 2, 10, 12, 1, 5, 6};
        Insertion.sort(arr);
        System.out.println(Arrays.toString(arr));
    }
}