【设计模式-02】Strategy策略模式及应用场景

一、参考资料

• Java 官方文档

Overview (Java SE 18 & JDK 18)module indexhttps://docs.oracle.com/en/java/javase/18/docs/api/index.html

• Java中使用到的策略模式

Comparator、comparable

Comparator (Java SE 18 & JDK 18)declaration: module: java.base, package: java.util, interface: Comparatorhttps://docs.oracle.com/en/java/javase/18/docs/api/java.base/java/util/Comparator.html

Comparable (Java SE 18 & JDK 18)declaration: module: java.base, package: java.lang, interface: Comparablehttps://docs.oracle.com/en/java/javase/18/docs/api/java.base/java/lang/Comparable.html

二、主要设计思想

三、应用场景

1、Cat.java 对象

/**
 * @description: 猫对象
 * @author: flygo
 * @time: 2022/7/4 11:11
 */
public class Cat {

  private int height, weight;

  public Cat() {}

  public Cat(int weight, int height) {
    this.weight = weight;
    this.height = height;
  }

  public int compareTo(Cat c) {
    if (this.weight < c.weight) return -1;
    else if (this.weight > c.weight) return 1;
    else return 0;
  }

  @Override
  public String toString() {
    return "Cat{" + "height=" + height + ", weight=" + weight + '}';
  }
}

2、Sorter.java 排序类

/**
 * @description: 排序对象
 * @author: flygo
 * @time: 2022/7/4 11:16
 */
public class Sorter {

  public void sort(Cat[] arr) {
    for (int i = 0; i < arr.length - 1; i++) {
      int minPos = i;
      for (int j = i + 1; j < arr.length; j++) {
        minPos = arr[j].compareTo(arr[minPos]) == -1 ? j : minPos;
      }
      swap(arr, i, minPos);
    }
  }

  static void swap(Cat[] arr, int i, int j) {
    Cat temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
  }
}

3、StrategyMain 主类

import java.util.Arrays;

/**
 * @description: 主方法
 * @author: flygo
 * @time: 2022/7/4 11:15
 */
public class StrategyMain {

  public static void main(String[] args) {
    //    int[] arr = {2, 4, 3, 6, 10, 1};

    Cat[] arr = {new Cat(3, 3), new Cat(5, 5), new Cat(1, 1)};
    Sorter sorter = new Sorter();
    sorter.sort(arr);

    System.out.println(Arrays.toString(arr));
  }
}

四、使用泛型调整修改

1、定义Comparable接口

/**
 * @description: 比较接口类
 * @author: flygo
 * @time: 2022/7/4 15:46
 */
public interface Comparable<T> {

  int compareTo(T o);
}

2、Sorter 排序类

/**
 * @description: 排序对象
 * @author: flygo
 * @time: 2022/7/4 11:16
 */
public class Sorter {

  public void sort(Comparable[] arr) {
    for (int i = 0; i < arr.length - 1; i++) {
      int minPos = i;
      for (int j = i + 1; j < arr.length; j++) {
        minPos = arr[j].compareTo(arr[minPos]) == -1 ? j : minPos;
      }
      swap(arr, i, minPos);
    }
  }

  static void swap(Comparable[] arr, int i, int j) {
    Comparable temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
  }
}

3、定义一个需要排序的对象，如Dog

/**
 * @description: 狗
 * @author: flygo
 * @time: 2022/7/4 15:48
 */
public class Dog implements Comparable<Dog> {

  int food;

  public Dog(int food) {
    this.food = food;
  }

  @Override
  public int compareTo(Dog o) {
    if (this.food < o.food) return -1;
    else if (this.food > o.food) return 1;
    else return 0;
  }

  @Override
  public String toString() {
    return "Dog{" + "food=" + food + '}';
  }
}

4、最终效果

import java.util.Arrays;

/**
 * @description: 主方法
 * @author: flygo
 * @time: 2022/7/4 11:15
 */
public class StrategyMain {

  public static void main(String[] args) {
    //    int[] arr = {2, 4, 3, 6, 10, 1};
    //    Cat[] arr = {new Cat(3, 3), new Cat(5, 5), new Cat(1, 1)};

    Dog[] arr = {new Dog(5), new Dog(1), new Dog(3)};

    Sorter sorter = new Sorter();
    sorter.sort(arr);

    System.out.println(Arrays.toString(arr));
  }
}

五、源码地址

GitHub - jxaufang168/Design-Patterns: 设计模式学习设计模式学习. Contribute to jxaufang168/Design-Patterns development by creating an account on GitHub.https://github.com/jxaufang168/Design-Patterns