实战if-else 过多详解

1.本文实例代码仅仅是俩个小例子。

package com.example.demo.pattern.ifElse;

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.function.Consumer;
import java.util.function.Function;

/**
 *  如何解决解决类似
 *   1 if (condition1) {
 *  2
 *  3 } else if (condition2) {
 *  4
 *  5 } else if (condition3) {
 *  6
 *  7 } else if (condition4) {
 *  8
 *  9 } else {
 * 10
 * 11 }
 *
 * 1 if (param.equals(value1)) {
 * 2     doAction1(someParams);
 * 3 } else if (param.equals(value2)) {
 * 4     doAction2(someParams);
 * 5 } else if (param.equals(value3)) {
 * 6     doAction3(someParams);
 * 7 }
 * 8
 */
public class SolveIfElseOne {
     //定义结构  属于工厂模式 基于java8 lambda
    private  static final Map<String, Consumer<String>> map=new HashMap<>();
    //用LinkedHashMap 是为了保证有序性
    private  static final Map<Integer, Function<Integer,Double>> map1=new LinkedHashMap<>();
    //初始化数据
    static{
        map.put("1",(param)->{doAction1(param);});
        map.put("2",(param)->{doAction2(param);});
        map.put("3",(param)->{doAction3(param);});

        map1.put(2200,(param)->{return  doAction2200(param);});
        map1.put(2700,(param)->{return doAction2700(param);});
        map1.put(3200,(param)->{return doAction3200(param);});
    }

    /**
     * 未重构前
     */
    public void  handle(String param){
        if (param.equals("1")) {
            doAction1(param);
        } else if (param.equals("2")) {
            doAction2(param);
        } else if (param.equals("3")) {
            doAction3(param);
        }
    }

    public static void  doAction1(String param){
        System.out.println(param);
    }

    public static void  doAction2(String param){
        System.out.println(param);
    }

    public static void  doAction3(String param){
        System.out.println(param);
    }

    //未重构前
    /* 1 if income <= 2200
            2   tax = 0
            3 else if income <= 2700
            4   tax = 0.14 * (income - 2200)
            5 else if income <= 3200
            6   tax = 70 + 0.15 * (income - 2700)
            7 else if income <= 3700
            8   tax = 145 + 0.16 * (income - 3200)
            9 ......
            10 else
            11   tax = 53090 + 0.7 * (income - 102200)*/

    public static double  doAction2200(int income){
        double tax = 0;
        return  tax = 0;
    }

    public static double  doAction2700(int income){
        double tax = tax = 0.14 * (income - 2200);
        return  tax ;
    }

    public static double  doAction3200(int income){
        double  tax = 70 + 0.15 * (income - 2700);
        return  tax;
    }

    //重构后 只需要循环一次即可
     public static double getTax(int income){
        double res=0;
        for(Integer integer:map1.keySet()){
               if(income<=integer) {
                   System.out.println(integer+" ");
                   res=map1.get(integer).apply(income);
                   System.out.println(map1.get(integer).apply(income)+" ");
                   break;
               }
        }
        return res;
     }

    public static void main(String[] args) {
        SolveIfElseOne.map.get("1").accept("1");

        System.out.println(getTax(3200));

    }

}