react hooks方法获取不到最新的state解决方法

问题

在setState方法执行之后，再执行自定义的方法，这个自定义方法里面获取不到最新的state状态

import React, {
          
   useState} from "react";
import {
          
    Button } from "antd"

const Demo = () => {
          
   
    const [num, changeNum] = useState(1)
    const [str, changeStr] = useState("现在数字是1")

    const getNum = () => {
          
   
        const newStr = "现在数字是" + num
        console.log(newStr)
        changeStr(newStr)
    }

    const setNum = () => {
          
   
    	// 使用 async await  自执行函数  setTimeout 都没用
        changeNum(num + 1)
        // 执行之后  getNum里拿不到最新的state
        getNum()
    }

    return (
        <div>
            <Button onClick={
          
   setNum}>点我+1</Button>
            <div>{
          
   num}</div>
            <div>{
          
   str}</div>
        </div>
    )
}

export default Demo

解决

1. 第一种

通过useEffect方法监听num 再去触发getNum函数

useEffect(() => {
          
   
        getNum()
    }, [num])

    const getNum = () => {
          
   
        const newStr = "现在数字是" + num
        changeStr(newStr)
    }
    
    const setNum = () => {
          
   
        changeNum(num + 1)
    }

2. 第二种

const numRef = useRef(1)
   const [num, changeNum] = useState(numRef.current)
   const [str, changeStr] = useState("现在数字是1")

   const getNum = () => {
          
   
       const newStr = "现在数字是" + numRef.current
       changeStr(newStr)
   }

   const setNum = () => {
          
   
       numRef.current = num + 1
       changeNum(numRef.current)
       getNum()
   }

完整第一种代码

import React, {
          
   useState, useEffect} from "react";
import {
          
    Button } from "antd"

const Demo = () => {
          
   
    const [num, changeNum] = useState(1)
    const [str, changeStr] = useState("现在数字是1")

    useEffect(() => {
          
   
        getNum()
    }, [num])

    const getNum = () => {
          
   
        const newStr = "现在数字是" + num
        changeStr(newStr)
    }

    const setNum = () => {
          
   
        changeNum(num + 1)
    }

    return (
      <div>
          <Button onClick={
          
   setNum}>点我+1</Button>
          <div>{
          
   num}</div>
          <div>{
          
   str}</div>
      </div>
    )
}

export default Demo

完整第二种代码

import React, {
          
   useState, useEffect, useRef} from "react";
import {
          
    Button } from "antd"

const Demo = () => {
          
   
    const numRef = useRef(1)
    const [num, changeNum] = useState(numRef.current)
    const [str, changeStr] = useState("现在数字是1")

    const getNum = () => {
          
   
        const newStr = "现在数字是" + numRef.current
        changeStr(newStr)
    }

    const setNum = () => {
          
   
        numRef.current = num + 1
        changeNum(numRef.current)
        getNum()
    }

    return (
      <div>
          <Button onClick={
          
   setNum}>点我+1</Button>
          <div>{
          
   num}</div>
          <div>{
          
   str}</div>
      </div>
    )
}

export default Demo