day26-6String repalce(String old, String newstr): 将字符串中的老字符串,替换为新字符串

public static void main(String[] args){
fu5();
}

public static void fu5(){
String a="aaa222222";
System.out.print("原函数"+a+" ");
String a1=a.replace('2','3');
System.out.println("修改后"+a1);
}