java106-字符串tocharArray，tolowercase，touppercase方法

public class test45 {
     //将给定的字符串返回成一个数组
     public static char[] toArrayFromString(String target){
         return target.toCharArray();
     }
     //大小写转换根据所给的第二个参数取决于大小写转换
     public  static String toLowerUpper(char[] chs,char ch){
         if(ch=='l'||ch=='L')
             return new String(chs).toLowerCase();
             return new String(chs).toUpperCase();
  
     }
 }

测试

public class test46 {
     public  static void main(String[] args){
         String target="歌谣,小白,小红,小花,小草,小黑";
         char[] chs={'a','f','F','d','d','F','G','R','R','u'};
         System.out.println(test45.toLowerUpper(chs,'l'));
         //替换字符
         System.out.println(target.replace(',',' '));
     }
 }

运行结果