问题为将类似*"Hello      world!"*变成"Hello world!" 问题思路:先切割字符串,再将字符串重新组合 核心代码

public  void filter(String s){
        String[] b = s.split("\\s+");
        StringBuffer stringBuffer = new StringBuffer();
        for(String c:b){
            stringBuffer.append(" "+c);
        }
        System.out.print(stringBuffer.toString());


    }