字符串练习题（三）：句子的逆序

public class Reverse {
    public String reverseSentence(String A, int n) {
        // write code here
        if(n==0||null==A) return A;
        char[] as=A.toCharArray();
        reverseWord(as);
        return String.valueOf(as);
         
    }
    public void reverseWord(char[] chas){
        if (null==chas ||chas.length==0) return;
        reverse(chas,0,chas.length-1);
        int l=-1;
        int r=-1;
        for(int i=0;i<chas.length;i++){
            if(chas[i]!=‘ ‘){
                l=i==0||chas[i-1]==‘ ‘?i:l;
                r=i==chas.length-1||chas[i+1]==‘ ‘?i:r;
            }
            if (l != -1 && r != -1) {
                reverse(chas, l, r);
                l = -1;
                r = -1;
            }
        }
         
    }
    public void reverse(char[] as,int start,int end){
        char temp=0;
        while(start<end){
            temp=as[start];
            as[start]=as[end];
            as[end]=temp;
            start++;
            end--;     
        }
    }
}