kmp算法

 public String GetNext(String c) {
        int i=1;
        int[] next=new int[c.length()];
        next[0]=0;
        int j=0;
        while(i<c.length())
        {
            if(j==0||Character.toString(c.charAt(i-1)).equals(Character.toString(c.charAt(j-1))))
            {++i;
             ++j;
             next[i-1]=j;
            }//if
            else
            j=next[j-1];
        }//while
        String str2="";
        for(int m=0;m<next.length;m++)
    {
        str2=str2+Integer.toString(next[m]);
    }//for

        return str2;

    }