字符串查找之kmp算法

public int[] getNext(String b)
    {
        int len=b.length();
        int j=0;
        int next[]=new int[len+1];//next表示長度爲i的字符串前綴和後綴的最長公共部分，從1開始
        next[0]=next[1]=0;
        for(int i=1;i<len;i++)//i表示字符串的下標，從0開始
        {//j在每次循環開始都表示next[i]的值，同時也表示需要比較的下一個位置
            while(j>0&&b.charAt(i)!=b.charAt(j))j=next[j];
            if(b.charAt(i)==b.charAt(j))j++;
            next[i+1]=j;
        }
        return next;
    }
    public void search(String original, String find, int next[]) {
        int j = 0;
        for (int i = 0; i < original.length(); i++) {
            while (j > 0 && original.charAt(i) != find.charAt(j))
                j = next[j];
            if (original.charAt(i) == find.charAt(j))
                j++;
            if (j == find.length()) {
                System.out.println("find at position " + (i - j));
                System.out.println(original.subSequence(i - j + 1, i + 1));
                j = next[j];
            }
        }
    }

    public static void main(String[] args) {
        String s1 = "BC ABCDAB ABCDABCDABDE";
        String s2 = "ABCDABD";
        Kmp kmp = new Kmp();
        int[] next = kmp.getNext(s2);
        System.out.println(Arrays.toString(next));
        kmp.search(s1,s2,next);
    }