KMP算法的java实现

写的很菜，理解的不是很深刻！贴出来共勉吧！！
先来几个大神的连接
大神一

大神二

public class Main {

    private static String par;
    private static String ori;

    public static void main(String[] args) {
        ori = "BBC ABCDABD ABCD E";// 原串
        par = "ABCDABD";// 模式串
        char[] s = ori.toCharArray();
        char[] t = par.toCharArray();
        System.out.println(KMP_Index(s, t));
    }

    private static int KMP_Index(char[] s, char[] t) {
        // TODO Auto-generated method stub
        int[] next = next(t);
        int i = 0;
        int j = 0;
        while (i <= s.length - 1 && j <= t.length - 1) {
            if (j == -1 || s[i] == t[j]) {
                i++;
                j++;
            } else {
                j = next[j];
            }
        }
        if (j < t.length) {
            return -1;
        } else {
            return i - t.length;
        }
    }

    private static int[] next(char[] t) {//获取模式串的next数组
        // TODO Auto-generated method stub
        int next[] = new int[t.length];
        next[0] = -1;
        int i = 0;
        int j = -1;
        while (i < t.length - 1) {
            if (j == -1 || t[i] == t[j]) {
                i++;
                j++;
                if (t[i] != t[j]) {
                    next[i] = j;
                } else {
                    next[i] = next[j];
                }
            } else {
                j = next[j];
            }
        }
        return next;
    }

}