求查找字符串中的字串，并把子串替换为指定的新子串的java算法。不能用java中的所以现成的替换方法。要自己写算法实现

Question

求查找字符串中的字串，并把子串替换为指定的新子串的java算法。不能用java中的所以现成的替换方法。要自己写算法实现

Answer 1

public class Other {
public static String replace(String content,String first,String second) {
int location = -1;
while((location = content.indexOf(first)) >= 0){
content = content.substring(0,location) + second + content.substring(location + first.length());
}
return content;
} public static void main(String args[]) {
// 自己写的方法
String str = "abcdefgabasdfgs";
System.out.println(replace(str,"fg","123"));

// 正则
System.out.println(str.replaceAll("fg", "123"));
}
}

Answer 2

首先要匹配 之后就好办了.
关于匹配方面的知识,可以用KMP算法或hash表
具体记不清了 在网上搜了一个
匹配的例子:
public String getMaxMatch(String a,String b) {   
        StringBuffer tmp = new StringBuffer();   
        String maxString = "";   
        int max = 0;   
        int len = 0;   
        char[] aArray = a.toCharArray();   
        char[] bArray = b.toCharArray();   
        int posA = 0;   
        int posB = 0;   
        while(posA<aArray.length-max) {   
            posB = 0;   
            while(posB<(bArray.length-max)) {                                   
                 if(aArray[posA]==bArray[posB]) {   
                      len = 1;   
                      tmp = new StringBuffer();   
                      tmp.append(aArray[posA]);                                           
                      while((posA+len<aArray.length)&&(posB+len<bArray.length)&&(aArray[posA+len]==bArray[posB+len])) {   
                           tmp.append(aArray[posA+len]);   
                           len++;   
                      }   
                      if(len>max) {   
                            max = len;   
                            maxString = tmp.toString();   
                      }   
                 }   
                      posB++;   
            }   
                      posA++;   
         }           
            return maxString;                       
    }