import java.lang.String;

public class Find {

	 
	public static void main(String[] args) {
		// TODO 自動生成方法存根
       FindString fs=new FindString("Hello,welcome to java! java","java");
       System.out.println(fs.s+" find start "+fs.subs+" is at position"+fs.findFirst());
       //System.out.println(fs.s+"find next "+fs.subs+" is at position"+fs.findNext(5));
       //找下一個子串
       int find=0;
       fs.findFirst();
       do{
    	   System.out.println("find position is"+find);
    	   find=fs.findNext(find+fs.subs.length());
       }while(find!=-1);
       
      FindReplaceString ns=new FindReplaceString("Hello,welcome to java! java","java","c++") ;
      System.out.println("new string is:"+ns.findFirstAndReplace());
       
	}
	

}
class FindString
{
	String s;
	String subs;
	FindString()
	{
		s="welcome to our school!";
		subs="lcom";
		
	}
	FindString(String s,String subs)
	{
		this.s =s;
		this.subs =subs;
	}
	
	int findFirst()
	{
		return s.indexOf(subs,0);
		
	}
	
	int findNext(int pos)
	{
		return s.indexOf(subs,pos);

	}
}

 
	class FindReplaceString  extends FindString
	{
        String news;
        
        FindReplaceString()
       {
           super();
       }
      
      FindReplaceString(String s, String subs,String news)
      {
        super(s, subs);
        this.news = news;
      }
       
      //這里請你完成findFirstAndReplace()
      //找subs在s中的第一個位置, 然后把
      //該subs用news代替, 然后返回一個
      //修改好的String
      String findFirstAndReplace()
      {
            StringBuffer sb = new StringBuffer(s);
          
            
            
            sb.replace(findFirst(),findFirst()+subs.length(), news);
           
            return sb.toString();                  
      }

      //從pos開始找下一個subs出現在s中的位置
      //用news代替它，然后返回修改好的String
     
      String findNextAndReplace(int pos)
      {
    	  StringBuffer sc=new StringBuffer(s);
          sc.replace(findNext(pos), findNext(pos)+subs.length(), news);
          return   sc.toString();  
           
}
}