新手求助(字符串问题)

import java.io.*;
public class ArraysSubstring {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str="";
        String[] newstr=null;
        System.out.println("请输入字符串");
        try{
            BufferedReader in=
                new BufferedReader(new InputStreamReader(System.in));
            str=in.readLine();
        }catch(IOException e){};
        System.out.println("原字符串为:"+str);
        System.out.print("分割后的字符串为:");
        newstr=new String[str.length()/3];
        for(int i=1;i*3<=str.length();i++){
            newstr[i-1]=str.substring(3*(i-1),i*3);
        }
        for(int i = 0;i<newstr.length;i++)
            System.out.println(newstr[i]);
    }
}