搞懂的问题（1）

import java.io.*;
import java.sql.*;
public class IPfind{     
public static void main(String[] args){
String ipstr = null;
  for(int j=11;j<131;j++){
       ipstr="192.168.24."+j;
  online(ipstr);
sql(ipstr);
 }
}


 private  static void online(String p){ 
String cont=null;
Process process = null;
String line =null;
      try
{
process = Runtime.getRuntime().exec(
 "Ping " + p + " -w 200 -n 1");   //注意：Ping 后面要加空格 例如：Ping 192.168.21.100
InputStream is = process.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader in = new BufferedReader(isr);
for(int m = 0;m <7; m++) {//设置循环，多次读行
line = in.readLine();   }
}catch (IOException e)
{
e.printStackTrace();
}
if(line.length() < 17 || line.substring(8,17).equals("timed out")){//判断条件：第9~17位是timed out
process.destroy();
    cont="   不在线";
System.out.println(p+"\t"+cont);
        }
  else{
    process.destroy();
        cont="   在线";
             System.out.println(p+"\t"+cont);
 }
      }
public static void sql(String gg){
   try {
String url1="jdbc:mysql://192.168.24.75:3306/test";
    Class.forName("com.mysql.jdbc.Driver").newInstance();
    Connection con=DriverManager.getConnection(url1,"root","123");
    Statement stmt=con.createStatement();
     int count1=stmt.executeUpdate("INSERT INTO cmd(con)  VALUES('"+gg+"')");
         stmt.close();
 con.close();
      System.out.println("成功导入数据库...");
 } catch (Exception ex) { 
ex.printStackTrace();
}    
   }
}