private static boolean isReachable(String ip) {
        try {
            boolean reachable = false;
    
            Process p = Runtime.getRuntime().exec("ping -n 1 " + ip);
            BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
            String line = null;
            StringBuilder sb = new StringBuilder();
            while ((line = br.readLine()) != null) {
                if (line.length() != 0)
                    sb.append(line + "\r\n");
            }
    
            // When there is TTL When it appears , It means connected 
            reachable = sb.toString().contains("TTL");
            br.close();
            return reachable;
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return false;
        }
    }

public static void main(String[] args) throws IOException {
    	InetAddress host = InetAddress.getLocalHost();    // Create a native object 
    	String ip = host.getHostAddress();                // Get native ip address 
    	System.out.println(" Local machine ip the address is ：" + ip);
    	String pre_ip = ip.substring(0,ip.lastIndexOf('.')+1);
    	ThreadPoolExecutor tpe = new ThreadPoolExecutor(100, 200 , 5, TimeUnit.SECONDS,
    			new LinkedBlockingDeque<Runnable>());     // Thread pool processing 
    	
    	for (int i = 1; i <= 255; i++)
    	{
    		final int j = i;
    		tpe.execute(new Runnable()
			{
				@Override
				public void run()
				{
					Process P;
					try
					{
						P = Runtime.getRuntime().exec("ping " + pre_ip + j);
						BufferedReader br = new BufferedReader(new InputStreamReader(P.getInputStream(), "GBK"));
			    		String temp = null;
			    		boolean tag = false;
			    		while ((temp = br.readLine())!=null)
						{
							if (temp.contains("TTL"))
							{
								tag = true;
								break;
							}
						}
			    		if (tag)
			    			System.out.println(" Available ip address ：" + pre_ip + j);
					} catch (IOException e)
					{
						System.out.println("wocao?");
						e.printStackTrace();
					}
				}
			});
    		
    	}
    }

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;

public class JAVAOfIP {
	//  Test ping
	public static void pingIP() throws IOException {
		List<String> IPs=new ArrayList<>();
		List<String> DIPs=new ArrayList<>();
		String localIP = getIP();
		//  Get the content before the last decimal point 
		String ip = localIP.substring(0, localIP.lastIndexOf('.') + 1);
		for(int i=0;i<256;i++) {
			Process p = Runtime.getRuntime().exec("ping "+ip+i);
			System.out.println(" Testing "+ip+i);
			BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
			String line = null;
			StringBuilder sb = new StringBuilder();
			while ((line = br.readLine()) != null) {
				if (line.length() != 0) {
					sb.append(line + "\r\n");
				}
			}
			if((sb.indexOf("ms"))!=-1) {
				IPs.add(ip+i);
				System.out.println(ip+i+" Can connect ");
			}else {
				DIPs.add(ip+i);
				System.out.println(ip+i+" Can't connect ");
			}
		}
	}

	//  Get native ip
	public static String getIP() throws UnknownHostException {
		InetAddress host = InetAddress.getLocalHost();
		String ip = host.getHostAddress();
		System.out.println(" Local machine ip address ：" + ip);
		return ip;
	}

	public static void main(String[] args) throws IOException {
		pingIP();
	}
}

package how2jwangluo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class TestSocket2
{
    public static void main(String[] args) throws IOException {

        Process p = Runtime.getRuntime().exec("ping "+"192.168.2.106");
        BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
        String line = null;
        StringBuilder sb = new StringBuilder();
        while ((line=br.readLine())!=null)
        {
            if (line.length()!=0)
                sb.append(line+"\r\n");
        }
        System.out.println(" The message returned by this command is : ");
        System.out.println(sb.toString());
    }
}

import java.io.*;
import java.util.*;
import java.net.*;
public class Checkip {
 
    public static void main(String[] args) throws IOException {
        InetAddress host = InetAddress.getLocalHost();
        String hosth=host.getHostAddress();// obtain ip address 
        String ip=hosth.substring(0,hosth.lastIndexOf('.')+1);// Get the content before the last decimal point 
        int y=0;// The initial value of the last digit 
        List <String>iplist=new ArrayList<String>();// It can be used IP List 
        List <String>badip=new ArrayList<String>();// Unusable IP List 
        
        StringBuilder sb = new StringBuilder();
        Boolean check = true;
        while(check){
            y++;// Every cycle adds a bit 
            String faip="";
            faip=ip+y;// Put... Before the last decimal point ip Address and y combination 
            Process p = Runtime.getRuntime().exec("ping " +faip);// function ping
            
            // Read this process p Text in 
            BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
            String line = null;
            int cc=0;// Number of initialization cycles 
            while(cc<2&&(line=br.readLine())!=null){
                cc++;
                if (line.length() != 0){
                    sb.append(line + "\r\n");// Store the obtained text in sb Inside 
                } 
            }
                     
            while ((line = br.readLine()) != null) {
                System.out.println("ping "+faip);// Let's see how many ip Yes 
                if(line.contains("timeout")){
                    String bip="ip:" +faip+" Not available ";// contain timeout Proof not available 
                    badip.add(bip);// Will ip join badip of list
                }
                if (y==255){
                    System.out.println(" The message returned by this command is ：");
                    System.out.println(sb.toString());// While ending the whole cycle print this sb Stored information 
                    check=false;
                    break;
                } 
                if(line.contains("ttl")){// If... Is included ttl(time to live) Just 
                    String newip=faip+" Is available ip";// Will be available ip join iplist  of list  Inside 
                    iplist.add(newip);
                    break;
                }break;
            }  br.close();     
        }System.out.println(iplist);// Output available ip
        System.out.println(badip);// Output not available ip

    } 
}