diff --git a/BasicInfoAPI/src/main/api/IServerInfo.java b/BasicInfoAPI/src/main/api/IServerInfo.java
index 3192663..264edc8 100644
--- a/BasicInfoAPI/src/main/api/IServerInfo.java
+++ b/BasicInfoAPI/src/main/api/IServerInfo.java
@@ -13,6 +13,7 @@ class ExtraDescr{
         public String text;
         public String color;
     }
+    boolean isAvailable();
     String getVersionName();
     int getVersionProtocol();
     int getMaxPlayer();
diff --git a/BasicInfoAPI/src/main/conn/MinecraftServer.java b/BasicInfoAPI/src/main/conn/MinecraftServer.java
index ecdde9e..6c9036a 100644
--- a/BasicInfoAPI/src/main/conn/MinecraftServer.java
+++ b/BasicInfoAPI/src/main/conn/MinecraftServer.java
@@ -24,6 +24,7 @@ public class MinecraftServer extends Thread implements IServerInfo {
     private String host;
     private int port=25565;
     private Response response=null;
+    private boolean available=false;
     public MinecraftServer(String host,int port)throws Exception {
         socket=new Socket(host,port);
         this.host=host;
@@ -38,6 +39,11 @@ public MinecraftServer(String host,int port)throws Exception {
         new PacketSend(0).write(dataOutputStream);
         try {
             response = new Gson().fromJson(new PacketRecv(dataInputStream).popString(), Response.class);
+            if (response==null){
+                available=false;
+                throw new EOFException("Invalid server response.");
+            }
+            available=true;
         }catch (EOFException e){//To change protocol.
             socket=new Socket(host,port);
             dataInputStream=new DataInputStream(socket.getInputStream());
@@ -67,6 +73,7 @@ public MinecraftServer(String host,int port)throws Exception {
                             (new String(bbase.pop(end),StandardCharsets.UTF_16BE));
                     response.players.max=Integer.parseInt
                             (new String(bbase.pop(end),StandardCharsets.UTF_16BE));
+                    available=true;
                 }
             }
         }
@@ -80,6 +87,11 @@ private class ByteBase{
         int index=0;
         ByteBase(byte[] byteArr){
             this.arr=byteArr;
+//            System.out.print("list:");
+//            for (byte b:byteArr){
+//                System.out.print(b+" ");
+//            }
+//            System.out.println();
         }
         public byte[] pop(byte[] end){
             ArrayList<Byte> byteArrayList=new ArrayList<>();
@@ -136,6 +148,10 @@ static class version{
         String favicon;
     }
 
+    @Override
+    public boolean isAvailable(){
+        return available;
+    }
 
     @Override
     public String getVersionName() {
diff --git a/BasicInfoAPI/src/test/conn/MinecraftServerTest.java b/BasicInfoAPI/src/test/conn/MinecraftServerTest.java
index b1a0a8f..455367d 100644
--- a/BasicInfoAPI/src/test/conn/MinecraftServerTest.java
+++ b/BasicInfoAPI/src/test/conn/MinecraftServerTest.java
@@ -6,6 +6,7 @@
 public class MinecraftServerTest {
     public static void main(String[] args)throws Exception {
         MinecraftServer minecraftServer=new MinecraftServer("localhost",25565);
+        System.out.println("available:"+minecraftServer.isAvailable());
         System.out.println("version:name:"+minecraftServer.getVersionName()+" protocol:"+minecraftServer.getVersionProtocol());
         System.out.println("defaultDescription:color:"+minecraftServer.getDefaultDescriptionColor()+" text:"+minecraftServer.getDefaultDescriptionText());
         IServerInfo.ExtraDescr[] extraDescrs=minecraftServer.getExtraDescription();
diff --git a/README.md b/README.md
index f891a96..1ed4599 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,23 @@ This repo contains several modules.Provides APIs for bot making or related proje
 
 ## BasicInfoAPI
 
-Supports to get basic info of a Minecraft server.Using the official client's way to get info that can be listed in Minecraft client's server list.
-Click the dir link to get further info.
+Supports to get basic info of a Minecraft server.  
+Using the official client's way to get info that can be listed in Minecraft client's server list.  
+Click the dir link to get further info.  
+Supported server version:
+1.17.x
+1.16.x
+1.15.x
+1.14.x
+1.13.x
+1.12.x
+1.11.x
+1.10.x
+1.9.x
+1.8.x
+1.7.x
+1.6.x
+1.4.x
+1.5.x
 
-Latest Release:0.1
\ No newline at end of file
+Latest Release:0.2
\ No newline at end of file