Check jedis is connected before executing commands

src/main/java/redis/clients/jedis/Client.java

@@ -21,7 +21,11 @@ public class Client {
 	this.host = host;
     }
 
-    protected Client sendCommand(String name, String... args) {
+    protected Client sendCommand(String name, String... args)
+	    throws JedisException {
+	if (!isConnected()) {
+	    throw new JedisException("Please connect Jedis before using it.");
+	}
 	protocol.sendCommand(outputStream, name, args);
 	return this;
     }

src/main/java/redis/clients/jedis/Jedis.java

@@ -23,7 +23,7 @@ public class Jedis extends Client {
 	return sendCommand("GET", key).getBulkReply();
     }
 
-    public void quit() {
+    public void quit() throws JedisException {
 	sendCommand("QUIT");
     }