How Can we create a topic in Kafka from the IDE using API

In Kafka 0.8.1+ — the latest version of Kafka as of today — you can programmatically create a new topic via AdminCommand. The functionality of CreateTopicCommand (part of the older Kafka 0.8.0) that was mentioned in one of the previous answers to this question was moved to AdminCommand.

Scala example for Kafka 0.8.1:

import kafka.admin.AdminUtils
import kafka.utils.ZKStringSerializer
import org.I0Itec.zkclient.ZkClient

// Create a ZooKeeper client
val sessionTimeoutMs = 10000
val connectionTimeoutMs = 10000
// Note: You must initialize the ZkClient with ZKStringSerializer.  If you don't, then
// createTopic() will only seem to work (it will return without error).  The topic will exist in
// only ZooKeeper and will be returned when listing topics, but Kafka itself does not create the
// topic.
val zkClient = new ZkClient("zookeeper1:2181", sessionTimeoutMs, connectionTimeoutMs,
    ZKStringSerializer)

// Create a topic named "myTopic" with 8 partitions and a replication factor of 3
val topicName = "myTopic"
val numPartitions = 8
val replicationFactor = 3
val topicConfig = new Properties
AdminUtils.createTopic(zkClient, topicName, numPartitions, replicationFactor, topicConfig)

Build dependencies, using sbt as example:

libraryDependencies ++= Seq(
  "com.101tec" % "zkclient" % "0.4",
  "org.apache.kafka" % "kafka_2.10" % "0.8.1.1"
    exclude("javax.jms", "jms")
    exclude("com.sun.jdmk", "jmxtools")
    exclude("com.sun.jmx", "jmxri"),
  ...
)

EDIT: Added Java example for Kafka 0.9.0.0 (latest version as of Jan 2016).

Maven dependencies:

<dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka_2.11</artifactId>
    <version>0.9.0.0</version>
</dependency>
<dependency>
    <groupId>com.101tec</groupId>
    <artifactId>zkclient</artifactId>
    <version>0.7</version>
</dependency>

Code:

import org.I0Itec.zkclient.ZkClient;
import org.I0Itec.zkclient.ZkConnection;

import java.util.Properties;

import kafka.admin.AdminUtils;
import kafka.utils.ZKStringSerializer$;
import kafka.utils.ZkUtils;

public class KafkaJavaExample {

  public static void main(String[] args) {
    String zookeeperConnect = "zkserver1:2181,zkserver2:2181";
    int sessionTimeoutMs = 10 * 1000;
    int connectionTimeoutMs = 8 * 1000;
    // Note: You must initialize the ZkClient with ZKStringSerializer.  If you don't, then
    // createTopic() will only seem to work (it will return without error).  The topic will exist in
    // only ZooKeeper and will be returned when listing topics, but Kafka itself does not create the
    // topic.
    ZkClient zkClient = new ZkClient(
        zookeeperConnect,
        sessionTimeoutMs,
        connectionTimeoutMs,
        ZKStringSerializer$.MODULE$);

    // Security for Kafka was added in Kafka 0.9.0.0
    boolean isSecureKafkaCluster = false;
    ZkUtils zkUtils = new ZkUtils(zkClient, new ZkConnection(zookeeperConnect), isSecureKafkaCluster);

    String topic = "my-topic";
    int partitions = 2;
    int replication = 3;
    Properties topicConfig = new Properties(); // add per-topic configurations settings here
    AdminUtils.createTopic(zkUtils, topic, partitions, replication, topicConfig);
    zkClient.close();
  }

}

EDIT 2: Added Java example for Kafka 0.10.2.0 (latest version as of April 2017).

Maven dependencies:

<dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka_2.11</artifactId>
    <version>0.10.2.0</version>
</dependency>
<dependency>
    <groupId>com.101tec</groupId>
    <artifactId>zkclient</artifactId>
    <version>0.9</version>
</dependency>

Code:

import org.I0Itec.zkclient.ZkClient;
import org.I0Itec.zkclient.ZkConnection;

import java.util.Properties;

import kafka.admin.AdminUtils;
import kafka.admin.RackAwareMode;
import kafka.utils.ZKStringSerializer$;
import kafka.utils.ZkUtils;

public class KafkaJavaExample {

  public static void main(String[] args) {
    String zookeeperConnect = "zkserver1:2181,zkserver2:2181";
    int sessionTimeoutMs = 10 * 1000;
    int connectionTimeoutMs = 8 * 1000;

    String topic = "my-topic";
    int partitions = 2;
    int replication = 3;
    Properties topicConfig = new Properties(); // add per-topic configurations settings here

    // Note: You must initialize the ZkClient with ZKStringSerializer.  If you don't, then
    // createTopic() will only seem to work (it will return without error).  The topic will exist in
    // only ZooKeeper and will be returned when listing topics, but Kafka itself does not create the
    // topic.
    ZkClient zkClient = new ZkClient(
        zookeeperConnect,
        sessionTimeoutMs,
        connectionTimeoutMs,
        ZKStringSerializer$.MODULE$);

    // Security for Kafka was added in Kafka 0.9.0.0
    boolean isSecureKafkaCluster = false;

    ZkUtils zkUtils = new ZkUtils(zkClient, new ZkConnection(zookeeperConnect), isSecureKafkaCluster);
    AdminUtils.createTopic(zkUtils, topic, partitions, replication, topicConfig, RackAwareMode.Enforced$.MODULE$);
    zkClient.close();
  }

}