2.4.1 Your First Java Application

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You've got GridDB installed using the Quickstart blogpost and now it's time to start developing your first Java application. This blog post will take you through the basics:

First, the required import statements:

import com.toshiba.mwcloud.gs.Collection;
import com.toshiba.mwcloud.gs.GSException;
import com.toshiba.mwcloud.gs.GridStore;
import com.toshiba.mwcloud.gs.GridStoreFactory;
import com.toshiba.mwcloud.gs.Query;
import com.toshiba.mwcloud.gs.RowKey;
import com.toshiba.mwcloud.gs.RowSet;

The container schema is defined as a static Class in Java.

static class Person {
	@RowKey String name;
	int age;
}
static class HeartRate {
	@RowKey Date ts;
	int heartRate;
        String activity;
}

To connect to GridDB, you create a Properties instance with the particulars of your GridDB installation.

Properties props = new Properties();
props.setProperty("notificationAddress", "239.0.0.1");
props.setProperty("notificationPort", "31999");
props.setProperty("clusterName", "defaultCluster");
props.setProperty("user", "admin");
props.setProperty("password", "admin");
GridStore store = GridStoreFactory.getInstance().getGridStore(props);

To perform queries or write records, you first need to get the container:

Collection<String, Person> people = store.putCollection("PEOPLE", Person.class);

Querying is similar to SQL/JDBC drivers.

Query<Person< query = col.query("select * where name = 'John'");
RowSet<Person> rs = query.fetch(false);
while (rs.hasNext()) {
	// Update the searched Row
	Person person1 = rs.next();
        System.out.println("Name: "+ person1.name +" Age: "+ person1.age)
}

Writing is simple...

HeartRate hr = new HeartRate();
hr.ts = new Date();
hr.heartrate = 60;
hr.activity = "resting";
TimeSeries<HeartRate> heartRate = store.putTimeSeries("HR_"+person1.name, HeartRate.class);
heartRate.put(hr);

Updating is simple:

Query<Person> query = col.query("select * where name = 'John'");
RowSet<Person> rs = query.fetch(true);
while (rs.hasNext()) {
	// Update the searched Row
	Person person1 = rs.next();
        person1.age++;
        rs.update(person1);
}

To compile use the following snippet:

$ cd gsSample/
$ export CLASSPATH=$CLASSPATH:/usr/share/java/gridstore.jar
$ javac Sample1.java
$ cd .. && java gsSample/Sample1

Alternatively, you can check out how to use maven with GridDB here.