Over a million developers have joined DZone.
{{announcement.body}}
{{announcement.title}}

Java Holiday Calendar 2016 (Day 7): Access Databases With Streams

DZone's Guide to

Java Holiday Calendar 2016 (Day 7): Access Databases With Streams

Want to query your database with Java? See how Speedment and Java 8's streams can help you get to your data.

· Java Zone
Free Resource

The single app analytics solutions to take your web and mobile apps to the next level.  Try today!  Brought to you in partnership with CA Technologies

Image title

Today's tip is about querying databases using Java 8 streams. By adding both a runtime and plugin dependency to open-source Speedment in your application's Maven POM file, you get access to standard stream implementations of all the database's tables. For MySQL, your POM file could look like this:

<properties>
    <speedment.version="">3.0.1</speedment.version>
    <db.groupid>mysql</db.groupid>
    <db.artifactid>mysql-connector-java</db.artifactid>
    <db.version>5.1.39</db.version>
</properties>

<build>
    <plugins>
        <plugin>
            <groupid>com.speedment</groupid>
            <artifactid>speedment-maven-plugin</artifactid>
            <version>${speedment.version}</version>
            <dependencies>
                <dependency>
                    <groupid>${db.groupId}</groupid>
                    <artifactid>${db.artifactId}</artifactid>
                    <version>${db.version}</version>
                </dependency>
            </dependencies> 
        </plugin>
    </plugins>
</build>

<dependencies>
    <dependency>
        <groupid>com.speedment</groupid>
        <artifactid>runtime</artifactid>
        <version>${speedment.version}</version>
        <type>pom</type>
    </dependency>
    <dependency>
        <groupid>${db.groupId}</groupid>
        <artifactid>${db.artifactId}</artifactid>
        <version>${db.version}</version>
    </dependency>
</dependencies>


Read more on how to configure your POM file for other database types here, which is also the place to be if you want to learn more on Speedment and how to write Speedment applications.

Do This

users.stream()
    .filter(EMAIL.endsWith(".com"))
    .forEach(System.out::println);


Don't Do This

Connection conn = null;
Statement stmt = null;
try {
      //STEP 2: Register JDBC driver
      Class.forName("com.mysql.jdbc.Driver");

      //STEP 3: Open a connection
      conn = DriverManager.getConnection(DB_URL, USER, PASS);

      //STEP 4: Execute a query
      stmt = conn.createStatement();

      String sql = "SELECT id, first, last, age, email FROM user";
      ResultSet rs = stmt.executeQuery(sql);

      //STEP 5: Extract data from result set
      while(rs.next()){
         //Retrieve columns
         int id  = rs.getInt("id");
         int age = rs.getInt("age");
         String first = rs.getString("first");
         String last = rs.getString("last");
         String email = rs.getString("email");

         if (email.endsWith(".com")) {
             //Display values
             System.out.print("ID: " + id);
             System.out.print(", Age: " + age);
             System.out.print(", First: " + first);
             System.out.print(", Last: " + last);
             System.out.println(", E-mail: " + email);
         }
      }
      rs.close();
   } catch(SQLException se){
      //Handle errors for JDBC
      se.printStackTrace();
   } catch(Exception e){
      //Handle errors for Class.forName
      e.printStackTrace();
   } finally {
      //finally block used to close resources
      try{
         if(stmt!=null)
            conn.close();
      } catch(SQLException se){
      }// do nothing
      try{
         if(conn!=null)

            conn.close();

        }catch(SQLException se){

        se.printStackTrace();
    }
}


CA App Experience Analytics, a whole new level of visibility. Learn more. Brought to you in partnership with CA Technologies.

Topics:
java ,streams ,database query

Opinions expressed by DZone contributors are their own.

THE DZONE NEWSLETTER

Dev Resources & Solutions Straight to Your Inbox

Thanks for subscribing!

Awesome! Check your inbox to verify your email so you can start receiving the latest in tech news and resources.

X

{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}