ArrayListHandler Class


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The org.apache.commons.dbutils.ArrayListHandler is the implementation of ResultSetHandler interface and is responsible to convert the ResultSet rows into a object[]. This class is thread safe.

Class Declaration

Following is the declaration for org.apache.commons.dbutils.ArrayListHandler class −

public class ArrayListHandler
   extends AbstractListHandler<Object[]>

Usage

  • Step 1 − Create a connection object.

  • Step 2 − Get implementation of ResultSetHandler as ArrayListHandler object.

  • Step 3 − Pass resultSetHandler to QueryRunner object, and make database operations.

Example

Following example will demonstrate how to read a list of records using ArrayListHandler class. We'll read available records in Employees Table as object[].

Syntax

List<Object> result = queryRunner.query(conn, "SELECT * FROM employees", new ArrayListHandler());       

Where,

  • resultHandler − ArrayListHandler object to map result sets to list of object[].

  • queryRunner − QueryRunner object to read employee object from database.

To understand the above-mentioned concepts related to DBUtils, let us write an example which will run a read query. To write our example, let us create a sample application.

Step Description
1 Update the file MainApp.java created under chapter DBUtils - First Application.
2 Compile and run the application as explained below.

Following is the content of the Employee.java.

public class Employee {
   private int id;
   private int age;
   private String first;
   private String last;
   public int getId() {
      return id;
   }
   public void setId(int id) {
      this.id = id;
   }
   public int getAge() {
      return age;
   }
   public void setAge(int age) {
      this.age = age;
   }
   public String getFirst() {
      return first;
   }
   public void setFirst(String first) {
      this.first = first;
   }
   public String getLast() {
      return last;
   }
   public void setLast(String last) {
      this.last = last;
   }
}

Following is the content of the MainApp.java file.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.dbutils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.ArrayListHandler;

public class MainApp {
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost:3306/emp";

   //  Database credentials
   static final String USER = "root";
   static final String PASS = "admin";

   public static void main(String[] args) throws SQLException {
      Connection conn = null;
      QueryRunner queryRunner = new QueryRunner();
      
      //Step 1: Register JDBC driver
      DbUtils.loadDriver(JDBC_DRIVER);

      //Step 2: Open a connection
      System.out.println("Connecting to database...");
      conn = DriverManager.getConnection(DB_URL, USER, PASS);        

      try {
         List<Object[]> result = queryRunner.query(conn, "SELECT * FROM employees"
            , new ArrayListHandler());  
         for(Object[] objects : result) {
            System.out.println(Arrays.toString(objects));
         }           
      } finally {
         DbUtils.close(conn);
      }        
   }
}

Once you are done creating the source files, let us run the application. If everything is fine with your application, it will print the following message.

[100, 18, Zara, Ali]
[101, 25, Mahnaz, Fatma]
[102, 30, Zaid, Khan]
[103, 28, Sumit, Mittal]
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