tJava - 6.3

Talend Open Studio for Big Data Components Reference Guide

EnrichVersion
6.3
EnrichProdName
Talend Open Studio for Big Data
task
Data Governance
Data Quality and Preparation
Design and Development
EnrichPlatform
Talend Studio

Function

tJava enables you to enter personalized code in order to integrate it in Talend program. You can execute this code only once.

Purpose

tJava makes it possible to extend the functionalities of a Talend Job using custom Java commands.

tJava properties

Component family

Custom Code

 

Basic settings

Code

Type in the Java code you want to execute according to the task you need to perform. For further information about Java functions syntax specific to Talend, see Talend Studio Help Contents (Help > Developer Guide > API Reference).

For a complete Java reference, check http://docs.oracle.com/javaee/6/api/

Advanced settings

Import

Enter the Java code to import, if necessary, external libraries used in the Code field of the Basic settings view.

 

tStatCatcher Statistics

Select this check box to gather the Job processing metadata at a Job level as well as at each component level.

Global Variables

ERROR_MESSAGE: the error message generated by the component when an error occurs. This is an After variable and it returns a string. This variable functions only if the Die on error check box is cleared, if the component has this check box.

A Flow variable functions during the execution of a component while an After variable functions after the execution of the component.

To fill up a field or expression with a variable, press Ctrl + Space to access the variable list and choose the variable to use from it.

For further information about variables, see Talend Studio User Guide.

Usage

This component is generally used as a one-component subjob.

Limitation

You should know Java language.

Scenario: Printing out a variable content

The following scenario is a simple demo of the extended application of the tJava component. The Job aims at printing out the number of lines being processed using a Java command and the global variable provided in Talend Studio.

Setting up the Job

  1. Select and drop the following components from the Palette onto the design workspace: tFileInputDelimited, tFileOutputExcel, tJava.

  2. Connect the tFileInputDelimited to the tFileOutputExcel using a Row Main connection. The content from a delimited txt file will be passed on through the connection to an xls-type of file without further transformation.

  3. Then connect the tFileInputDelimited component to the tJava component using a Trigger > On Subjob Ok link. This link sets a sequence ordering tJava to be executed at the end of the main process.

Configuring the input component

  1. Set the Basic settings of the tFileInputDelimited component.

  2. Define the path to the input file in the File name field.

    The input file used in this example is a simple text file made of two columns: Names and their respective Emails.

  3. Click the Edit Schema button, and set the two-column schema. Then click OK to close the dialog box.

  4. When prompted, click OK to accept the propagation, so that the tFileOutputExcel component gets automatically set with the input schema.

Configuring the output component

Set the output file to receive the input content without changes. If the file does not exist already, it will get created.

In this example, the Sheet name is Email and the Include Header box is selected.

Configuring the tJava component

  1. Then select the tJava component to set the Java command to execute.

  2. In the Code area, type in the following command:

    String var = "Nb of line processed: ";
    var = var + globalMap.get("tFileInputDelimited_1_NB_LINE");
    System.out.println(var);

    In this use case, we use the NB_Line variable. To access the global variable list, press Ctrl + Space bar on your keyboard and select the relevant global parameter.

Job execution

Save your Job and press F6 to execute it.

The content gets passed on to the Excel file defined and the Number of lines processed are displayed on the Run console.