User Defined Java Expression

Description

This transform allows you to enter User Defined Java Expressions as a basis for the calculation of new values.

If you have a Java expression like :

  1. C=A+B

Then you can simply enter the right side of the expression in the dialog:

  1. A+B

The values are exposed to the expressions as the Java objects they are :

Data typeJava Class

BigNumber

BigDecimal

Binary

byte[]

Date

java.util.Date

Integer

java.lang.Long

Number

java.lang.Double

String

java.lang.String

Options

OptionDescription

New Field

The new field in the data stream. If you want to overwrite an existing field, you need to define the field here and in the “Replace value” option.

Java Expression

The Java Expression, see examples below.

Value Type

Type

Length

Length

Precision

Precision

Replace value

Select this identical to the “New field” name when you want to replace

Metadata Injection Support

All fields of this transform support metadata injection. You can use this transform with ETL Metadata Injection to pass metadata to your pipeline at runtime.

Examples

Add 2 integers, A and B

  1. A+B

Concatenate 2 Strings : firstname and name and put a space in between

  1. firstname+" "+name

or if you really care about performance, this might be faster:

  1. new StringBuffer(firstname).append(" ").append(name).toString()

Use native Java and API functions

  1. System.getProperty("os.name")

Business rules (If / Then / Else)

  1. a<c?true:false

This can be more complicated

  1. a<c?(a==1?1:2):3

even with OR and AND and other operators and functions

Using Constants

If you use a constant, you may need to define the right type in some expressions otherwise it could throw:

Incompatible expression types “int” and “java.lang.Long”

To solve this, use:

  1. test == null ? new Long(0) : test

In this case, it checks if test is null and replaces with zero. If it is not null, it will return test.

Cut a string from end and test for null and minimal length

Imagine you have input strings with

  1. Orlando FL
  2. New York NY

and you want to separate the state and city, you could use the following expressions:

For state (get the last 2 characters):

  1. location != null && location.length()>2 ? location.substring(location.length()-2, location.length()) : null

For city (get the beginning without the last 2 characters and trim):

  1. location != null && location.length()>2 ? location.substring(0, location.length()-2).trim() : location

Functionality of a LIKE operator (contains string) and replacing values

The following example returns 1 when abc is within the source string, otherwise 2. It returns also 2 when the source string is null. The return values could be of value type Integer.

  1. samplestr !=null && samplestr.indexOf("abc")>-1 ? 1 : 2