univocity-parsers 2.9.1 · com.univocity.parsers.annotations.HeaderTransformer

A transformer of headers used in Nested attributes. Used to reassign header names/indexes of attributes of a Nested class which is useful when multiple Nested attributes of the same type are used within a class. For example, consider the Wheel class defined as:


public class Wheel {
    @Parsed
    String brand;

    @Parsed
    int miles;
}

And a Car which has four Wheels:


public static class Car {
		@Nested
		Wheel frontLeft;

		@Nested
		Wheel frontRight;

		@Nested
		Wheel rearLeft;

		@Nested
		Wheel rearRight;
}

The HeaderTransformer allows us to "rename" the attributes of each different Wheel of the Car so that input columns can be assigned to the appropriate places. Assuming an input with headers

frontLeftWheelBrand,frontLeftWheelMiles,frontRightWheelBrand,frontRightWheelMiles,rearLeftWheelBrand,rearLeftWheelMiles,rearRightWheelBrand,rearRightWheelMiles

, a HeaderTransformer can be created like this to assign a prefix in front of the header names derived from Wheel (originally just "brand" and "miles"):


public static class PrefixTransformer extends HeaderTransformer {

		private String prefix;

		public PrefixTransformer(String... args) {
			prefix = args[0];
       }

		@Override
		public String transformName(Field field, String name) {
			return prefix + Character.toUpperCase(name.charAt(0)) + name.substring(1);
       }
}

This allows us to to define the Car class as:


public static class Car {
		@Nested(headerTransformer = PrefixTransformer.class, args = "frontLeftWheel")
		Wheel frontLeft;

		@Nested(headerTransformer = PrefixTransformer.class, args = "frontRightWheel")
		Wheel frontRight;

		@Nested(headerTransformer = PrefixTransformer.class, args = "rearLeftWheel")
		Wheel rearLeft;

		@Nested(headerTransformer = PrefixTransformer.class, args = "rearRightWheel")
		Wheel rearRight;
}

The above annotation will prefix the frontLeft fields ("brand" and "miles") with "frontLeftWheel", effectively forming the header "frontLeftWheelBrand" and "frontLeftWheelMiles", which will match the input headers and assign the correct values to the correct Wheel instance

Important Note

It is mandatory to define a constructor that takes String[] as a parameter. The actual parameter values come from Nested#args() to allow custom configuration of the concrete HeaderTransformer instance.

Access	Constructor and Description
public	HeaderTransformer()

Method Summary

Modifier and Type	Method and Description
public final int	transformIndex(AnnotatedElement element, int index)
public int	Returns: the transformed position to be used to read/write values from/to the given field. transformIndex(Field the field of a `Nested` class whose header will be transformed field, int the current column position associated with the field of the `Nested` class index) Transforms a header index
public int	Returns: the transformed position to be used to read/write values from/to the given method. transformIndex(Method the method of a `Nested` class whose header will be transformed method, int the current column position associated with the method of the `Nested` class index) Transforms a header index
public final String	transformName(AnnotatedElement element, String name)
public String	Returns: the transformed header name to be used to read/write values from/to the given field. transformName(Field the field of a `Nested` class whose header will be transformed field, String the current header name associated with the field of the `Nested` class name) Transforms a header name
public String	Returns: the transformed header name to be used to read/write values from/to the given method. transformName(Method the method of a `Nested` class whose header will be transformed method, String the current header name associated with the method of the `Nested` class name) Transforms a header name

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

HeaderTransformer	back to summary
public HeaderTransformer()

Method Detail

transformIndex	back to summary
public final int transformIndex(AnnotatedElement element, int index)

transformIndex back to summary

transformIndex	back to summary
public int transformIndex(Field field, int index) Transforms a header index Parameters field:Field the field of a `Nested` class whose header will be transformed index:int the current column position associated with the field of the `Nested` class Returns:int the transformed position to be used to read/write values from/to the given field.

public int transformIndex(Field field, int index)

Transforms a header index

Parameters

field:Field: the field of a Nested class whose header will be transformed
index:int: the current column position associated with the field of the Nested class

Returns:int

the transformed position to be used to read/write values from/to the given field.

transformIndex back to summary

transformIndex	back to summary
public int transformIndex(Method method, int index) Transforms a header index Parameters method:Method the method of a `Nested` class whose header will be transformed index:int the current column position associated with the method of the `Nested` class Returns:int the transformed position to be used to read/write values from/to the given method.

public int transformIndex(Method method, int index)

Transforms a header index

Parameters

method:Method: the method of a Nested class whose header will be transformed
index:int: the current column position associated with the method of the Nested class

Returns:int

the transformed position to be used to read/write values from/to the given method.

transformName	back to summary
public final String transformName(AnnotatedElement element, String name)

transformName back to summary

transformName	back to summary
public String transformName(Field field, String name) Transforms a header name Parameters field:Field the field of a `Nested` class whose header will be transformed name:String the current header name associated with the field of the `Nested` class Returns:String the transformed header name to be used to read/write values from/to the given field.

public String transformName(Field field, String name)

Transforms a header name

Parameters

field:Field: the field of a Nested class whose header will be transformed
name:String: the current header name associated with the field of the Nested class

Returns:String

the transformed header name to be used to read/write values from/to the given field.

transformName back to summary

transformName	back to summary
public String transformName(Method method, String name) Transforms a header name Parameters method:Method the method of a `Nested` class whose header will be transformed name:String the current header name associated with the method of the `Nested` class Returns:String the transformed header name to be used to read/write values from/to the given method.

public String transformName(Method method, String name)

Transforms a header name

Parameters

method:Method: the method of a Nested class whose header will be transformed
name:String: the current header name associated with the method of the Nested class

Returns:String

the transformed header name to be used to read/write values from/to the given method.

public abstract Class HeaderTransformer

Constructor Summary

Method Summary

Constructor Detail

Method Detail