com.univocity.parsers.conversions.NullConversion Maven / Gradle / Ivy
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/*******************************************************************************
* Copyright 2016 uniVocity Software Pty Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
******************************************************************************/
package com.univocity.parsers.conversions;
/**
* Default implementation for conversions from input Objects of type I to output Objects of type O
*
* Extending classes must implement a proper String to T conversion in {@link ObjectConversion#fromString(String)}
*
This abstract class provides default results for conversions when the input is null.
*
* @author uniVocity Software Pty Ltd - [email protected]
*
* @param The object type resulting from conversions of values of type O.
* @param The object type resulting from conversions of values of type I.
*/
public abstract class NullConversion implements Conversion {
private O valueOnNullInput;
private I valueOnNullOutput;
/**
* Creates a Conversion from an object to another object of a different type, with default values to return when the input is null.
* The default constructor assumes the output of a conversion should be null when input is null
*/
public NullConversion() {
this(null, null);
}
/**
* Creates a Conversion from an object to another object of a different type, with default values to return when the input is null.
*
* @param valueOnNullInput default value of type O to be returned when the input object I is null. Used when {@link NullConversion#execute(Object)} is invoked.
* @param valueOnNullOutput default value of type I to be returned when an input of type I is null. Used when {@link NullConversion#revert(Object)} is invoked.
*/
public NullConversion(O valueOnNullInput, I valueOnNullOutput) {
this.valueOnNullInput = valueOnNullInput;
this.valueOnNullOutput = valueOnNullOutput;
}
/**
* Converts the given instance of type I to an instance of O
*
* @param input the input value of type I to be converted to an object of type O
*
* @return the conversion result, or the value of {@link NullConversion#valueOnNullInput} if the input object is null.
*/
@Override
public O execute(I input) {
if (input == null) {
return valueOnNullInput;
}
return fromInput(input);
}
/**
* Creates an instance of O from a I object
*
* @param input The object of type I to be converted to O
*
* @return an instance of O, converted from the I input.
*/
protected abstract O fromInput(I input);
/**
* Converts a value of type O back to a value of type I
*
* @param input the input of type O to be converted to an output I
*
* @return the conversion result, or the value of {@link NullConversion#valueOnNullOutput} if the input object is null.
*/
@Override
public I revert(O input) {
if (input == null) {
return valueOnNullOutput;
}
return undo(input);
}
/**
* Converts a value of type O back to I.
* @param input the input object to be converted to I
* @return the conversion result
*/
protected abstract I undo(O input);
/**
* returns a default value of type O to be returned when the input of type I is null. Used when {@link NullConversion#execute(Object)} is invoked.
*
* @return the default value of type O used when converting from a null I
*/
public O getValueOnNullInput() {
return valueOnNullInput;
}
/**
* returns default instance of I to be returned when an input of type O is null. Used when {@link NullConversion#revert(Object)} is invoked.
*
* @return the default I instance used when converting from a null O
*/
public I getValueOnNullOutput() {
return valueOnNullOutput;
}
/**
* defines the default value of type O which should be returned when {@link NullConversion#execute(Object)} is invoked with a null I..
*
* @param valueOnNullInput the default value of type T when converting from a null input
*/
public void setValueOnNullInput(O valueOnNullInput) {
this.valueOnNullInput = valueOnNullInput;
}
/**
* defines the default value of type I which should be returned when {@link NullConversion#revert(Object)} is invoked with a null O.
*
* @param valueOnNullOutput a default value of type I when converting from a null input
*/
public void setValueOnNullOutput(I valueOnNullOutput) {
this.valueOnNullOutput = valueOnNullOutput;
}
}