com.vaadin.data.util.converter.StringToEnumConverter Maven / Gradle / Ivy
/*
* Copyright 2000-2014 Vaadin 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.vaadin.data.util.converter;
import java.util.EnumSet;
import java.util.Locale;
/**
* A converter that converts from {@link String} to an {@link Enum} and back.
*
* Designed to provide nice human readable strings for {@link Enum} classes
* where the constants are named SOME_UPPERCASE_WORDS. Will not necessarily work
* correctly for other cases.
*
*
* @author Vaadin Ltd
* @since 7.4
*/
public class StringToEnumConverter implements Converter {
@Override
public Enum convertToModel(String value, Class targetType,
Locale locale) throws ConversionException {
if (value == null || value.trim().equals("")) {
return null;
}
return stringToEnum(value, targetType, locale);
}
/**
* Converts the given string to the given enum type using the given locale
*
* Compatible with {@link #enumToString(Enum, Locale)}
*
* @param value
* The string value to convert
* @param enumType
* The type of enum to create
* @param locale
* The locale to use for conversion. If null, the JVM default
* locale will be used
* @return The enum which matches the given string
* @throws ConversionException
* if the conversion fails
*/
public static > T stringToEnum(String value,
Class enumType, Locale locale) throws ConversionException {
if (locale == null) {
locale = Locale.getDefault();
}
// Foo -> FOO
// Foo bar -> FOO_BAR
String result = value.replace(" ", "_").toUpperCase(locale);
try {
return Enum.valueOf(enumType, result);
} catch (Exception ee) {
// There was no match. Try to compare the available values to see if
// the constant is using something else than all upper case
try {
EnumSet set = EnumSet.allOf(enumType);
for (T e : set) {
if (e.name().toUpperCase(locale).equals(result)) {
return e;
}
}
} catch (Exception e) {
}
// Fallback did not work either, re-throw original exception so
// user knows what went wrong
throw new ConversionException(ee);
}
}
/**
* Converts the given enum to a human readable string using the given locale
*
* Compatible with {@link #stringToEnum(String, Class, Locale)}
*
* @param value
* The enum value to convert
* @param locale
* The locale to use for conversion. If null, the JVM default
* locale will be used
* @return A human readable string based on the enum
* @throws ConversionException
* if the conversion fails
*/
public static String enumToString(Enum value, Locale locale) {
if (locale == null) {
locale = Locale.getDefault();
}
String enumString = value.toString();
// FOO -> Foo
// FOO_BAR -> Foo bar
// _FOO -> _foo
String result = enumString.substring(0, 1).toUpperCase(locale);
result += enumString.substring(1).toLowerCase(locale).replace('_', ' ');
return result;
}
@Override
public String convertToPresentation(Enum value,
Class targetType, Locale locale)
throws ConversionException {
if (value == null) {
return null;
}
return enumToString(value, locale);
}
@Override
public Class getModelType() {
return Enum.class;
}
@Override
public Class getPresentationType() {
return String.class;
}
}