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/*
* Copyright 2000-2022 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.converter;
import java.text.NumberFormat;
import java.text.ParsePosition;
import java.util.Locale;
import com.vaadin.data.Converter;
import com.vaadin.data.ErrorMessageProvider;
import com.vaadin.data.Result;
import com.vaadin.data.ValueContext;
/**
* A converter that converts from the number type T to {@link String} and back.
* Uses the given locale and {@link NumberFormat} for formatting and parsing.
* Automatically trims the input string, removing any leading and trailing white
* space.
* <p>
* Override and overwrite {@link #getFormat(Locale)} to use a different format.
* </p>
*
* @author Vaadin Ltd
* @since 8.0
*/
public abstract class AbstractStringToNumberConverter<T extends Number>
implements Converter<String, T> {
private final ErrorMessageProvider errorMessageProvider;
private T emptyValue;
/**
* Creates a new converter instance with the given empty string value and
* error message provider.
*
* @param emptyValue
* the presentation value to return when converting an empty
* string, may be <code>null</code>
* @param errorMessageProvider
* the error message provider to use if conversion fails
*
* @since 8.4
*/
protected AbstractStringToNumberConverter(T emptyValue,
ErrorMessageProvider errorMessageProvider) {
this.emptyValue = emptyValue;
this.errorMessageProvider = errorMessageProvider;
}
/**
* Creates a new converter instance with the given empty string value and
* error message.
*
* @param emptyValue
* the presentation value to return when converting an empty
* string, may be <code>null</code>
* @param errorMessage
* the error message to use if conversion fails
*/
protected AbstractStringToNumberConverter(T emptyValue,
String errorMessage) {
this(emptyValue, ctx -> errorMessage);
}
/**
* Returns the format used by
* {@link #convertToPresentation(Object, ValueContext)} and
* {@link #convertToModel(Object, ValueContext)}.
*
* @param locale
* The locale to use
* @return A NumberFormat instance
*/
protected NumberFormat getFormat(Locale locale) {
if (locale == null) {
locale = Locale.getDefault();
}
return NumberFormat.getNumberInstance(locale);
}
/**
* Convert the value to a Number using the given locale and
* {@link #getFormat(Locale)}.
*
* @param value
* The value to convert
* @param context
* The value context for conversion
* @return The converted value
*/
protected Result<Number> convertToNumber(String value,
ValueContext context) {
if (value == null) {
return Result.ok(null);
}
// Remove leading and trailing white space
value = value.trim();
// Parse and detect errors. If the full string was not used, it is
// an error.
ParsePosition parsePosition = new ParsePosition(0);
Number parsedValue = getFormat(context.getLocale().orElse(null))
.parse(value, parsePosition);
if (parsePosition.getIndex() != value.length()) {
return Result.error(getErrorMessage(context));
}
if (parsedValue == null) {
// Convert "" to the empty value
return Result.ok(emptyValue);
}
return Result.ok(parsedValue);
}
/**
* Gets the error message to use when conversion fails.
*
* @return the error message
*/
protected String getErrorMessage(ValueContext context) {
return errorMessageProvider.apply(context);
}
@Override
public String convertToPresentation(T value, ValueContext context) {
if (value == null) {
return null;
}
return getFormat(context.getLocale().orElse(null)).format(value);
}
}
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