get JSF Expression Value - Java JSF

Java examples for JSF:UIComponent

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Description

get JSF Expression Value

Demo Code

/*/*from w  w  w.  j a  v a  2 s.c o  m*/
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */
import javax.el.ValueExpression;
import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
import javax.faces.el.EvaluationException;
import javax.faces.el.MethodBinding;
import javax.faces.el.ValueBinding;
import javax.faces.validator.Validator;
import javax.faces.validator.ValidatorException;
import java.util.Collection;

public class Main{
    @SuppressWarnings("unchecked")
    static <T> T getExpressionValue(UIComponent component,
            String attribute, T overrideValue, T defaultValue) {
        if (overrideValue != null) {
            return overrideValue;
        }
        ValueExpression ve = component.getValueExpression(attribute);
        if (ve != null) {
            return (T) ve.getValue(component.getFacesContext()
                    .getELContext());
        }
        return defaultValue;
    }
}

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