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ActiveMQ example source code file (ArithmeticExpression.java)

This example ActiveMQ source code file (ArithmeticExpression.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

arithmeticexpression, cannot, double, expression, expression, integer, long, number, number, object, object, runtimeexception, string, string

The ActiveMQ ArithmeticExpression.java source code

/**
 * 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.
 */
package org.apache.activemq.filter;

import javax.jms.JMSException;

/**
 * An expression which performs an operation on two expression values
 * 
 * 
 */
public abstract class ArithmeticExpression extends BinaryExpression {

    protected static final int INTEGER = 1;
    protected static final int LONG = 2;
    protected static final int DOUBLE = 3;

    /**
     * @param left
     * @param right
     */
    public ArithmeticExpression(Expression left, Expression right) {
        super(left, right);
    }

    public static Expression createPlus(Expression left, Expression right) {
        return new ArithmeticExpression(left, right) {
            protected Object evaluate(Object lvalue, Object rvalue) {
                if (lvalue instanceof String) {
                    String text = (String)lvalue;
                    String answer = text + rvalue;
                    return answer;
                } else if (lvalue instanceof Number) {
                    return plus((Number)lvalue, asNumber(rvalue));
                }
                throw new RuntimeException("Cannot call plus operation on: " + lvalue + " and: " + rvalue);
            }

            public String getExpressionSymbol() {
                return "+";
            }
        };
    }

    public static Expression createMinus(Expression left, Expression right) {
        return new ArithmeticExpression(left, right) {
            protected Object evaluate(Object lvalue, Object rvalue) {
                if (lvalue instanceof Number) {
                    return minus((Number)lvalue, asNumber(rvalue));
                }
                throw new RuntimeException("Cannot call minus operation on: " + lvalue + " and: " + rvalue);
            }

            public String getExpressionSymbol() {
                return "-";
            }
        };
    }

    public static Expression createMultiply(Expression left, Expression right) {
        return new ArithmeticExpression(left, right) {

            protected Object evaluate(Object lvalue, Object rvalue) {
                if (lvalue instanceof Number) {
                    return multiply((Number)lvalue, asNumber(rvalue));
                }
                throw new RuntimeException("Cannot call multiply operation on: " + lvalue + " and: " + rvalue);
            }

            public String getExpressionSymbol() {
                return "*";
            }
        };
    }

    public static Expression createDivide(Expression left, Expression right) {
        return new ArithmeticExpression(left, right) {

            protected Object evaluate(Object lvalue, Object rvalue) {
                if (lvalue instanceof Number) {
                    return divide((Number)lvalue, asNumber(rvalue));
                }
                throw new RuntimeException("Cannot call divide operation on: " + lvalue + " and: " + rvalue);
            }

            public String getExpressionSymbol() {
                return "/";
            }
        };
    }

    public static Expression createMod(Expression left, Expression right) {
        return new ArithmeticExpression(left, right) {

            protected Object evaluate(Object lvalue, Object rvalue) {
                if (lvalue instanceof Number) {
                    return mod((Number)lvalue, asNumber(rvalue));
                }
                throw new RuntimeException("Cannot call mod operation on: " + lvalue + " and: " + rvalue);
            }

            public String getExpressionSymbol() {
                return "%";
            }
        };
    }

    protected Number plus(Number left, Number right) {
        switch (numberType(left, right)) {
        case INTEGER:
            return new Integer(left.intValue() + right.intValue());
        case LONG:
            return new Long(left.longValue() + right.longValue());
        default:
            return new Double(left.doubleValue() + right.doubleValue());
        }
    }

    protected Number minus(Number left, Number right) {
        switch (numberType(left, right)) {
        case INTEGER:
            return new Integer(left.intValue() - right.intValue());
        case LONG:
            return new Long(left.longValue() - right.longValue());
        default:
            return new Double(left.doubleValue() - right.doubleValue());
        }
    }

    protected Number multiply(Number left, Number right) {
        switch (numberType(left, right)) {
        case INTEGER:
            return new Integer(left.intValue() * right.intValue());
        case LONG:
            return new Long(left.longValue() * right.longValue());
        default:
            return new Double(left.doubleValue() * right.doubleValue());
        }
    }

    protected Number divide(Number left, Number right) {
        return new Double(left.doubleValue() / right.doubleValue());
    }

    protected Number mod(Number left, Number right) {
        return new Double(left.doubleValue() % right.doubleValue());
    }

    private int numberType(Number left, Number right) {
        if (isDouble(left) || isDouble(right)) {
            return DOUBLE;
        } else if (left instanceof Long || right instanceof Long) {
            return LONG;
        } else {
            return INTEGER;
        }
    }

    private boolean isDouble(Number n) {
        return n instanceof Float || n instanceof Double;
    }

    protected Number asNumber(Object value) {
        if (value instanceof Number) {
            return (Number)value;
        } else {
            throw new RuntimeException("Cannot convert value: " + value + " into a number");
        }
    }

    public Object evaluate(MessageEvaluationContext message) throws JMSException {
        Object lvalue = left.evaluate(message);
        if (lvalue == null) {
            return null;
        }
        Object rvalue = right.evaluate(message);
        if (rvalue == null) {
            return null;
        }
        return evaluate(lvalue, rvalue);
    }

    /**
     * @param lvalue
     * @param rvalue
     * @return
     */
    protected abstract Object evaluate(Object lvalue, Object rvalue);

}

Other ActiveMQ examples (source code examples)

Here is a short list of links related to this ActiveMQ ArithmeticExpression.java source code file:

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