org.jboss.marshalling.Pair Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* JBoss, Home of Professional Open Source.
* Copyright 2014 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* 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 org.jboss.marshalling;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.io.Externalizable;
import java.io.ObjectOutput;
import java.io.IOException;
import java.io.ObjectInput;
/**
* A serializable pair of values. There is also a specified externalizer as well, to support more efficient I/O.
*
* @param the first value type
* @param the second value type
* @apiviz.exclude
*/
@Externalize(Pair.Externalizer.class)
public final class Pair implements Serializable {
private static final long serialVersionUID = 7331975617882473974L;
private final A a;
private final B b;
@SuppressWarnings({ "InstanceVariableMayNotBeInitializedByReadObject" })
private final transient int hashCode;
private static final FieldSetter setter = FieldSetter.get(Pair.class, "hashCode");
/**
* Create a new instance.
*
* @param a the first value
* @param b the second value
*/
public Pair(final A a, final B b) {
this.a = a;
this.b = b;
hashCode = hashCode(a, b);
}
/**
* Calculate the combined hash code of two objects.
*
* @param a the first object
* @param b the second object
* @return the combined hash code
*/
private static int hashCode(final Object a, final Object b) {
return (a == null ? 0 : a.hashCode()) * 1319 + (b == null ? 0 : b.hashCode());
}
/**
* Get the first value.
*
* @return the first value
*/
public A getA() {
return a;
}
/**
* Get the second value.
*
* @return the second value
*/
public B getB() {
return b;
}
/**
* Reinitialize the object and set the hash code.
*
* @param ois the object input stream
* @throws IOException if an I/O error occurs while reading the default fields
* @throws ClassNotFoundException if a class isn't found while reading the default fields
*/
private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
ois.defaultReadObject();
setter.setInt(this, hashCode(a, b));
}
/**
* Return the combined hash code of the two argument objects.
*
* @return the combined hash code
*/
public int hashCode() {
return hashCode;
}
/**
* Determine if this pair equals another. A pair is equal to another pair if both members are equal.
*
* @param other the other pair
* @return {@code true} if they are equal, {@code false} otherwise
*/
public boolean equals(final Object other) {
return (other instanceof Pair) ? equals((Pair) other) : false;
}
/**
* Determine if this pair equals another. A pair is equal to another pair if both members are equal.
*
* @param other the other pair
* @return {@code true} if they are equal, {@code false} otherwise
*/
public boolean equals(final Pair other) {
if (other == null) {
return false;
}
final Object a = this.a;
final Object othera = other.a;
final Object b = this.b;
final Object otherb = other.b;
return (a == othera || a != null && a.equals(othera)) &&
(b == otherb || b != null && b.equals(otherb));
}
/**
* Get a string representation of this pair.
*
* @return the string representation
*/
public String toString() {
final StringBuilder builder = new StringBuilder();
builder.append("Pair (").append(a).append(", ").append(b).append(')');
return builder.toString();
}
/**
* Create a new instance.
*
* @param a the first value
* @param b the second value
* @param the first value type
* @param the second value type
* @return the new instance
*/
public static Pair create(A a, B b) {
return new Pair(a, b);
}
/**
* An externalizer for {@link Pair} instances.
* @apiviz.exclude
*/
public static final class Externalizer implements org.jboss.marshalling.Externalizer, Externalizable {
private static final long serialVersionUID = 930391108343329811L;
private static final Externalizer instance = new Externalizer();
/**
* Get the single instance. Though multiple instances can be created using the public constructor, only a single
* instance need be used in practice since this class maintains no internal state.
*
* @return the instance
*/
public static Externalizer getInstance() {
return instance;
}
/** {@inheritDoc} */
public void writeExternal(final Object subject, final ObjectOutput output) throws IOException {
output.writeObject(((Pair)subject).a);
output.writeObject(((Pair)subject).b);
}
/** {@inheritDoc} */
public Object createExternal(final Class subjectType, final ObjectInput input) throws IOException, ClassNotFoundException {
return create(input.readObject(), input.readObject());
}
/** {@inheritDoc} */
public void writeExternal(final ObjectOutput out) {
}
/** {@inheritDoc} */
public void readExternal(final ObjectInput in) {
}
/**
* Resolve the object to the single externalizer instance.
*
* @return the instance
*/
protected Object readResolve() {
return instance;
}
}
}