Java tutorial
/* * Copyright 2016 Crown Copyright * * 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 uk.gov.gchq.gaffer.function.aggregate; import org.apache.commons.lang.builder.EqualsBuilder; import org.apache.commons.lang.builder.HashCodeBuilder; import org.apache.commons.lang.builder.ToStringBuilder; import uk.gov.gchq.gaffer.function.SimpleAggregateFunction; import uk.gov.gchq.gaffer.function.annotation.Inputs; import uk.gov.gchq.gaffer.function.annotation.Outputs; /** * An <code>ComparableMin</code> is a {@link SimpleAggregateFunction} that takes in * {@link Comparable}s and calculates the minimum comparable. It assumes that all the input comparables * are compatible and can be compared against each other. */ @Inputs(Comparable.class) @Outputs(Comparable.class) public class ComparableMin extends SimpleAggregateFunction<Comparable> { private Comparable aggregate; @Override public void init() { aggregate = null; } @Override protected Comparable _state() { return aggregate; } @Override protected void _aggregate(final Comparable input) { if (aggregate == null || input.compareTo(aggregate) < 0) { aggregate = input; } } @Override public ComparableMin statelessClone() { final ComparableMin min = new ComparableMin(); min.init(); return min; } @Override public boolean equals(final Object o) { if (this == o) { return true; } if (o == null || getClass() != o.getClass()) { return false; } final ComparableMin that = (ComparableMin) o; return new EqualsBuilder().append(inputs, that.inputs).append(outputs, that.outputs) .append(aggregate, that.aggregate).isEquals(); } @Override public int hashCode() { return new HashCodeBuilder(17, 37).append(inputs).append(outputs).append(aggregate).toHashCode(); } @Override public String toString() { return new ToStringBuilder(this).append("inputs", inputs).append("outputs", outputs) .append("aggregate", aggregate).toString(); } }