docs/_docs/code-snippets/java/src/main/java/org/apache/ignite/snippets/ComputeTaskExample.java

/*
 * 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
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package org.apache.ignite.snippets;

import java.util.ArrayList;
import java.util.List;

import org.apache.ignite.Ignite;
import org.apache.ignite.IgniteCompute;
import org.apache.ignite.Ignition;
import org.apache.ignite.compute.ComputeJob;
import org.apache.ignite.compute.ComputeJobAdapter;
import org.apache.ignite.compute.ComputeJobResult;
import org.apache.ignite.compute.ComputeTaskSplitAdapter;

//tag::compute-task-example[]
public class ComputeTaskExample {
    public static class CharacterCountTask extends ComputeTaskSplitAdapter<String, Integer> {
        // 1. Splits the received string into words
        // 2. Creates a child job for each word
        // 3. Sends the jobs to other nodes for processing.
        @Override
        public List<ComputeJob> split(int gridSize, String arg) {
            String[] words = arg.split(" ");

            List<ComputeJob> jobs = new ArrayList<>(words.length);

            for (final String word : words) {
                jobs.add(new ComputeJobAdapter() {
                    @Override
                    public Object execute() {
                        System.out.println(">>> Printing '" + word + "' on from compute job.");

                        // Return the number of letters in the word.
                        return word.length();
                    }
                });
            }

            return jobs;
        }

        @Override
        public Integer reduce(List<ComputeJobResult> results) {
            int sum = 0;

            for (ComputeJobResult res : results)
                sum += res.<Integer>getData();

            return sum;
        }
    }

    public static void main(String[] args) {

        Ignite ignite = Ignition.start();

        IgniteCompute compute = ignite.compute();

        // Execute the task on the cluster and wait for its completion.
        int cnt = compute.execute(CharacterCountTask.class, "Hello Grid Enabled World!");

        System.out.println(">>> Total number of characters in the phrase is '" + cnt + "'.");
    }
}

//end::compute-task-example[]