Below is a simple Flink word count example. Note that using the Dataset API is not rceommended for production environments; this example is for educational purposes only.

Maven Configuration

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>simple-demo</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>flink</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <flink.version>1.17.0</flink.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-streaming-java</artifactId>
            <version>${flink.version}</version>
        </dependency>

        <dependency>
            <groupId>org.apache.flink</groupId>
            <artifactId>flink-clients</artifactId>
            <version>${flink.version}</version>
        </dependency>
    </dependencies>

</project>

Task Code

package com.example.flink.job;

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.operators.AggregateOperator;
import org.apache.flink.api.java.operators.DataSource;
import org.apache.flink.api.java.operators.FlatMapOperator;
import org.apache.flink.api.java.operators.UnsortedGrouping;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.util.Collector;

/**
 * Example of implementing word count using the Dataset API (not recommended for production)
 */
public class WordCountExample {
    public static void main(String[] args) throws Exception {
        // Create execution environment
        ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        // Read input data from file
        DataSource<String> lines = env.readTextFile("E:\\code-opensource\\simple-demo\\flink\\input\\word.txt");

        // Split and transform into (word, 1)
        FlatMapOperator<String, Tuple2<String, Integer>> wordPairs = lines.flatMap(new FlatMapFunction<String, Tuple2<String, Integer>>() {
            @Override
            public void flatMap(String value, Collector<Tuple2<String, Integer>> out) throws Exception {
                String[] words = value.split(" ");
                for (String word : words) {
                    Tuple2<String, Integer> pair = Tuple2.of(word, 1);
                    out.collect(pair);
                }
            }
        });

        // Group by word
        UnsortedGrouping<Tuple2<String, Integer>> groupedWords = wordPairs.groupBy(0);

        // Sum counts
        AggregateOperator<Tuple2<String, Integer>> summedCounts = groupedWords.sum(1);

        // Output results
        summedCounts.print();
    }
}

Output Result

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