how to convert DataSource in ExecutionEnvironment to DataStream in StreamExecutionEnvironment in apache flink

To convert a DataSource in ExecutionEnvironment to DataStream in StreamExecutionEnvironment in Apache Flink, you can follow these steps:

1. Create an ExecutionEnvironment object and load the data from a file or a collection. For example:

ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
DataSet<String> input = env.readTextFile("path/to/file");

2. Create a StreamExecutionEnvironment object.

StreamExecutionEnvironment streamEnv = StreamExecutionEnvironment.getExecutionEnvironment();

3. Convert the DataSet to DataStream by calling the toDataStream() method.

DataStream<String> stream = input.toDataStream(streamEnv);

4. You can now apply transformations on the DataStream, like filtering, mapping, aggregating, etc.

DataStream<Integer> numbers = stream.flatMap(new FlatMapFunction<String, Integer>() {
    @Override
    public void flatMap(String value, Collector<Integer> out) throws Exception {
        String[] tokens = value.split(",");
        for (String token : tokens) {
            out.collect(Integer.parseInt(token));
        }
    }
});

DataStream<Integer> filteredNumbers = numbers.filter(new FilterFunction<Integer>() {
    @Override
    public boolean filter(Integer value) throws Exception {
        return value > 0;
    }
});

DataStream<Integer> sum = filteredNumbers.keyBy(0).sum(1);

5. Finally, you can execute the stream job by calling the execute() method.

sum.print();
streamEnv.execute("My Streaming Job");