The mapToInt()
method in Java, part of the java.util.stream.DoubleStream
interface, is used to apply a given function to each element of the stream, producing an IntStream
with the results of the applied function. This method is useful when you need to transform the elements of a DoubleStream
into int
values.
Table of Contents
- Introduction
mapToInt()
Method Syntax- Understanding
mapToInt()
- Examples
- Basic Usage
- Using
mapToInt()
with Custom Transformation
- Real-World Use Case
- Conclusion
Introduction
The mapToInt()
method returns an IntStream
consisting of the results of applying a given function to the elements of the original DoubleStream
. This method is an intermediate operation, meaning it returns a new stream and does not modify the original stream.
mapToInt() Method Syntax
The syntax for the mapToInt()
method is as follows:
IntStream mapToInt(DoubleToIntFunction mapper)
Parameters:
mapper
: ADoubleToIntFunction
that represents the function to be applied to each element of the stream.
Returns:
- An
IntStream
consisting of the results of applying the given function to the elements of the originalDoubleStream
.
Throws:
- This method does not throw any exceptions.
Understanding mapToInt()
The mapToInt()
method allows you to transform the elements of a DoubleStream
by applying a specified function to each element. The resulting stream contains the transformed elements as int
values, preserving the order of the original stream.
Examples
Basic Usage
To demonstrate the basic usage of mapToInt()
, we will create a DoubleStream
and use mapToInt()
to convert each element to its integer part.
Example
import java.util.stream.DoubleStream;
import java.util.stream.IntStream;
public class MapToIntExample {
public static void main(String[] args) {
DoubleStream doubleStream = DoubleStream.of(1.1, 2.2, 3.3, 4.4, 5.5);
// Apply a function to convert each element to its integer part
IntStream intStream = doubleStream.mapToInt(n -> (int) n);
// Print the resulting IntStream
intStream.forEach(System.out::println);
}
}
Output:
1
2
3
4
5
Using mapToInt()
with Custom Transformation
This example shows how to use mapToInt()
to transform a DoubleStream
into an IntStream
by applying a custom transformation. In this case, we will multiply each element by 10 and convert it to an integer.
Example
import java.util.stream.DoubleStream;
import java.util.stream.IntStream;
public class CustomTransformationExample {
public static void main(String[] args) {
DoubleStream doubleStream = DoubleStream.of(1.1, 2.2, 3.3, 4.4, 5.5);
// Apply a custom function to multiply each element by 10 and convert to int
IntStream intStream = doubleStream.mapToInt(n -> (int) (n * 10));
// Print the resulting IntStream
intStream.forEach(System.out::println);
}
}
Output:
11
22
33
44
55
Real-World Use Case
Converting Sensor Readings to Integer Units
In real-world applications, the mapToInt()
method can be used to convert sensor readings from double values to integer units for further processing or storage.
Example
import java.util.stream.DoubleStream;
import java.util.stream.IntStream;
public class SensorDataConversionExample {
public static void main(String[] args) {
DoubleStream sensorData = DoubleStream.of(25.3, 26.7, 24.8, 27.5, 30.1);
// Convert the sensor readings to integer units
IntStream intSensorData = sensorData.mapToInt(reading -> (int) reading);
// Print the converted sensor readings
intSensorData.forEach(intReading -> System.out.println("Integer sensor reading: " + intReading));
}
}
Output:
Integer sensor reading: 25
Integer sensor reading: 26
Integer sensor reading: 24
Integer sensor reading: 27
Integer sensor reading: 30
Conclusion
The DoubleStream.mapToInt()
method is used to apply a given function to each element of the stream, producing an IntStream
with the results of the applied function. This method is particularly useful for transforming the elements of a DoubleStream
into int
values. By understanding and using this method, you can efficiently manage and manipulate streams of double values in your Java applications.
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