In SQL, the GROUP BY statement returns the set of records having the same value in particular criteria. For example, you have a table that contains student information, each student coming from a different country. Use the GROUP BY statement according to national criteria, you… Read More
This method is supported since Java 9. This method is used to create a new Stream object from an Optional object in Java. If the Optional object contains a value, this method will return the Stream object containing that value, otherwise, it returns an empty… Read More
In Java 8, the iterate() method has been introduced and it has only two parameters and will help us to create an infinite stream. Content:
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public static<T> Stream<T> iterate(final T seed, final UnaryOperator<T> f) |
Example:
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package com.huongdanjava.javastream; import java.util.stream.Stream; public class Example { public static void main(String[] args) { Stream.iterate(1, i -> i + 1).forEach(System.out::println); } } |
When running the above example, you will see that a Stream object contains endless numbers beginning at… Read More
This method was added from Java 9.
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static<T> Stream<T> ofNullable(T t) |
This method will return the Stream object of an element in case this element is not null; if it is null, it returns an empty Stream. Example:
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package com.huongdanjava.javaexample; import java.util.stream.Stream; public class Example { public static void main(String[] args) { String s = null; Stream.ofNullable(s).forEach(System.out::println); } } |
When you run the above code, it will print… Read More
This method was added from Java 9.
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default Stream<T> dropWhile(Predicate<? super T> predicate) |
This method also has the parameter Predicate interface and its function is the opposite of the takeWhile() method. This method also passes each element in your Stream object from left to right and ignores all elements that… Read More
This method was added from Java 9.
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default Stream<T> takeWhile(Predicate<? super T> predicate) |
The parameter of this method is the Predicate interface and this method takes the elements in your Stream object from left to right, until the condition of the Predicate object is no longer fulfilled. Example:
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package com.huongdanjava.javastream; import java.util.stream.Stream; public class Example { public static void main(String[] args) { Stream.of(1,2,3,4,5,6,7,8,9,10) .takeWhile(i -> i < 5) .forEach(System.out::println); } } |
In… Read More
When working with Stream in Java, sometime we can have a Stream with datatype of a List, Set or Array of object. For example:
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List<String> students1 = new ArrayList<>(); students1.add("Khanh"); List<String> students2 = new ArrayList<>(); students2.add("Thanh"); students2.add("Dung"); List<List<String>> students = Arrays.asList(students1, students2); Stream<List<String>> stream = students.stream(); |
Here, we have List of List of String object and when convert into Stream object, we have Stream of List… Read More
To filter a Map using Stream and Lambda Expression in Java, we will use the filter() method of Stream object which will be retrieved from Entry object of Map object with Lambda Expression as filter a List. How is it in details? Let learn together in… Read More
In this tutorial, I will show you how to order elements in a Map object using the Stream object and the Collectors object in Java by key and by value. For example, we have a Map object like this:
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Map<String, Integer> studentMap = new HashMap<>(); studentMap.put("Khanh", 31); studentMap.put("Thanh", 25); studentMap.put("Dung", 35); |
Prior to Java 8, to… Read More
Stream is a new Java object, was introduced from Java 8. It helps us can manipulate on collections and arrays easier and more efficient. So what is it? In this article, I will introduce with you all about the Stream in Java. First, consider the… Read More
