In Java, if we remove items from a List while iterating it, it will throw java.util.ConcurrentModificationException. This article shows a few ways to solve it. Table of contents 1. java.util.ConcurrentModificationException 2. Java 8 Collection#removeIf 2.1 removeIf examples 2.2 removeIf uses Iterator 3. ListIterator example 4. Filter and Collect example 5. References P.S Tested with Java …
This tutorial shows how to use the Streaming API for XML (StAX) parser to read or parse an XML document. Table of contents 1. What is StAX 1.1 Difference between SAX and StAX? 2. StAX Cursor API and Iterator API 2.1 StAX Cursor API 2.2 StAX Iterator API 2.3 which one? Cursor or Iterator APIs? …
In Java 8, we can use StreamSupport.stream to convert an Iterator into a Stream. // Iterator -> Spliterators -> Stream Stream<String> stream = StreamSupport.stream( Spliterators.spliteratorUnknownSize( iterator, Spliterator.ORDERED) , false); Review the StreamSupport.stream method signature, it accepts a Spliterator. StreamSupport.java public static <T> Stream<T> stream(Spliterator<T> spliterator, boolean parallel) { Objects.requireNonNull(spliterator); return new ReferencePipeline.Head<>(spliterator, StreamOpFlag.fromCharacteristics(spliterator), parallel); } …
A few of Java Iterator and ListIterator examples. 1. Iterator 1.1 Get Iterator from a List or Set, and loop over it. JavaIteratorExample1a.java package com.mkyong; import java.util.Arrays; import java.util.Iterator; import java.util.List; public class JavaIteratorExample1a { public static void main(String[] args) { /* Set<Integer> set = new HashSet<>(); set.add(1); set.add(2); set.add(3); set.add(4); set.add(5); Iterator<Integer> iterator = …
In Java, there are 3 ways to loop or iterate a HashMap 1. If possible, always uses the Java 8 forEach. Map<String, String> map = new HashMap<>(); map.forEach((key, value) -> System.out.println("[Key] : " + key + " [Value] : " + value)); 2. Normal for loop in entrySet() Map<String, String> map = new HashMap<>(); for …
In Java, we can use Set.iterator().next() to get the first item from a java.util.Set JavaExample.java package com.mkyong; import java.util.HashSet; import java.util.Set; public class JavaExample { public static void main(String[] args) { Set<String> examples = new HashSet<>(); examples.add("1"); examples.add("2"); examples.add("3"); examples.add("4"); examples.add("5"); System.out.println(examples.iterator().next()); // java 8 System.out.println(examples.stream().findFirst().get()); } } Output 1 1 References Oracle doc – …