Queue queue1 = new LinkedList(); Queue queue2 = new PriorityQueue(); class Test { public static void main(String[] args) { Queue<String> queue = new LinkedList(); queue.offer(“Steve”); queue.offer(“Megan”); queue.offer(“Ryan”); queue.offer(“Melissa”); System.out.println(queue); } } Output: [Steve, Megan, Ryan, Melissa] We can also use the add(Object o) method to add elements to the Queue. In this example, we will…
Read More Queue in JavaHashMap<K, V> map = new HashMap<>(); Map<Integer, String> map = new HashMap<>(); class Test { public static void main(String[] args) { Map<Integer, String> map = new HashMap<>(); map.put(1, “Java”); map.put(7, “Python”); map.put(10, “Ruby”); map.put(3, “Kotlin”); System.out.println(map); } } Output: {1=Java, 3=Kotlin, 7=Python, 10=Ruby} class Test { public static void main(String[] args) { Map<Integer, String> map…
Read More Map in JavaHashSet<String> set = new HashSet<>(); Set<String> set = new HashSet<>(); class Test { public static void main(String[] args) { Set<String> set = new HashSet<>(); set.add(“Java”); set.add(“Kotlin”); set.add(“Python”); set.add(“Ruby”); System.out.println(set); } } Output: [Java, Ruby, Kotlin, Python] class Test { public static void main(String[] args) { Set<String> set = new HashSet<>(); set.add(“Kotlin”); set.add(“Java”); set.add(“Ruby”); set.add(“Python”); Set<String>…
Read More Set in JavaLinkedList<String> list = new LinkedList<>(); List<Integer> list = new LinkedList<>(); class Test { public static void main(String[] args) { List<String> list = new LinkedList<>(); list.add(“Steve”); list.add(“Megan”); list.add(“Melissa”); list.add(“Ryan”); System.out.println(list); } } Output: [Steve, Megan, Melissa, Ryan] class Test { public static void main(String[] args) { List<String> list = new LinkedList<>(); list.add(“Steve”); list.add(“Megan”); list.add(“Melissa”); list.add(“Ryan”); List<String>…
Read More LinkedList in JavaArrayList<String> list = new ArrayList<>(); List<Integer> list = new ArrayList<>(); class Test { public static void main(String[] args) { List<String> list = new ArrayList<>(); list.add(“Steve”); list.add(“Megan”); list.add(“Melissa”); list.add(“Ryan”); System.out.println(list); } } Output: [Steve, Megan, Melissa, Ryan] Using the addAll() method, we can add all the elements of an existing list to the newly created…
Read More ArrayList in JavaIterator<T> iterator() Method Description public boolean add(E e) It is used to insert an element in this collection. public boolean addAll(Collection<? extends E> c) It is used to insert the specified collection elements in the invoking collection. public boolean remove(Object element) It is used to delete an element from the collection.…
Read More Java Collectionsclass Test { public static void main(String[] args) { for (int i = 0; i < 10; i++) { System.out.println(“Value:” + i); if (i == 3) { break; // terminate the loop if condition is met } } System.out.println(“Code after the loop…”); } } Output: Value:0 Value:1 Value:2 Value:3 Code after the loop… In…
Read More Java break and continue statementswhile(expression) { // body of the loop } class Test { public static void main(String[] args) { int data = 5; while (data < 10) { System.out.println(“Data: ” + data); data++; } System.out.println(“Code after the while loop…”); } } Output: Data: 5 Data: 6 Data: 7 Data: 8 Data: 9 Code after the while loop……
Read More Java while and do-while Loopsfor (value initialization; testing expression; updating the value) { // body of the loop } class Test { public static void main(String[] args) { // count value exactly 5 times for(int i = 1; i<=5; i++) { System.out.println(“Count: ” + i); } } } Output: Count: 1 Count: 2 Count: 3 Count: 4 Count: 5…
Read More Java For Loopswitch (expression) { case constant: // switch block 1… break; case constant: // switch block 2… break; default: // default switch block … ; } class Test { public static void main(String[] args) { String color = “blue”; switch (color) { case “white”: // if it is white, execute this block of code System.out.println(“The color…
Read More Java switch Statementclass Test { public static void main(String[] args) { int a = 10; int b = 5; if (a > b) { // if true, enter the if code block System.out.println(“a is greater than b”); } System.out.println(“Rest of the code …”); } } Output: a is greater than b Rest of the code … …
Read More Java if-else Statementclass Test { public static void main(String[] args) { String str = “ALEGRUTECHBLOG”; String strInLowerCase = str.toLowerCase(); System.out.println(strInLowerCase); } } Output: alegrutechblog toUpperCase() Converts all of the characters in this String to the upper case using the rules of the default locale. class Test { public static void main(String[] args) { String str…
Read More Working With Strings in Java – Part 2class Test { public static void main(String[] args) { String str = “alegru”; char c = str.charAt(2); System.out.println(c); } } Output: e class Test { public static void main(String[] args) { String str = “alegru”; int index = str.indexOf(‘l’); System.out.println(index); } } Output: 1 class Test { public static void main(String[] args) { String str…
Read More Working With Strings in Java – Part 1String str = “Hello”; String str = new String(“Hello”); class Test { public static void main(String[] args) { String str1 = “Hello”; String str2 = “Hello”; String str3 = new String(“Hello”); System.out.println(str1 == str2); System.out.println(str1 == str3); } } Output: true false Here: We create str1 by assigning it a String literal. Then, that…
Read More Java String Tutorialimport java.util.Arrays; class Test { public static void main(String[] args) { String[] names = {“John”, “Steve”, “Melissa”, “Maria”}; System.out.println(Arrays.toString(names)); } } Output: [John, Steve, Melissa, Maria] copyOf(type [] a, int n) Returns a new copy of the array, which consists of the first n of its elements. import java.util.Arrays; class Test { public static…
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