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Articles on Trending Technologies
Technical articles with clear explanations and examples
Insert all elements of other Collection to Specified Index of Java ArrayList
The elements of a Collection can be inserted at the specified index of the ArrayList using the method java.util.ArrayList.addAll(). This method has two parameters i.e. the specific index at which to start inserting the Collection elements in the ArrayList and the Collection itself.If there is an element already present at the index specified by ArrayList.addAll() then that element and all subsequent elements are shifted to the right to make the space for the Collection elements in the ArrayList.A program that demonstrates this is given as follow.Exampleimport java.util.ArrayList; import java.util.Vector; public class Demo { public static void main(String[] args) { ...
Read MoreIntStream average() method in Java
The average() method of the IntStream class in Java returns an OptionalDouble describing the arithmetic mean of elements of this stream, or an empty optional if this stream is empty. It gets the average of the elements of the stream.The syntax is as followsOptionalDouble average()Here, OptionalDouble is a container object which may or may not contain a double value.Create an IntStream with some elementsIntStream intStream = IntStream.of(15, 13, 45, 18, 89, 70, 76, 56);Now, get the average of the elements of the streamOptionalDouble res = intStream.average();The following is an example to implement IntStream average() method in Java. The isPresent() method ...
Read MoreModify the value associated with a given key in Java HashMap
First, create a HashMap and add elements to it −// Create a hash map HashMap hm = new HashMap(); // Put elements to the map hm.put("Bag", new Integer(1100)); hm.put("Sunglasses", new Integer(2000)); hm.put("Frames", new Integer(800)); hm.put("Wallet", new Integer(700)); hm.put("Belt", new Integer(600));Now, to modify the value associated with a given key, use the put() method. Here, we are modifying the value for the key “Frames” −hm.put("Frames", "900");The following is an example to modify the value associated with a given key −Exampleimport java.util.*; public class Demo { public static void main(String args[]) { // ...
Read MoreCreate a TreeMap in Java and add key-value pairs
A TreeMap cannot contain duplicate keys. TreeMap cannot contain the null key. However, It can have null values.Let us first see how to create a TreeMap −TreeMap m = new TreeMap();Add some elements in the form of key-value pairs −m.put(1, "India"); m.put(2, "US"); m.put(3, "Australia"); m.put(4, "Netherlands"); m.put(5, "Canada");The following is an example to create a TreeMap and add key-value pairs −Exampleimport java.util.*; public class Demo { public static void main(String args[]) { TreeMap m = new TreeMap(); m.put(1, "India"); m.put(2, "US"); m.put(3, "Australia"); ...
Read MoreDisplay File class constants in Java
The java.io.File class has display constants File.separatorChar and File.pathSeparatorChar mainly. The File.separatorChar is ‘/’ and the File.pathSeparatorChar is ‘:’ for Unix.A program that demonstrates this is given as follows −Exampleimport java.io.File; public class Demo { public static void main(String[] args) { try { System.out.println("File.pathSeparatorChar = " + File.pathSeparatorChar); System.out.println("File.separatorChar = " + File.separatorChar); } catch(Exception e) { e.printStackTrace(); } } }The output of the above program is as follows −OutputFile.pathSeparatorChar = : File.separatorChar = /Now let us ...
Read MoreLongStream parallel() method in Java
The parallel() method of the LongStream class in Java returns an equivalent stream that is parallel.The syntax is as follows:LongStream parallel()To use the LongStream class in Java, import the following packageExampleimport java.util.stream.LongStream;The following is an example to implement LongStream parallel() method in Java:import java.util.stream.LongStream; public class Demo { public static void main(String[] args) { LongStream longStream = LongStream.range(10L, 20L); System.out.println("Parallel LongStream = "); longStream.parallel().forEach(System.out::println); } }outputParallel LongStream = 16 15 10 17 11 13 12 19 18 14
Read MoreCan we write any statements between try, catch and finally blocks in Java?
No, we cannot write any statements in between try, catch and finally blocks and these blocks form one unit. The functionality of try keyword is to identify an exception object and catch that exception object and transfer the control along with the identified exception object to the catch block by suspending the execution of the try block. The functionality of the catch block is to receive the exception class object that has been sent by the try and catch that exception class object and assigns that exception class object to the reference of the corresponding exception class defined in the catch block. The finally blocks are ...
Read MoreJava Program to remove a key from a TreeMap only if it is associated with a given value
Use the remove() method to remove a key from a TreeMap only if it is associated with a given value. Let us first create a TreeMap and add some elements −TreeMap m = new TreeMap(); m.put(1, "India"); m.put(2, "US"); m.put(3, "Australia"); m.put(4, "Netherlands"); m.put(5, "Canada");To remove a key, set the key and the associated value here. If the associate value exists, then the key will get removed −m.remove(3, "Australia")The following is an example to remove a key from a TreeMap only if it is associated with a given value −Exampleimport java.util.*; public class Demo { public static void main(String ...
Read MoreList the file system roots in Java
The method java.io.File.listRoots() is used to list the file system roots in Java. This method requires no parameters. It returns the available file system roots in the form of an array of file objects and if the file system roots cannot be determined, it returns null.A program that demonstrates this is given as follows −Exampleimport java.io.File; public class Demo { public static void main(String[] args) { File[] roots = File.listRoots(); try { for(File r : roots) { System.out.println(r); } ...
Read MoreDuration ZERO field in Java
The ZERO field sets the duration to zero in the Duration class in Java. This field is quite the same as the null value in different data types in Java.A program that demonstrates the ZERO field is given as follows −Exampleimport java.time.Duration; public class Demo { public static void main(String[] args) { Duration d = Duration.ZERO; boolean flag = d.isZero(); System.out.println("The duration is: " + d); if(flag) System.out.println("The above duration is of zero length"); else System.out.println("The ...
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