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Programming Articles
Page 1529 of 2547
Can 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 ...
Read MoreLongStream generate() method in Java
The generate() method of the LongStream class returns an infinite sequential unordered stream where each element is generated by the provided LongSupplier.The syntax is as follows:static LongStream generate(LongSupplier s)Here, s is the LongSupplier for generate elements. The LongSupplier is the supplier of long-valued results.To use the LongStream class in Java, import the following package:import java.util.stream.LongStream;The following is an example to implement LongStream generate() method in Java −Exampleimport java.util.stream.LongStream; public class Demo { public static void main(String[] args){ LongStream longStream = LongStream.generate(() -> { return (long)(Math.random() * 100); }); System.out.println("Unordered ...
Read MoreCan we create an object for an interface in java?
No, you cannot instantiate an interface. Generally, it contains abstract methods (except default and static methods introduced in Java8), which are incomplete.Still if you try to instantiate an interface, a compile time error will be generated saying “MyInterface is abstract; cannot be instantiated”.In the following example we an interface with name MyInterface and a class with name InterfaceExample.In the interface we have an integer filed (public, static and, final) num and abstract method demo().From the class we are trying to − create an object of the interface and print the num value.Exampleinterface MyInterface{ public static final int num = ...
Read MoreCollectors averagingDouble() method in Java 8
The averagingDouble() method of the Collectors class in Java 8 returns a Collector that is the arithmetic mean of a double-valued function applied to the input elements.The syntax is as follows −public static Collector averagingDouble(ToDoubleFunction
Read MoreMethods Accepting a Variable Number of objects in Java
A method that accepts a variable number of Object arguments in Java is a form of variable length arguments(Varargs). These can have zero or multiple Object type arguments.A program that demonstrates this is given as follows:Examplepublic class Demo { public static void Varargs(Object... args) { System.out.println("Number of Object arguments are: " + args.length); System.out.println("The Object argument values are: "); for (Object i : args) System.out.println(i); } public static void main(String args[]) { Varargs("Apples", "4", "All"); Varargs("Half of", 3, "is", ...
Read MoreLongStream rangeClosed() method in Java
The rangeClosed() method of the LongStream class in Java returns a sequential ordered LongStream from startInclusive to endExclusive by an incremental step of 1. This is inclusive of the initial element and the last element.The syntax is as follows −static LongStream rangeClosed(long startInclusive, long endExclusive)Here, startInclusive is the first value, whereas the endExclusive is the last.To use the LongStream class in Java, import the following package −import java.util.stream.LongStream;The following is an example to implement LongStream rangeClosed() method in Java −Exampleimport java.util.stream.LongStream; public class Demo { public static void main(String[] args) { ...
Read MoreCan we declare final variables without initialization in java?
In Java, final is the access modifier which can be used with a filed class and a method.When a method if final it cannot be overridden.When a variable is final its value cannot be modified further.When a class is final it cannot be extended.Declaring final variable without initializationIf you declare a final variable later on you cannot modify or, assign values to it. Moreover, like instance variables, final variables will not be initialized with default values.Therefore, it is mandatory to initialize final variables once you declare them.Still, if you try to declare final variables without initialization that will generate a ...
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