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Java Articles
Page 104 of 450
Get the list of all the public fields in Java
An array of field objects is returned by the method java.lang.Class.getFields(). These field objects include the accessible public fields of the class that is represented by the class object.Also, the getFields() method returns a zero length array if the class or interface has no public fields that are accessible or if a primitive type, array class or void is represented in the Class object.A program that demonstrates this is given as follows −Exampleimport java.lang.reflect.*; public class Demo { public static void main(String[] argv) throws Exception { Class c = java.lang.Thread.class; Field[] fields = ...
Read MoreRemoving a Preference from a Preference Node in Java
In order to remove a preference from a preference node in Java, we use the remove() method. The remove method() removes all the values associated with the specified key in the preference node.Declaration − The java.util.prefs.Preferences.remove() method is declared as follows −public abstract void remove (String key)where key is the key whose preference is to be removedThe remove methods throws the following exceptions −NullPointerExceptionThis exception occurs when the key is nullIllegalStateExceptionThis exception is thrown when the ancestor node is removed by the removeNode() method.Let us see a program to remove the preference from a preference node −Exampleimport java.util.prefs.Preferences; public class ...
Read MoreDetermine if a Preference Node exists in Java
In order to determine the existence a preference node in Java, we use the nodeExists() method. The nodeExists() method returns a boolean value. It returns true when the specified preference node exists in the same tree as this node.Declaration − The java.util.prefs.Preferences.remove() method is declared as follows −public abstract boolean nodeExists(String pathname)throws BackingStoreExceptionwhere pathname is the path name of the node whose existence needs to be determined.Let us see a program to determine if a preference node exists in Java −Exampleimport java.util.prefs.Preferences; public class Example { public static void main(String[] args) throws Exception { boolean exist ...
Read MoreDisplay the maximum amount of memory in Java
In order to display the maximum amount of memory in Java, we use the maxMemory() method. It is a method of the java.lang.Runtime Class. It returns the maximum amount of memory that the Java Virtual Machine will try to use.Declaration − The java.lang.Runtime.maxMemory() method is declared as follows −public long maxMemory()Let us see a program to display the maximum amount of memory in Java −Examplepublic class Example { public static void main(String[] args) { // print statement at the start of the program System.out.println("Start..."); // displays the maximum memory ...
Read MoreDisplay the amount of free memory in the Java Virtual Machine
In order to display the amount of free memory in the Java Virtual Machine, we use the freeMemory() method. It is a method of the java.lang.Runtime Class. It returns the amount of free memory in the Java Virtual Machine. If we call the gc method, there is a possibility of increase of free memory.Declaration − The java.lang.Runtime.freeMemory() method is declared as follows −public long freeMemory()Let us see a program to display the amount of free memory in the Java Virtual Machine −Examplepublic class Example { public static void main(String[] args) { // print statement at the ...
Read MoreGet number of available processors in Java
In order to get the number of available processors in Java, we use the availableProcessors() method. The java.lang.Runtime.availableProcessors() method returns the number of processors which are available to the Java virtual machine. This number may vary during a particular call of the virtual machine.Declaration − The java.lang.Runtime.availableProcessors() method is declared as follows −public int availableProcessors()Let us see a program to get the number of available processors in Java −Examplepublic class Example { public static void main(String[] args) { // print statement at the start of the program System.out.println("Start..."); System.out.print("Number of ...
Read MoreGenerate Random Integer Numbers in Java
In order to generate Random Integer Numbers in Java, we use the nextInt() method of the java.util.Random class. This returns the next random integer value from this random number generator sequence.Declaration − The java.util.Random.nextInt() method is declared as follows −public int nextInt()Let us see a program to generate random integer numbers in Java −Exampleimport java.util.Random; public class Example { public static void main(String[] args) { Random rd = new Random(); // creating Random object System.out.println(rd.nextInt()); } }Output27100093Note - The output might vary on Online Compilers.
Read MoreGenerate Random bytes in Java
In order to generate random bytes in Java, we use the nextBytes() method. The java.util.Random.nextBytes() method generates random bytes and provides it to the user defined byte array.Declaration − The java.util.Random.nextBytes() method is declared as follows −public void nextBytes(byte[] bytes)where bytes is the byte array.Let us see a program to generate random bytes in Java −Exampleimport java.util.Random; public class Example { public static void main(String[] args) { Random rd = new Random(); byte[] arr = new byte[7]; rd.nextBytes(arr); System.out.println(arr); } }Output[B@15db9742Note − The output might vary ...
Read MoreRoll a six-sided die 6000 times in Java
In order to roll a six sided die 6000 times in Java, we need to the nextInt() statement with decision making statements.The nextInt() method returns the next random integer value from this random number generator sequence.Declaration − The java.util.Random.nextInt() method is declared as follows −public int nextInt()Let us see a program to roll a six sided die 6000 times −Exampleimport java.util.Random; public class Example { public static void main(String args[]) { Random rd = new Random(); // random number generator int freq[] = new int[6]; // creating an array to compute frequency of ...
Read MoreConvert a Queue to a List in Java
In order to convert a Queue to a List in Java, we can create an LinkedList and pass the Queue as an argument in the parameterized constructor of an ArrayList. This can be done as follows −Queue q = new LinkedList(); List l = new ArrayList(q);The quickest way is used to LinkedList in the first place which can be used both as a List and a Queue. This can be done as follows −Queue q = new LinkedList(); List l = (List) q;Let us see a program to convert a queue to a list −Exampleimport java.util.LinkedList; import java.util.List; import java.util.Queue; ...
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