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Java Articles
Page 32 of 450
How to execute an external program like windows media player in Java?
Using the Runtime classJava provides a class named java.lang.Runtime, using this class you can interface with the current environment.The getRunTime() (static) method of this class returns a Runtime object associated with the current application.The exec() method accepts a String value representing the command to execute a process in the current environment (system) and executes it.Therefore, to execute an external application using the Runtime class −Get the run time object using the getRuntime() method.Execute the required process by passing the path of it as a String value to the exec() method.Exampleimport java.io.IOException; public class Trail { public static void main(String ...
Read MoreHow to copy a specific section of an array in Java?
Using copyOf() methodThe copyOf() method of the Arrays class (java.util package) accepts two parameters −an array (of any type).an integer value representing length.And copies the contents of the given array from starting position to given length and returns the new array.Exampleimport java.util.Arrays; public class CopyingSectionOfArray { public static void main(String[] args) { String str[] = new String[10]; //Populating the array str[0] = "Java"; str[1] = "WebGL"; str[2] = "OpenCV"; str[3] = "OpenNLP"; str[4] = "JOGL"; ...
Read MoreHow do we initialize an array within object parameters in java?
You can initialize the array variable which is declared inside the class just like any other value, either using constructor or, using the setter method.ExampleIn the following Java example, we are declaring an instance variable of array type and initializing it from the constructor.public class Student { String name; int age; String subs[]; Student(String name, int age, String subs[]){ this.name = name; this.age = age; this.subs = subs; } public void display() { System.out.println("Name: "+this.name); System.out.println("Age :"+this.age); System.out.print("Subjects: "); for(int i = 0; i < subs.length; i++) { ...
Read MoreIs it possible to check if a String only contains ASCII in java?
Using regular expressionYou can find whether a particular String value contains ASCII characters using the following regular expression −\A\p{ASCII}*\zThe matches() method of the String class accepts a regular expression and verifies whether the current string matches the given expression if so, it returns true, else it returns false.Therefore, Invoke the matches() method on the input/required string by passing the above specified regular expression as a parameter.Exampleimport java.util.Scanner; public class OnlyASCII { public static void main(String[] args) { Scanner sc = new Scanner(System.in); System.out.println("Enter a string value: "); String input = ...
Read MoreHow to parse Date from String in the format: dd/MM/yyyy to dd/MM/yyyy in java?
The java.text package provides a class named SimpleDateFormat which is used to format and parse dates in required manner (local).One of the constructors of this class accepts a String value representing the desired date format and constructors SimpleDateFormat object.The format() method of this class accepts a java.util.Date object and returns a date/time string in the format represented by the current object.Therefore, to parse a date String to another date format −Get the input date string.Convert it into java.util.Date object.Instantiate the SimpleDateFormat class by passing the desired (new) format as string to its constructor.Invoke the format() method by passing the above ...
Read MoreHow to make elements of array immutable in Java?
No, you cannot make the elements of an array immutable.But the unmodifiableList() method of the java.util.Collections class accepts an object of the List interface (object of implementing its class) and returns an unmodifiable form of the given object. The user has only read-only access to the obtained list.And the asList() method of the ArrayList class accepts an array and returns a List object.Therefore, to convert an array immutable −Obtain the desired array.Convert it into a list object using the asList() method.Pass the obtained list as a parameter to the unmodifiableList() method.Exampleimport java.util.Arrays; import java.util.Collections; import java.util.List; public class UnmodifiableExample { ...
Read MoreWhat is ArrayStoreException in Java?
When you have created an array of a particular data type with fixed size and populate it if you store a value other than its datatype an ArrayStoreException is thrown at the run time.ExampleIn the following Java program, we are creating an Integer array and trying to store a double value in it.import java.util.Arrays; public class ArrayStoreExceptionExample { public static void main(String args[]) { Number integerArray[] = new Integer[3]; integerArray[0] = 12548; integerArray[1] = 36987; integerArray[2] = 555.50; integerArray[3] = 12548; ...
Read MoreWhat is loose coupling how do we achieve it using Java?
Coupling refers to the dependency of one object type on another, if two objects are completely independent of each other and the changes done in one doesn’t affect the other both are said to be loosely coupled.You can achieve loose coupling in Java using interfaces -Exampleinterface Animal { void child(); } class Cat implements Animal { public void child() { System.out.println("kitten"); } } class Dog implements Animal { public void child() { System.out.println("puppy"); } } public class LooseCoupling { public static void main(String args[]) { Animal obj = new Cat(); obj.child(); } }Outputkitten
Read MoreHow to access a derived class member variable by an interface object in Java?
When you try to hold the super class’s reference variable with a sub class object, using this object you can access the members of the super class only, if you try to access the members of the derived class using this reference you will get a compile time error.Exampleinterface Sample { void demoMethod1(); } public class InterfaceExample implements Sample { public void display() { System.out.println("This ia a method of the sub class"); } public void demoMethod1() { System.out.println("This is demo method-1"); } public static void main(String args[]) { ...
Read MoreWhile overriding can the subclass choose not to throw an exception in java?
If the super-class method throws certain exception, you can override it without throwing any exception.ExampleIn the following example the sampleMethod() method of the super-class throws FileNotFoundException exception and, the sampleMethod() method does not throw any exception at all. Still this program gets compiled and executed without any errors.import java.io.File; import java.io.FileNotFoundException; import java.io.IOException; import java.util.Scanner; abstract class Super { public void sampleMethod()throws FileNotFoundException { System.out.println("Method of superclass"); } } public class ExceptionsExample extends Super { public void sampleMethod() { System.out.println("Method of Subclass"); } public static void main(String args[]) { ...
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