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Articles by Maruthi Krishna
Page 41 of 50
How 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.Example Live Demointerface 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 MoreIs parent child hierarchy important on throws while overriding in Java?
When you try to handle an exception (checked) thrown by a particular method, you need to catch it using the Exception class or super class of the Exception occurred.In the same way while overriding the method of a super class, if it throws an exception −The method in the sub-class should throw the same exception or its sub type.The method in the sub-class should not throw its super type.You can override it without throwing any exception.When you have three classes named Demo, SuperTest and, Super in (hierarchical) inheritance, if Demo and SuperTest have a method named sample().Example Live Democlass Demo { ...
Read MoreProgram to replace all the characters in of a file with '#' except a particular word in Java
The split() method of the String class. splits the current string around matches of the given regular expression. The array returned by this method contains each substring of this string that is terminated by another substring that matches the given expression or is terminated by the end of the string.The replaceAll() method of the String class accepts two strings representing a regular expression and a replacement String and replaces the matched values with given String.To replace all the characters in of a file with '#' except a particular word (one way) −Read the contents of a file to a String.Create ...
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 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.Example Live Demoimport 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 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. Live Demopublic 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 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.Example Live Demoimport 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 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 do we mix two strings and generate another in java?
Strings are used to store a sequence of characters in Java, they are treated as objects. The String class of the java.lang package represents a String.You can create a String either by using the new keyword (like any other object) or, by assigning value to the literal (like any other primitive datatype).String stringObject = new String("Hello how are you"); String stringLiteral = "Welcome to Tutorialspoint";Concatenating StringsYou can concatenate Strings in Java in the following ways −Using the "+" operator − Java Provides a concatenation operator using this, you can directly add two String literalsExampleimport java.util.Scanner; public class StringExample { ...
Read MoreIn how many ways we can convert a String to a character array using Java?
You can convert a String to a character array either by copying each element of the String to an array or, using the toCharArray() method.Copying each elementGet the String to be converted.Create an empty character array with the length of the String.The charAt() method of the String class returns the character at a particular position. Using this method copy each character of the String to the array.Example Live Demoimport java.util.Arrays; import java.util.Scanner; public class StringToCharArray { public static void main(String args[]) { Scanner sc = new Scanner(System.in); System.out.println("Enter a String value: "); ...
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