Posts (page 179)
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5 min readIn Java, writing and reading files is a common task that can be accomplished using classes from the java.io package.To write to a file, you can create a FileWriter or BufferedWriter object and use its methods to write data to the file. You can also use PrintWriter or FileOutputStream classes for writing data to a file.To read from a file, you can use FileReader or BufferedReader classes to read the data from the file.
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5 min readThe Java String class is a built-in class that allows you to create and manipulate strings in Java. To use the String class, you can create a new String object using the new keyword, or simply assign a string literal to a String variable.Once you have a String object, you can use various methods provided by the String class to manipulate the string.
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6 min readIn Java, an interface is a reference type that can contain only abstract methods and constants. It is used to specify a set of methods that a class must implement. To work with interfaces in Java, you need to follow these steps:Define an interface by using the "interface" keyword followed by the name of the interface and a set of method signatures.Implement an interface in a class by using the "implements" keyword followed by the name of the interface.
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6 min readPolymorphism in Java can be implemented through method overriding and inheritance. Method overriding allows a subclass to provide a specific implementation of a method that is already defined in its superclass. This means that a method in a subclass can have the same name, return type, and parameters as a method in its superclass, but provide a different functionality.To implement polymorphism in Java, you can create a superclass with a method that is meant to be overridden by subclasses.
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7 min readTo sort an array in Java, you can use the Arrays.sort() method from the Java.util package. This method takes the array as input and sorts it in ascending order by default. You can also use the Collections.sort() method if you are working with a List instead of an array. If you need to sort the array in descending order, you can implement a custom Comparator and pass it as a second argument to the sort method.
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5 min readIn Java, an ArrayList is a class provided by the Java Collections Framework that is used to store and manipulate a dynamic collection of objects. To use an ArrayList in Java, you first need to import the necessary package using the import java.util.ArrayList; statement. Then, you can create an ArrayList object by specifying the data type of the objects it will store, like ArrayList<Integer> list = new ArrayList<Integer>();.
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6 min readTo read user input in Java, you can use the Scanner class which is found in the java.util package. First, you need to create an instance of the Scanner class by importing it at the top of your file:import java.util.Scanner;Then, create an object of the Scanner class and use its methods to read user input. You can use the next() method to read a single word, the nextLine() method to read an entire line of text, or methods such as nextInt(), nextDouble(), etc. to read specific types of data.
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5 min readWhen writing Java code, it is important to anticipate and handle exceptions that may occur during the execution of your program. Java provides a built-in exception handling mechanism that allows you to handle exceptions gracefully and prevent your program from crashing.To handle exceptions in Java, you can use the try-catch block. Inside the try block, you write the code that may throw an exception. If an exception occurs, it is caught by the corresponding catch block.
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5 min readIn Java, inheritance allows one class to inherit attributes and methods from another class. To implement inheritance in Java, you can use the extends keyword to indicate that a class is a subclass of another class.When creating a new class that wants to inherit from an existing class, you simply write public class NewClass extends ExistingClass { }. This means that NewClass is inheriting from ExistingClass and will have access to all its public and protected attributes and methods.
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3 min readTo loop through an array in Java, you can use a for loop or an enhanced for loop (also known as a for-each loop).With a for loop, you would specify the length of the array as the condition for the loop and iterate through each element by using the index variable to access each element.Example: int[] numbers = {1, 2, 3, 4, 5}; for(int i = 0; i < numbers.length; i++) { System.out.
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7 min readIf-else statements in Java are used to make decisions in the program based on a condition.
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5 min readIn Java, a constructor is a special method that is used to initialize objects of a class. It has the same name as the class and does not have a return type. It is commonly used to set initial values for instance variables or perform any necessary setup tasks when an object is created.To write a constructor in Java, you simply define a method with the same name as the class and include any required parameters inside the parentheses.