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Articles by Maruthi Krishna
Page 46 of 50
Difference between the list() and listFiles() methods in Java
The class named File of the java.io package represents a file or directory (path names) in the system. To get the list of all the existing files in a directory this class provides the list() and ListFiles() methods.The main difference between them is thatThe list() method returns the names of all files in the given directory in the form of a String array.The ListFiles() method returns the objects (File) of the files in the given directory, in the form of an array of type File.i.e. If you just need the names of the files within a particular directory you can ...
Read MoreByte Streams in Java
These handle data in bytes (8 bits) i.e., the byte stream classes read/write data of 8 bits. Using these you can store characters, videos, audios, images etc.The InputStream and OutputStream classes (abstract) are the super classes of all the input/output stream classes: classes that are used to read/write a stream of bytes. Following are the byte array stream classes provided by Java −InputStreamOutputStreamFIleInputStreamFileOutputStreamByteArrayInputStreamByteArrayOutputStreamObjectInputStreamObjectOutputStreamPipedInputStreamPipedOutputStreamFilteredInputStreamFilteredOutputStreamBufferedInputStreamBufferedOutputStreamDataInputStreamDataOutputStreamExampleFollowing Java program reads data from a particular file using FileInputStream and writes it to another, using FileOutputStream.import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class IOStreamsExample { public static void main(String args[]) throws IOException { ...
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 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 MoreIlleagalStateException Vs NoSuchElementException in java?
When you call a method at illegal or inappropriate time an IlleagalStateException is generated.For example, the remove() method of the ArrayList class removes the last element after calling the next() or previous methods.After removing the element at the current position you need to move to the next element to remove it i.e. per one call of the next() method you can invoke this remove() method only once.Since the initial position of the list (pointer) will be before the first element, you cannot invoke this method without calling the next method.If you invoke the remove() method otherwise it throws an java.lang.IllegalStateException.Example: ...
Read MoreHow to write data to .csv file in Java?
A library named OpenCSV provides API’s to read and write data from/into a.CSV file. Here it is explained how to write the contents of a .csv file using a Java program.Maven dependency com.opencsv opencsv 4.4 org.apache.commons commons-lang3 3.9 The CSVWriter class of the com.opencsv package represents a simple csv writer. While instantiating this class you need to pass a Writer object representing the file, to which you want to write the data, as a parameter to its constructor.It provides methods named writeAll() and writeNext() to write data to a .csv file.Using the ...
Read MoreHow to read data from .csv file in Java?
A library named OpenCSV provides API’s to read and write data from/into a.CSV file. Here it is explained how to read the contents of a .csv file using a Java program.Maven dependency com.opencsv opencsv 4.4 org.apache.commons commons-lang3 3.9 The CSVReader class of the com.opencsv package represents a simple CSV reader. While instantiating this class you need to pass a Reader object representing the file to be read as a parameter to its constructor. It provides methods named readAll() and readNext() to read the contents of a .csv fileUsing the readNext() methodThe readNext() ...
Read MoreHow to read certain number of elements from a file in Java?
To read a fixed number of elements from a file you can either read a required number of data elements from the file and process them or, read the entire file into a collection or an array and process it for every n element.ExampleFollowing Java program, reads the contents of a file 10 words at a time and prints them in a separate line.import java.io.File; import java.io.FileNotFoundException; import java.util.Scanner; public class ReadingData { public static void main(String args[]) throws FileNotFoundException { //Creating an object of the File to read data File file = ...
Read MoreHow to read data from one file and print to another file in Java?
Java provides I/O Streams to read and write data where a Stream represents an input source or an output destination which could be a file, i/o devise, other programs, etc.In general, a Stream will be an input stream or, an output stream.InputStream − This is used to read data from a source.OutputStream − This is used to write data to a destination.Based on the data they handle there are two types of streams −Byte Streams − These handle data in bytes (8 bits) i.e., the byte stream classes read/write data of 8 bits. Using these you can store characters, videos, ...
Read MoreCan we use readUTF() to read a string from a .txt file in Java?
The readUTF() method of the java.io.DataOutputStream reads data that is in modified UTF-8 encoding, into a String and returns it.ExampleThe following Java program reads a UTF-8 text from a .txt file using the readUTF() method.import java.io.DataInputStream; import java.io.EOFException; import java.io.FileInputStream; import java.io.IOException; public class UTF8Example { public static void main(String args[]) { StringBuffer buffer = new StringBuffer(); try { //Instantiating the FileInputStream class FileInputStream fileIn = new FileInputStream("D:\test.txt"); //Instantiating the DataInputStream class DataInputStream inputStream = new DataInputStream(fileIn); ...
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