Java provides the java.util.regex package for pattern matching with regular expressions. You can then search for a pattern in a Java string using classes and methods of this packages.Exampleimport java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexMatches {    public static void main( String args[] ) {       String line = "This order was placed for QT3000! OK?";       String pattern = "(.*)(\d+)(.*)";       Pattern r = Pattern.compile(pattern);       Matcher m = r.matcher(line);             if (m.find( )) {          System.out.println("Found value: " + m.group(0));     ... Read More

To count the number of lines in a file Instantiate the FileInputStream class by passing an object of the required file as parameter to its constructor. Read the contents of the file to a byte array using the read() method of FileInputStream class. Instantiate a String class by passing the byte array obtained, as a parameter its constructor. Finally, find the length of the string. Example import java.io.File; import java.io.FileInputStream; public class NumberOfCharacters { public static void main(String args[]) throws Exception{ File file = new File("data"); FileInputStream ... Read More

"On a mean, a developer spends a considerable quantity of your time doing mundane tasks compiling the code, packaging the binaries, deploying the binaries to the checkserver, testing the changes," copying the code from one location to another. To automate and simplify these tasks we can use build tools like Ant, Maven, Gradle etc.

To count the number of lines in a fileInstantiate the FileInputStream class by passing an object of the required file as parameter to its constructor.Read the contents of the file to a bytearray using the read() method of FileInputStream class.Instantiate a String class by passing the byte array obtained, as a parameter its constructor.Now, split the above string into an array of strings using the split() method by passing the regular expression of the new line as a parameter to this method.Now, find the length of the obtained array.Exampleimport java.io.File; import java.io.FileInputStream; public class NumberOfCharacters {    public static void main(String args[]) throws Exception{ ... Read More

Read the number of words in text fileCreate a FileInputStream object by passing the required file (object) as a parameter to its constructor.Read the contents of the file using the read() method into a byte array. Insatiate a String class by passing the byte array to its constructor.Using split() method read the words of the String to an array.Create an integer variable, initialize it with 0, int the for loop for each element of the string array increment the count.Exampleimport java.io.File; import java.io.FileInputStream; public class Sample {    public static void main(String args[]) throws Exception{       int count =0;       File ... Read More

Declare an integer, initialize it with 0, in for loop increment it for each character.ExampleLive Demopublic class Sample {    public static void main(String args[]) {       String str = new String("Hi welcome to Tutorialspoint");       int count = 0;       for(int i = 0; i

To convert the contents of an ArrayList to a String, create a StringBuffer object append the contents of the ArrayList to it, finally convert the StringBuffer object to String using the toString() method. Example import java.util.ArrayList; public class String_ArrayList { public static void main(String args[]) { ArrayList al = new ArrayList(); al.add("Hello"); al.add("are"); al.add("you"); StringBuffer sb = new StringBuffer(); for (String s : al) { sb.append(s); sb.append(" "); } String str = sb.toString(); System.out.println(str); } } Output Hello are you

You can convert an array of Strings to a single array using the collect() method.ExampleLive Demoimport java.util.Arrays; import java.util.stream.Collectors; public class CreatngStringFromArray {    public static void main(String args[]) {       String [] myArray = {"Welcome", "to", "Tutorialspoint"};       String str = Arrays.stream(myArray).collect(Collectors.joining(" "));       System.out.println(str);    } }OutputWelcome to Tutorialspoint

You can extract a substring from a String using the substring() method of the String class to this method you need to pass the start and end indexes of the required substring.ExampleLive Demopublic class Substring {    public static void main(String args[]) {       String str = "Welcome to Tutorialspoint";       String sub = str.substring(10, 25);       System.out.println(sub);    } }OutputTutorialspoint

To extract last n characters, simply print (length-n)th character to nth character using the charAt() method.ExampleLive Demopublic class ExtractingCharactersFromStrings {    public static void main(String args[]) {           String str = "Hi welcome to tutorialspoint";       int n = 5;       int initial = str.length()-5;       for(int i=initial; i