The name of the parent directory of the file or directory can be obtained using the method java.io.File.getParent(). This method returns the parent directory path name string or null if there is no parent named.A program that demonstrates this is given as follows −Example Live Demoimport java.io.File; public class Demo {    public static void main(String[] args) {       File file = new File("C:" + File.separator + "jdk11.0.2" + File.separator, "demo1.java");       System.out.println("File: " + file);       System.out.println("Parent: " + file.getParent());    } }The output of the above program is as follows −OutputFile: C:/jdk11.0.2/demo1.java Parent: ... Read More

The method java.io.File.isAbsolute() is used to check if the file object refers to an absolute pathname. This method returns true if the abstract path name is absolute and false if the abstract path name is not absolute.A program that demonstrates this is given as follows −Example Live Demoimport java.io.File; public class Demo {    public static void main(String[] args) {       File file = new File("C:" + File.separator + "jdk11.0.2" + File.separator, "demo1.java");       System.out.println(file.isAbsolute());    } }The output of the above program is as follows −OutputfalseNow let us understand the above program.The isAbsolute() method is used ... Read More

The name of the file and the name of the path can be obtained using the methods java.io.File.getName() and java.io.File.getPath() respectively. The getName() returns the name of the file or the directory. The getPath() returns the abstract pathname in the form of a pathname string.A program that demonstrates this is given as follows −Example Live Demoimport java.io.File; public class Demo {    public static void main(String[] args) {       File file = new File("C:" + File.separator + "jdk11.0.2" + File.separator, "demo1.java");       System.out.println("File name: " + file.getName());       System.out.println("Path name: " + file.getPath());    } ... Read More

The name can be validated using the java.util.regex.Pattern.matches() method. This method matches the regular expression for the name and the given input name and returns true if they match and false otherwise.A program that demonstrates this is given as follows:Example Live Demopublic class Demo {    public static void main(String args[]) {       String name = "John Harry Smith";       String regexName = "\p{Upper}(\p{Lower}+\s?)";       String patternName = "(" + regexName + "){2, 3}";       System.out.println("The name is: " + name);       System.out.println("Is the above name valid? " + name.matches(patternName));   ... Read More

The specified string can be split around a particular match for a regex using the String.split() method. This method has a single parameter i.e. regex and it returns the string array obtained by splitting the input string around a particular match for the regex.A program that demonstrates splitting a string is given as follows:Example Live Demopublic class Demo {    public static void main(String args[]) {       String regex = "_";       String strInput = "The_sky_is_blue";       System.out.println("Regex: " + regex);       System.out.println("Input string: " + strInput);       String[] strArr = ... Read More

The specified input sequence can be split around a particular match for a pattern using the java.util.regex.Pattern.split() method. This method has a single parameter i.e. the input sequence to split and it returns the string array obtained by splitting the input sequence around a particular match for a pattern.A program that demonstrates the method Pattern.split() in Java regular expressions is given as follows:Example Live Demoimport java.util.regex.Pattern; public class Demo {    public static void main(String[] args) {       String regex = "_";       String input = "Oranges_are_orange";       System.out.println("Regex: " + regex);       ... Read More

The Email address can be validated using the java.util.regex.Pattern.matches() method. This method matches the regular expression for the E-mail and the given input Email and returns true if they match and false otherwise.A program that demonstrates this is given as follows:Example Live Demopublic class Demo {    static boolean isValid(String email) {       String regex = "^[\w-_\.+]*[\w-_\.]\@([\w]+\.)+[\w]+[\w]$";       return email.matches(regex);    }    public static void main(String[] args) {       String email = "john123@gmail.com";       System.out.println("The E-mail ID is: " + email);       System.out.println("Is the above E-mail ID valid? " + ... Read More

The java.util.regex.Pattern.matches() method matches the regular expression and the given input. It has two parameters i.e. the regex and the input. It returns true if the regex and the input match and false otherwise.A program that demonstrates the method Pattern.matches() in Java regular expressions is given as follows:Example Live Demoimport java.util.regex.Pattern; public class Demo {    public static void main(String args[]) {       String regex = "a*b";       String input = "aaab";       System.out.println("Regex: " + regex);       System.out.println("Input: " + input);       boolean match = Pattern.matches(regex, input);       ... Read More

The Matcher can be reset using the java.util.regex.Matcher.reset() method. This method returns the reset Matcher.A program that demonstrates the method Matcher.reset() in Java regular expressions is given as follows:Example Live Demoimport java.util.regex.Matcher; import java.util.regex.Pattern; public class MainClass {    public static void main(String args[]) {       Pattern p = Pattern.compile("(a*b)");       Matcher m = p.matcher("caaabcccab");       System.out.println("The input string is: caaabcccab");       System.out.println("The Regex is: (a*b)");       System.out.println();       while (m.find()) {          System.out.println(m.group());       }       m.reset();       System.out.println("The ... Read More

The find() method finds the subsequence in an input sequence that matches the pattern required. This method is available in the Matcher class that is available in the java.util.regex package.A program that demonstrates the method Matcher.find() in Java regular expressions is given as follows:Example Live Demoimport java.util.regex.Matcher; import java.util.regex.Pattern; public class Demo {    public static void main(String args[]) {       Pattern p = Pattern.compile("Sun");       Matcher m = p.matcher("The Earth revolves around the Sun");       System.out.println("Subsequence: Sun");       System.out.println("Sequence: The Earth revolves around the Sun");       if (m.find())     ... Read More