Introduction In this article, we'll explore how to check whether a given string contains only digits or a mix of digits and other characters in Java. We'll achieve this by using the String class and its matches() method. Problem Statement Given a string write a Java program to check whether it contains only digit characters. Input 1 4434 Output 1 String contains only digits! Input 2 5demo9 Output 2 String contains digits as well as other characters! Steps to check digit characters in String The following are the steps to check whether the String contains only digit characters in ... Read More

To delete all whitespaces from a string, use the replaceAll() method and replace every whitespace with empty.Let’s say the following is our string.String str = "This is it!";Now, let us replace the whitespaces that will eventually delete them.String res = str.replaceAll("\s+","");Example Live Demopublic class Demo {    public static void main(String []args) {       String str = "This is it!";       System.out.println("String: "+str);       String res = str.replaceAll("\s+","");       System.out.println("String after deleting whitespace: "+res);    } }OutputString: This is it! String after deleting whitespace: Thisisit!

To swap the case of a string, use.toLowerCase() for title case string. toLowerCase() for uppercase stringtoUpperCase() for lowercase stringLoop through what we discussed above for all the characters in the sting.for (int i = 0; i > len; i++) {    c = str.charAt(i);    // title case converted to lower case    if (Character.isTitleCase(c)) {       c = Character.toLowerCase(c);    }    // upper case converted to lower case    if (Character.isUpperCase(c)) {       c = Character.toLowerCase(c);    }    // lower case converted to upper case    if (Character.isLowerCase(c)) {       c ... Read More

To construct on string from another, firstly take a charcter array for the first string.char ch[] = { 'A', 'M', 'I', 'T' }; String str1 = new String(ch);The above forms first string. Now, let us created another string from the first string.String str2 = new String(str1);In this way, we can easily construct one string from another.Example Live Demopublic class Demo {    public static void main(String[] args) {       char ch[] = { 'A', 'M', 'I', 'T' };       String str1 = new String(ch);       String str2 = new String(str1);       String str3 ... Read More

To extract a substring as an array of characters in Java, use the getChars() method.Let’s say the following is our string and character array.String str = "World is not enough!"; char[] chArr = new char[10];Now, use the getChars() method to extract a substring.str.getChars(13, 19, chArr, 0);The above substring is an array of characters which can be displayed as shown in the complete example below −Example Live Demopublic class Demo {    public static void main(String[] args) {       String str = "World is not enough!";       char[] chArr = new char[10];       str.getChars(13, 19, chArr, ... Read More

To get a string from a subset of the character array elements, use the copyValueOf() method. This method returns a String that represents the character sequence in the array specified.Here is our character array.char[] ch = { 'T', 'E', 'S', 'T', 'I', 'N', 'G'};Now, let us create a string from the subset of the above array elements.String str = String.copyValueOf(ch, 4, 2);Example Live Demopublic class Demo {    public static void main(String[] args) {       char[] ch = { 'T', 'E', 'S', 'T', 'I', 'N', 'G'};       String str = String.copyValueOf(ch, 4, 2);       System.out.println(str);    } }OutputIN

Here is our character array.char[] ch = { 'T', 'E', 'S', 'T', 'I', 'N', 'G'};Create string object from some part of a string using the following String constructor. Through this we are fetching substring “IN” from the character array.String str = new String(ch, 4, 2);Example Live Demopublic class Demo {    public static void main(String[] args) {       char[] ch = { 'T', 'E', 'S', 'T', 'I', 'N', 'G'};       String str = new String(ch, 4, 2);       System.out.println(str);    } }OutputIN

Here is our character array.char[] ch = { 'T', 'E', 'S', 'T'};To create string object from the above character array is quite easy. Add the array to the string parameter as shown below −String str = new String(ch);Example Live Demopublic class Demo {    public static void main(String[] args) {       char[] ch = { 'T', 'E', 'S', 'T'};       String str = new String(ch);       System.out.println(str);    } }OutputTEST

Argument indices allow programmers to reorder the output. Let us see an example.Example Live Demopublic class Demo {    public static void main(String[] args) {       System.out.printf("Before reordering = %s %s %s %s %s %s", "one", "two", "three", "four", "five", "six" );       System.out.printf("After reordering = %6$s %5$s %4$s %3$s %2$s %1$s", "one", "two", "three", "four", "five", "six" );       System.out.printf("Before reordering = %d %d %d", 100, 200, 300);       System.out.printf("After reordering = %2$d %3$d %1$d", 100, 200, 300);    } }OutputBefore reordering = one two three four five six After reordering = ... Read More

To display localized method name in Java, use the ‘B’ conversion character.System.out.printf("Localized month : %TB", d);To display method name in lowercase, use the “%tb”System.out.printf("Localized month : %tB", d);Example Live Demoimport java.util.Date; public class Demo {    public static void main(String[] args) {       Date d = new Date();       System.out.printf("Morning/afternoon indicator: %tp", d);       System.out.printf("Morning/afternoon indicator: %Tp", d);       System.out.printf("Localized month : %tB", d);       System.out.printf("Localized month : %TB", d);    } }OutputMorning/afternoon indicator: pm Morning/afternoon indicator: PM Localized month : November Localized month : NOVEMBERRight justify and left justify values ... Read More