Java Articles - Page 390 of 440

Java lang package provides a Double class which has methods to convert Double to String and vice versa. You can convert a String to a double using the parseDouble() method and double to String using the toString() methodExampleLive Demopublic class StringDouble {    public static void main(String args[]){       Double data1 = 2.2;       String str = Double.toString(data1);       System.out.println(str);       Double data2 = Double.parseDouble(str);       System.out.println(data2);    } }Output2.2 2.2

Java String class provides several variants of valueOf() method. These accept various data types and convert them into String.ExampleLive Demopublic class Sample {    public static void main(String args[]){       int i = 200;       float f = 12.0f;       char c = 's';       char[] ch = {'h', 'e', 'l', 'l', 'o'};       String data = String.valueOf(i);       System.out.println(String.valueOf(i));       System.out.println(String.valueOf(f));       System.out.println(String.valueOf(c));       System.out.println(String.valueOf(ch));    } }Output200 12.0 s hello

You can change the cases using the toUpperCase() and toLowerCase() methods of the String class.ExampleLive Demopublic class Sample {    public static void main(String args[]){       String str = "Hello how are you";       String strUpper = str.toUpperCase();       System.out.println("Lower to upper : "+strUpper);       String strLower = str.toLowerCase();       System.out.println("Upper to lower : "+strLower);    } }OutputLower to upper : HELLO HOW ARE YOU Upper to lower : hello how are you

The split(String regex) method of the String class splits this string around matches of the given regular expression.ExampleLive Demopublic class Sample{    public static void main(String args[]){       String s = "|A|BB||CCC|||";       String[] words = s.split("\|");       for (String string : words) {          System.out.println(string);       }    } }OutputA BB CCC

A string is a collection of characters. In Java, it is represented by the String class, and it accepts NULL values. Checking for Null or Empty in Java In this article, we will learn if a string is null or empty in Java. The following are the ways to check if a string is null or empty in Java: Using isEmpty() Method Using length() Method Using isBlank() Method Using isEmpty() Method The isEmpty() method of the String class checks if a string is empty. It returns TRUE if ... Read More

We can verify whether the given string is empty using the isEmpty() method of the String class. This method returns true only if length() is 0.ExampleLive Demoimport java.lang.*; public class StringDemo {    public static void main(String[] args) {       String str = "tutorialspoint";       // prints length of string       System.out.println("length of string = " + str.length());       // checks if the string is empty or not       System.out.println("is this string empty? = " + str.isEmpty());    } }Outputlength of string = 14 is this string empty? = false

The toCharArray() method of a String class converts this string to a character array.ExampleLive Demoimport java.lang.*; public class StringDemo {    public static void main(String[] args) {       // converts String value to character array type value       String str = " Java was developed by James Gosling";       char retval[] = str.toCharArray();       // displays the converted value       System.out.println("Converted value to character array = ");       System.out.println(retval);    } }OutputConverted value to character array = Java was developed by James Gosling

Following are the important constructors of the StringTokenizer class.Sr.No.Constructor & Description1StringTokenizer(String str)This constructor a string tokenizer for the specified string.2StringTokenizer(String str, String delim)This constructor constructs string tokenizer for the specified string.3StringTokenizer(String str, String delim, boolean returnDelims)This constructor constructs a string tokenizer for the specified string.

To swap the contents of two strings (say s1 and s2) without the third, first of all concatenate them and store in s1. Now using the substring() method of the String class store the value of s1 in s2 and vice versa.Example Live Demopublic class Sample {    public static void main(String args[]){       String s1 = "tutorials";       String s2 = "point";       System.out.println("Value of s1 before swapping :"+s1);       System.out.println("Value of s2 before swapping :"+s2);       int i = s1.length();       s1 = s1+s2;       s2 = ... Read More

The StringTokenizer class of the java.util package allows an application to break a string into tokens.This class is a legacy class that is retained for compatibility reasons although its use is discouraged in new code.Its methods do not distinguish among identifiers, numbers, and quoted strings.This class methods do not even recognize and skip comments.ExampleLive Demoimport java.util.*;   public class Sample {    public static void main(String[] args) {         // creating string tokenizer       StringTokenizer st = new StringTokenizer("Come to learn");         // checking next token       System.out.println("Next token is : " + st.nextToken());   }     }OutputNext token is : Come