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Java String
String is a collection of characters. In Java, strings are class object. A Java string is not a character array and is not terminated by NULL character.
Syntax: In Java, String is declared as follows:
String s = new String("Java Programming"); or String s; s = new String("Java Programming"); or String s = "Java Programming";
Example 1: Input string name and display with hello.
public static void main(String[] args) { String s; Scanner scan = new Scanner(System.in); System.out.println("Enter Name: "); s = scan.nextLine(); System.out.println("Hello, " + s); }
Java String methods
The String class defines a number of methods that allow us to manipulate a string.
Example: toLowerCase()
public static void main(String[] args) { String s1; Scanner in = new Scanner(System.in); System.out.println("Enter string"); s1 = in.nextLine(); s1=s1.toLowerCase(); System.out.println("S1 = " + s1); }
Example: toUpperCase()
public static void main(String[] args) { String s1; Scanner in = new Scanner(System.in); System.out.println("Enter string"); s1 = in.nextLine(); s1=s1.toUpperCase(); System.out.println("S1 = " + s1); }
Example: concat()
public static void main(String[] args) { String s1, s2, s3; Scanner in = new Scanner(System.in); System.out.println("Enter 2 string"); s1 = in.nextLine(); s2 = in.nextLine(); s3 = s1 + s2; System.out.println("After concat new string is : " + s3); }
Example: replace()
public static void main(String[] args) { String s1; Scanner in = new Scanner(System.in); System.out.println("Enter string"); s1 = in.nextLine(); //s1=s1.replace('a', 'b'); //s1=s1.replace("java", "cpp"); s1=s1.replaceFirst("java", "cpp"); System.out.println("S1 = " + s1); }
Example: trim()
Example: equals()
public static void main(String[] args) { String s1, s2; Scanner in = new Scanner(System.in); System.out.println("Enter 1st string"); s1 = in.nextLine(); System.out.println("Enter 2nd string"); s2 = in.nextLine(); //boolean a = s1.equals(s2); boolean a = s1.equalsIgnoreCase(s2); if(a) System.out.println("Strings are equal"); else System.out.println("Strings are not equal"); }
Example: compareTo()
public static void main(String[] args) { String s1, s2; Scanner in = new Scanner(System.in); System.out.println("Enter 1st string"); s1 = in.nextLine(); System.out.println("Enter 2nd string"); s2 = in.nextLine(); int i = s1.compareTo(s2); //int i = s1.compareToIgnoreCase(s2); if(i==0) System.out.println("Strings are equal"); else if(i<0) System.out.println("2nd Strings is greater"); else System.out.println("1st Strings is greater"); }
Example: substring()
public static void main(String[] args) { String s1, s2; Scanner in = new Scanner(System.in); System.out.println("Enter string: "); s1 = in.nextLine(); //s2 = s1.substring(3); s2 = s1.substring(3,5); System.out.println("After substring, new string is = " + s2); }
Example: charAt()
public static void main(String[] args) { String s1, s2; Scanner in = new Scanner(System.in); System.out.println("Enter string"); s1 = in.nextLine(); char ch = s1.charAt(5); System.out.println("character at 5th position = " + ch); }
In Java, strings are class objects and implemented using two classes, i.e. String and StringBuffer.