Java String Methods PDF

Java String  Java String String is a sequence of character treated as single unit such as “Hello World”. May include letters, digits, etc. String are immutable, once a string is created it cannot be changed. None of its methods changes the string.  Creating a String T...

Java String  Java String String is a sequence of character treated as single unit such as “Hello World”. May include letters, digits, etc. String are immutable, once a string is created it cannot be changed. None of its methods changes the string.  Creating a String The common way to create a string is by using string literals enclosed in double quotes and assgning them to a variable. Syntax: String variableName = “String”; String firstName = “Pedro”; String lastName = “Penduko”; String course = ”Computer Science”; String age = “22”;  String concatenation String firstName = “Pedro”; String lastName = “Penduko”; String course = ”Computer Science”; String BSCS = “Bachelor of science in “ + course String fullName = firstName + “ “ + lastName; String newString = firstName.concat(“ “).concat(lastName);  String Methods String methods in Java are built-in functions that make it easier to manipulate and work with strings. Commonly used String Method:.length().toLowerCase().charAt().concat().equals().replace().equalsIgnoreCase().trim().startWith().indexOf().endWith().toUpperCase()  String Methods The.length() method returns the length of the string. ex. String course = "Computer Science"; System.out.println(course.length()); //output: 16 The.charAt() method returns the character at the specified index. ex. String course = "Computer Science"; System.out.println(course.charAt(5)); //output: t  String Methods The.equals() method it compares the strings, it return true if arguments are the same sequence of character (case-sensitive) ex. String string1 = "Hello"; String string2 = "hello"; String string3 = "Hello"; System.out.println(string1.equals(string2)); //Output: false System.out.println(string1.equals(string3)); //Output: true  String Methods The.equalsIgnoreCase() method it compares the strings, it return true if arguments are the same sequence of character but ignoring case differences. ex. String string1 = "Hello"; String string2 = "hello"; String string3 = "Hello"; System.out.println(string1.equalsIgnoreCase(string2)); //Output: true  String Methods The.startsWith() method checks the string starts with the specified prefix. ex. String string1 = "Hello"; System.out.println(string1.startsWith(“He”)); //Output: true System.out.println(string1.startsWith(“he”)); //Output: false  String Methods The.endsWith() method checks the string ends with the specified prefix. ex. String string1 = "Hello"; System.out.println(string1.endsWith(“lo”)); //Output: true System.out.println(string1.endsWith(“llo”)); //Output: true System.out.println(string1.endsWith(“lO”)); //Output: false  String Methods The.toUpperCase() method converts all characters in a string to uppercase. ex. String string1 = "heLLo World!"; System.out.println(string1.toUpperCase()); //Output: HELLO WORLD!  String Methods The.toLowerCase() method converts all characters in a string to lowercase. ex. String string1 = "heLLo World!"; System.out.println(string1.toLowerCase()); //Output: hello world!  String Methods The.trim() method removes whitespace from the beginning and end. ex. String string1 = " hello world! "; System.out.println(string1.trim()); //Output: hello world!  String Methods The.indexOf() method searches for the first occurence of a character or substring. ex. String string1 = "hello world!”; System.out.println(string1.indexOf(“llo”)); //Output: 2 System.out.println(string1.indexOf(“abc”)); //Output: -1  String Methods The.concat() method combine the specified string to the end of the first string. ex. String string1 = "hello”; String string2 = “world” System.out.println(string1.concat(string2)); //Output: helloworld  String Methods The.concat() method combine the specified string to the end of the first string. ex. String string1 = "hello”; String string2 = “world” System.out.println(string1.concat(“kitty”)); //Output: hellokitty  String Methods The.concat() method combine the specified string to the end of the first string. ex. String string1 = "hello”; String string2 = “world” System.out.println(string1.concat(“kitty”)); //Output: hellokitty