Strings

Strings are enclosed in double quotes ("), whereas characters are enclosed in single quotes (').

11 Common operations

The associated type is String. You can perform assignments and concatenations (= and +); new is optional in the declaration.

• The length of a string is returned by chaine.length(), with parentheses, unlike arrays.
• Equality is tested with equals (or equalsIgnoreCase if you do not care about case).
• The n-th character is obtained with charAt.

String maChaine = "Hello dear students!";
for (int i = 0; i < maChaine.length(); i++) {
    System.out.println(maChaine.charAt(i));
}

== compares references, equals compares contents

public class Demo {
    public static void main(String[] args) {
        String a = "java";
        String b = "java";
        String c = new String("java");

        System.out.println("a == b       : " + (a == b));       // true: same cached object
        System.out.println("a == c       : " + (a == c));       // false: two different objects
        System.out.println("a.equals(c)  : " + a.equals(c));    // true: same contents
        System.out.println("equalsIgnoreCase : " + a.equalsIgnoreCase("JAVA"));

        System.out.println("length       : " + a.length());
        System.out.println("3rd character: " + a.charAt(2));
        System.out.println("upper case   : " + a.toUpperCase());
        System.out.println("concatenation : " + a + " " + 8);
    }
}