Java Series Part 4 – Strings & String Concatenation

Strings are used for storing text.

String variable contains a collection of characters surrounded by double quotes:

String greeting = "Hello";

A String in Java is actually an object, which contain methods that can perform certain operations on strings. For example, the length of a string can be found with the length() method:

System.out.println("The length of the txt string is: " + txt.length());

There are many string methods available, for example toUpperCase() and toLowerCase()

String txt = "Hello World";
System.out.println(txt.toUpperCase());   // Outputs "HELLO WORLD"
System.out.println(txt.toLowerCase());   // Outputs "hello world"

The indexOf() method returns the index (the position) of the first occurrence of a specified text in a string (including whitespace)

String txt = "Please locate where 'locate' occurs!";
System.out.println(txt.indexOf("locate")); // Outputs 7

String Concatenation


public class Ch5StringConcatenation {

public static void main(String[] args) {
    // TODO Auto-generated method stub

    String s1 = "1" + "2";
    System.out.println(s1); //prints 12

    String s2 = "1" + 2;
    System.out.println(s2); //prints 12

    String s3 = "1" + 2 + 3;
    System.out.println(s3); //prints 123

    String s4 = "ABC" + "DEF" + "GHI";
    System.out.println(s4); //prints ABCDEFGHI


Special Character in Strings

The sequence \"  inserts a double quote in a string

String txt = "We are the so-called \"Vikings\" from the north.";

The sequence \'  inserts a single quote in a string:

String txt = "It\'s alright.";

The sequence \\  inserts a single backslash in a string:

String txt = "The character \\ is called backslash.";

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