Java Strings

Java Strings

A String stores text, like "Hello World". Strings are written in double quotes and are one of the most used types in Java.

Creating a string

String greeting = "Hello World";
System.out.println(greeting);

Useful string methods

String txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
System.out.println(txt.length()); // prints 26

String txt2 = "Please locate where 'locate' occurs!";
System.out.println(txt2.indexOf("locate")); // prints 7

• length() returns the number of characters.
• indexOf("text") returns the position of the first occurrence.

Changing case

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

Concatenation

Join strings with +:

String firstName = "John";
String lastName = "Doe";
System.out.println(firstName + " " + lastName);

Or use the concat() method:

String x = "Hello";
String y = "World";
System.out.println(x.concat(y));

String positions

String positions start at 0, so in "locate" inside the example, the l is at position 7.

TL;DR

• Strings hold text in double quotes.
• length() counts characters.
• + or concat() joins strings.
• toUpperCase() and toLowerCase() change case.