String / Reference / Processing.org

Class Name

String

Description

A string is a sequence of characters. The class String includes methods for examining individual characters, comparing strings, searching strings, extracting parts of strings, and for converting an entire string uppercase and lowercase. Strings are always defined inside double quotes ("Abc"), and characters are always defined inside single quotes ('A').

To compare the contents of two Strings, use the equals() method, as in if (a.equals(b)), instead of if (a == b). A String is an Object, so comparing them with the == operator only compares whether both Strings are stored in the same memory location. Using the equals() method will ensure that the actual contents are compared. (The troubleshooting reference has a longer explanation.)

Because a String is defined between double quotation marks, to include such marks within the String itself you must use the \ (backslash) character. (See the third example above.) This is known as an escape sequence. Other escape sequences include \t for the tab character and \n for new line. Because backslash is the escape character, to include a single backslash within a String, you must use two consecutive backslashes, as in: \\

There are more string methods than those linked from this page. Additional documentation is located online in the official Java documentation.

Examples

String str1 = "CCCP";
char data[] = {'C', 'C', 'C', 'P'};
String str2 = new String(data);
println(str1);  // Prints "CCCP" to the console
println(str2);  // Prints "CCCP" to the console

// Comparing String objects, see reference below.
String p = "potato";
// The correct way to compare two Strings
if (p.equals("potato")) {
  println("Yes, the values are the same.");
}

// Use a backslash to include quotes in a String
String quoted = "This one has \"quotes\"";
println(quoted);  // This one has "quotes"

Constructors

String(data)
String(data, offset, length)

Parameters

databyte[] or char[]: either an array of bytes to be decoded into characters, or an array of characters to be combined into a string
offsetint: index of the first character
lengthint: number of characters

Methods

toUpperCase()Converts all of the characters in the string to uppercase
toLowerCase()Converts all of the characters in the string to lowercase
substring()Returns a new string that is a part of the original string
length()Returns the total number of characters included in the String as an integer number
indexOf()Returns the index value of the first occurrence of a substring within the input string
equals()Compares two strings to see if they are the same
charAt()Returns the character at the specified index

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