Entering Non-Printable Characters

Problem

You need to put non-printable characters into strings.

Solution

Use the backslash character and one of the Java string escapes.

Discussion

The Java string escapes are listed in Table 3-1.

Table 3-1. String escapes

To get:

Use this:

Notes

Tab

 

Linefeed (Unix newline)

See System.getProperty("line.separator"), which gives you the platform’s line end.

Carriage return

 

Form feed

f

 

Backspace



 

Single quote

'

 

Double quote

"

 

Unicode character

u NNNN

Four hexadecimal digits (no x as in C/C++). See http://www.unicode.org for codes.

Octal(!) character

NNN

Who uses octal (base 8) these days?

Backslash

\

 

Here is a code example that shows most of these in action:

// StringEscapes.java
System.out.println("Java Strings in action:");
// System.out.println("An alarm or alert: a");    // not supported
System.out.println("An alarm entered in Octal: 07");
System.out.println("A tab key: 	(what comes after)");
System.out.println("A newline: 
(what comes after)");
System.out.println("A UniCode character: u0207");
System.out.println("A backslash character: \");

If you have a lot of non-ASCII characters to enter, you may wish to consider using Java’s input methods, discussed briefly in the JDK online documentation.

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