Java Controlling Case - Web Development and Design | Tutorial for Java, PHP, HTML, Javascript Java Controlling Case - Web Development and Design | Tutorial for Java, PHP, HTML, Javascript

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Thursday, December 27, 2018

Java Controlling Case

Java Controlling Case

Problem 

You need to convert strings to uppercase or lowercase, or to compare strings without regard for case. 

Solution 

The String class has a number of methods for dealing with documents in a particular case. toUpperCase( ) and toLowerCase( ) each return a new string that is a copy of the current string, but converted as the name implies. Each can be called either with no arguments or with a Locale argument specifying the conversion rules; this is necessary because of internationalization.

Java provides significantly more internationalization and localization features than ordinary languages, a feature that is covered in Chapter 15. While the equals( ) method tells you if another string is exactly the same, equalsIgnoreCase( ) tells you if all characters are the same regardless of case. Here, you can’t specify an alternate locale; the system’s default locale is used:

// Case.java
String name = "Java Cookbook";
System.out.println("Normal:\t" + name);
System.out.println("Upper:\t" + name.toUpperCase( ));
System.out.println("Lower:\t" + name.toLowerCase( ));
String javaName = "java cookBook"; // As if it were Java identifiers :-)
if (!name.equals(javaName))
 System.err.println("equals( ) correctly reports false");
else
 System.err.println("equals( ) incorrectly reports true");
if (name.equalsIgnoreCase(javaName))
 System.err.println("equalsIgnoreCase( ) correctly reports true");
else
 System.err.println("equalsIgnoreCase( ) incorrectly reports false");

If you run this, it prints the first name changed to uppercase and lowercase, then it reports that both methods work as expected.

C:\javasrc\strings>java Case
Normal: Java Cookbook
Upper: JAVA COOKBOOK
Lower: java cookbook
equals( ) correctly reports false
equalsIgnoreCase( ) correctly reports true

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