The java.lang package is automatically loaded by the Java compiler,so you do not have to import it to use the classes in this packge.

Java's primitive data types

Java is not just a language that supports object oriented programming. Java is an object oriented programming language. Java only has a small number of primitive data types.

Primitive data types

Example

public class MyChar {
    public static void main(String args[]){
		char c1 = 'A';
		char c2 = 'z';
		char c3 = '5';

		Character objectChar = new Character('O');

		System.out.println("Is character "+ c1 + "uppercase? " +
		  Character.isUppercase(c1));
		System.out.println("Is character "+ c2 + "uppercase? " +
		  Character.isUppercase(c2));
		System.out.println("Is character "+ c3 + "a digit? " +
		  Character.isDigit(c3));
		System.out.println("Convert "+ c1 + "to lowercase: " +
		  Character.toLowerCase(c1));

		System.out.println("Character object objectChar is: " +
		          objectChar.charValue());

	}
}


               This program produces the following output:
               $ java MyChar
               Is character A uppercase? true
               Is character z uppercase? false
               Is character 5 a digit? true
               Convert A to lowercase: a
               Character object objectChar is: O
					
Example of using Integer class with parseInt method
to convert a string into an integer:

public class MyApplet extends Applet {
    public void init() {
        String number = getParameter("numberOfImages");
        int nImages = 0;
        try {
            nImages = Integer.parseInt(number);
        } catch(Exception e) {
            System.out.println(
              "MyApplet.init: exception: numberOfImages parameter is " +
              numberOfImages + " - expected integer.");
        }
        // ... do smth ...
    }
    // .. more methods
}          

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