In the last article we saw how to assigning values to variables and their respective ranges. Lets try to learn more on variables and strings. Use of variables is a key to efficient coding in any programming language. Variable declaration , if not done properly, can lead to many debugging errors.
Variable Assignment and Initialization
Once you have declared the type of a variable, you are free to initialize it and assign to it some value.
Assignment and initialization works just as they did in Perl. You simply use variable name = some value. For example, consider the following code:
marks = 66;
Of course you can also declare variables and assign values to them at the same time using the following syntax:
int marks = 66;
Casting (Changing from one type to another)
What if you want to multiply 3 x 1.5,Or say, int x double? Will the result be an int or a double or something else?
Well, when in doubt, Java will convert to the less restrictive type to be safe. Thus, in the above example, the result will be a double since double is less restrictive.
The following chart shows how types will be caste if possible.
byte --> short --> int --> long --> float --> double
However, what if you are going the other way? Suppose you have two doubles and you want to make an int out of the product
To do this type of caste, you simply perform an assignment using the type to be casted to in parentheses before the value to be casted. Consider the following example in which we caste from a double to an int:
double d = 345.456;
int i = (int) d;
In this case, it will be assigned a value of "345".
In Java, there is no variable type called string. However, although Java does not have a built-in String type, it does provide you will a predefined class called String which you can use instead.
I'll talk more about classes and using them in later articles. However, it would be nice to at least introduce the String class here so we can use it in the meantime.
To instantiate a String, you simply use the same syntax that you would if it were a type:
String s = "Hello Learner";
Strings have quite a few methods which allow you to manipulate them in every way that you could in Perl. To read about these methods, simply use the online documentation on java found on the SUN site.
In the later weeks, I will write in more about the intricacies that form an integral structure of the JAVA language. Currently I am doing a project with JAVA as the Front End and I learnt, the more you work in any programming language, the more you learn.
Next: Arrays and Overloading in Java