Parameters Must be the Correct Type

When a method starts running, it must have the right number of parameters, and each parameter must be of the required type. However, sometimes, just before a method starts running, the values supplied in a parameter list are converted to the required type. There are two ways in which this can happen:

1. Explicitly---the programmer asks for values to be converted with a type cast.
2. Implicitly---if the compiler can make the conversion without loss of information, or with only a small loss of precision, it will automatically do so.

A type cast looks like this:

(requiredType)(expression)

The (requiredType) is something like (int). The (expression) is an ordinary expression. If it is a single variable, you don't need the surrounding parentheses. Here is an example program that shows a type cast:

import java.awt.*;      // import the class library where Point is defined
class typeCastEg
{

  public static void main ( String arg[] )
  {
    Point pointB = new Point();     // create a point at x=0 y=0
    pointB.move( (int)14.305, (int)(34.9-12.6) );
    System.out.println("New location:" + pointB );
  }
}

In this case, a type cast is required for both parameters because converting a floating-point number to an int will usually lose information. In casting a floating-point value to an int, the fractional part will be lost. (Not rounded.)