198: Mainline

When an instance method is called, the target argument's value is assigned to a special parameter, this. Thus, the this parameter's value is the target class instance. Accordingly, you can write, say, the Movie rating instance method in two ways. One way—the way introduced in Segment 194—exploits the convention that instance variables refer to the target instance:

public class Movie { 
 public int script, acting, direction; 
 public int rating () { 
  return script + acting + direction; 
 } 
} 

Another way to define rating uses the this parameter, thus referring to the target instance explicitly:

public class Movie { 
 public int script, acting, direction; 
 public int rating () { 
  return this.script + this.acting + this.direction; 
 } 
} 

Some programmers use this liberally, arguing that liberal use of this makes programs easier to understand. In this book, we use this only when necessary, believing that liberal use of this makes programs bulky.