How do I call a class from another class(not inheritance) in Java?

I think you're looking for the names of associations like aggregation and composition. The terms are used to describe Releationships in UML

Your question is not clear.

but maybe the following example will help:

class Scanner{
  public void scan(){}
}

//use inheritance
class SubScanner extends Scanner{
  public void scan(){}       //overriding
  public void scan(int i){}  //overloading
}

//use aggreagation
class MainClass{
  private final Scanner scanner;
  MainClass(Scanner scanner){
    this.scanner = scanner;
  }
  public void scan(){ 
    scanner.scan();         //delegation call
  }
}

If the scan method is an instance (object) method (not static), it would be something like this

Scanner s = new Scanner();
s.scan();

If scan is static (a class method), then

Scanner.scan();

Edit: The name of the relationship is Dependency in UML. You say that Main depends on Scanner or Main uses-a Scanner. I made this UML slideshow and cheatsheet:

http://www.loufranco.com/blog/files/UMLCheatsheet.html

If you have a Scanner member in the main class, then this is usually called has-a, composition, or an association.

Here is a table of many UML relationships

http://publib.boulder.ibm.com/infocenter/rtnlhelp/v6r0m0/index.jsp?topic=/com.ibm.xtools.modeler.doc/topics/rreltyp.html