Computer Science 1
Top Lectures Assignments Noticeboard

Using Classes, Part I

  1. Creating new object

    2. So far, we have used only predefined objects (like System.out), or constructed new String references by putting  string constants in double quotes ("").
    We need a general method for constructing new objects: So, to send a message to construct a new String reference, we would form it as String("hello world")
    Recall that a message must be sent to an object. The operator new arranges for an object to be created that can be sent the message: 
    new String ("hello world")
    This returns a reference to a newly created String object that. It is necessary to save a new reference if we want to use it later on Thus, reference variables become essential. 
    String s;
s = new String ("The british are coming");
    Using s we can continue to use this newly created object: 
    String upper, lower;
upper = s.toUpperCase ();
lower = s.toUpperCase ();
System.out.println (s);
Last modified: 1/18/99