(Review:) How can you determine what an object of a particular class can do?
The variables and methods of a class will be documented somewhere.
String
With a Java development environment
such as such as Borland JBuilder or Symantec Café
the documentation is on-line
(in the editor, put the cursor over a class name and push F1).
If you got Java from Sun Microsystems, look
on your hard disk,
in someplace like
C:\jdk1.3\docs\index.html.
Here is a short version of the documentation for String.
// Constructors
public String();
public String(String value);
// Methods
public char charAt(int index);
public String concat(String str);
public boolean endsWith(String suffix);
public boolean equals(Object anObject);
public boolean equalsIgnoreCase(String anotherString);
public int indexOf(int ch);
public int indexOf(String str);
public int length();
public boolean startsWith(String prefix);
public String substring(int beginIndex, int endIndex);
public String toLowerCase();
public String toUpperCase();
public String trim();
The documentation first lists constructors. Then it describes the methods. For example,
public String concat(String str);
--+--- --+--- --+-- ----+----
| | | |
| | | |
| | | +---- says that there must be a
| | | String reference parameter
| | |
| | +----- the name of the method
| |
| +----- the method returns a reference
| to a new String object
|
+----- anywhere you have a String object,
you can use this method