(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
(push F1).
If you downloaded the JDK 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
.
There are more methods than in this list.
// 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