More about Objects and Classes
The relational operations on primitive data are ==, >=, <=, >, <, and !=. They compare two data values, when those values' type has an ordering. For example, integers are ordered by size or magnitude. The result of a relational operation is a boolean value: either True or False. The relational operators on objects like Strings are different, and they are expressed as methods. Pay special attention to the equality method, equals().
7. The toString() Method
Answer:Yes, even though the phrase is a little bit deceptive. One should really say
"the object currently referenced by
a," or "the object referred to by
a," or "the object
but usually people say "the object
a" and expect you to know what they mean.
The example program does very little that is visible on the monitor screen. It would be nice to print something out. The bytes that make up an object cannot be sent directly to the monitor because they are not ASCII character data. For example,
ints of a
Point use a data type that can't be sent directly to a monitor. Of course, the methods of an object are in Java bytecode, which makes no sense to a monitor, either.
Luckily, there is a method defined in class
Point that can be used to create a printable
String for a
Point object. Point, class
toString() method of a
Point object creates a
String object, which can then be printed. Look at the documentation:
public String toString(); // returns character data that can be printed | | | | | +--- this is the method name. It takes no parameters. | | | +--- this says that the method returns a String object | +--- anywhere you have a Point object, you can use this method
All objects have their own
toString()method, so it is possible to print out something for any object your program has created. (Often, though, the
Stringis not very useful.)
(Review: ) What is a parameter?