public
class StaticDemo
...{
public String my_member_variable =
"somedata";
public
static
void main (String args[])
...{
// Access a non-static member from static method
System.out.println ("This generates a compiler error"
+
my_member_variable );
}
}
如果你要访问一个静态方法中的成员变量(比如main方法),你就需要实例化一个对象。下面这段代码示例了如何正确的访问一个非静态的成员变量,其方法就是首先实例化一个对象。
public
class NonStaticDemo
...{
public String my_member_variable =
"somedata";
public
static
void main (String args[])
...{
NonStaticDemo demo =
new NonStaticDemo();
// Access member variable of demo
System.out.println ("This WON'T generate an error"
+
demo.my_member_variable );
}
}
// Create an array of three strings
String[] strArray =
new String[3];
// First element's index is actually 0
strArray[0] =
"First string";
// Second element's index is actually 1
strArray[1] =
"Second string";
// Final element's index is actually 2
strArray[2] =
"Third and final string";
import java.util.Date;
import java.util.Calendar;
public
class ZeroIndexedDate
...{
public
static
void main (String args[])
...{
// Get today's date
Date today =
new Date();
// Print return value of getMonth
System.out.println ("Date.getMonth() returns : "
+
today.getMonth());
// Get today's date using a Calendar
Calendar rightNow = Calendar.getInstance();
// Print return value of get ( Calendar.MONTH )
System.out.println ("Calendar.get (month) returns : "
+
rightNow.get ( Calendar.MONTH ));
}
}
public
static
void main(String args[])
...{
// Accept up to 3 parameters
String[] list =
new String[3];
int index =
0;
while ( (index < args.length) && ( index <
3 ) )
...{
list[index++] = args[index];
}
// Check all the parameters
for (int i =
0; i < list.length; i++)
...{
if (list.equals "-help")
...{
// ……
}
else
if (list.equals "-cp")
...{
// ……
}
// else ……
}
}