http://java.sun.com/docs/books/tutorial/java/index.html

http://java.sun.com/products/jdk/1.1/docs/api/packages.html

package games.poker; // always the first declaration in a file

import java.util; // can access util.Hashtable

import java.util.Hashtable; // can access Hashtable

import java.util.*; // can access all classes within util

import java.lang.*;

class Circle
{
  static final double PI = 3.14159;
  double x, y; // the center of the circle
  double radius;
  Circle(double nx, double ny, double nr) {x=nx; y=ny; r=nr;}
  Circle(double nr) {this(0.0; 0.0, nr);}
  double area() { return PI * radius * radius; }
  double circumference() { return 2 * PI * radius; }
  static double nTimesPI(int n) {return n * PI;}
}

class Circle
{
  static final double PI = 3.14159;
  double x, y; 
  double radius;
  ...
}

class Circle
{

...
double area() { return PI * radius * radius; }
double circumference() { return nTimesPI(2) * radius; }
static double nTimesPI(int n) {return n * PI;}

}

class Circle
{

...
Circle(double nx, double ny, double nr) {x=nx; y=ny; r=nr;}
Circle(double nr) {this(0.0, 0.0, nr);}
...

}

Circle c2 = new Circle(1.0, 2.0, 3.0);  // calls first constructor
Circle c1 = new Circle(1.9); // calls second constructor

double aSum = c1.area() + c2.area();
double rSum = c1.radius + c2.radius;

double fourPI = c1.nTimesPI(2) + Circle.nTimesPI(2);

Button a = new Button("On");
Button b = new Button("Off");
a = b; // now both a and b refer to object labelled Off
int x = 1;
int y = 2;
x = y; // now x and y both have the value 2, but they have distinct storage

if ( v1.equals(v2) ) // they are equal!

char s[] = new char[100];
char[] s1 = new char[50]; // brackets may go either place in declaration

for (int i=0; i<s.length; i++)

... s[i] ...

int i = -1, j = 100;
char c = s[i] + s[j] ; // either will throw IndexOutOfBoundsException

Circle[] ca = new Circle[100]; // elements are all null

Circle[] ca1 = {new Circle(1.0), new Circle(2.0), new Circle(3.0)};
char[] s2 = {'a', 'b', 'c'};

Button buttons[] = new Button[10]; // array of 10 null pointers
for (int i=0; i<buttons.length; i++)
  buttons[i] = new Button("label " + i); // must allocate elements

String s = "Hello there";

char[] a = {'H','e','l','l','o',' ','t','h','e','r','e'};
String s = new String(a);

String s2 = s + " everyone";
s2 += " here";
s2 = s2.concat(" and now");

StringBuffer b = new StringBuffer("Hello");
b.append(" there");
b.setCharAt(0, 'M');
b.setLength(b.length()-3); // chops off last three characters
String s = b.toString(); // converts b to a String

StringBuffer b1(100); // initial value is ""
b1.capacity() // returns 100
StringBuffers are reallocated if more space is necessary

class Outer
{
  int x;
  class Inner
  {
    int y;
    // can reference x
  }
}

class Outer
{
  int x;
  static class ListNode
  {
    int info;
    ListNode next;
    ListNode(int newInfo, ListNode newNext)
    {
      info = newInfo;
      next = newNext;
      // can't reference x
    }
  }
}

class ListNode
{
  int info;
  ListNode next;
  static int length(ListNode l)
  {
    return l == null ? 0 : 1 + length(l.next);
  }
}

while ( p != null )  ...
if ( i != 0 ) ...

int i, j;
for (i=0, j=1; i*j < 100; i++, j--) ...
int a[] = {0,1,2,3,4,5,6,7,8,9};

for (int k=0; k < a.length; k++)
  System.out.println("a[" + k + "] = " + a[k]);

outer:for (...)
  for (...)
    break outer;