4-1ע͵HelloJava
/**
 * Javadocעͷ һHello Java!ĳ
 * <p>
 * ԴӡHello Java!
 * 
 * @author 
 * @version 1.0.1, 2008-01-25
 * 
 */

public class HelloJava {
	/*
	 * עͷ main()ǳִе
	 */
	public static void main(String[] args) {
		// עͷ
		// дӡHello Java!
		System.out.println("Hello Java!");
	}
}


4-2
public class Variable {
	 public static void main(String[] args) {
		int n;// n
		n = 1;// nֵֵΪ1
		System.out.println(n); // ǰnֵ
		n = 2;// nֵֵΪ2""
		System.out.println(n); // ǰnֵ
	}
}


4-3
public class Variable1 {
	 public static void main(String[] args) {
		int n = 1;// nnֵֵΪ1
		System.out.println(n);// ǰnֵ
		n = 2;// nֵֵΪ2""
		System.out.println(n);
	}
}


4-4
public class TypeConvert {
	public static void main(String args[]) {
		int i = (int) 18.9;
		byte b = (byte) 150;
		float f = 100;
		System.out.println("i=" + i);
		System.out.println("b=" + b);
		System.out.println("f=" + f);
	}
}


 4-5
public class Conversion {
	public static void main(String args[]) {
		byte b;
		int i = 257;
		double d = 323.142;

		System.out.println("\nConversion of int to byte.");
		b = (byte) i;
		System.out.println("i and b " + i + " " + b);

		System.out.println("\nConversion of double to int.");
		i = (int) d;
		System.out.println("d and i " + d + " " + i);

		System.out.println("\nConversion of double to byte.");
		b = (byte) d;
		System.out.println("d and b " + d + " " + b);
	}
}


4-6
public class StringToInt {
	public static void main(String args[]) {
		int i;
		String s = "126";
		i = Integer.parseInt(s);
		System.out.println(i);
	}
}


4-7
public class MultByTwo {
	public static void main(String args[]) {
		int i;
		int num = 0xFFFFFFE;
		num = num << 1;
		System.out.println(num);
		num = num << 1;
		System.out.println(num);
	}
}


4-8   ǼһָеӢ
class Light {
	int lightspeed;
	long days;
	long seconds;
	long distance;

	Light(int a, long b) {
		lightspeed = a;
		days = b;
	}

	public long getDistance() {
		distance = lightspeed * seconds;
		return distance;
	}

	public long getSeconds() {
		seconds = days * 24 * 60 * 60;
		return seconds;
	}

	public static void main(String args[]) {

		Light light = new Light(186000, 1000);
		System.out.print("In " + light.getSeconds());
		System.out.print(" days light will travel about ");
		System.out.println(light.getDistance() + " miles.");
	}
}

4-9
class BasicMath {
	public static void main(String args[]) {
		System.out.println("Integer Arithmetic");
		int a = 1 + 1;
		int b = a * 3;
		int c = b / 4;
		int d = c - a;
		int e = -d;
		System.out.println("a = " + a);
		System.out.println("b = " + b);
		System.out.println("c = " + c);
		System.out.println("d = " + d);
		System.out.println("e = " + e);
		System.out.println("\nFloating Point Arithmetic");
		double da = 1 + 1;
		double db = da * 3;
		double dc = db / 4;
		double dd = dc - a;
		double de = -dd;
		System.out.println("da = " + da);
		System.out.println("db = " + db);
		System.out.println("dc = " + dc);
		System.out.println("dd = " + dd);
		System.out.println("de = " + de);
	}
}

4-10
class OpEquals {
	public static void main(String args[]) {
		int a = 1;
		int b = 2;
		int c = 3;
		a += 5;
		b *= 4;
		c += a * b;
		c %= 6;
		System.out.println("a = " + a);
		System.out.println("b = " + b);
		System.out.println("c = " + c);
	}
}

4-11
class IncDec {
	public static void main(String args[]) {
		int a = 1;
		int b = 2;
		int c;
		int d;
		c = ++b;
		d = a++;
		c++;
		System.out.println("a = " + a);
		System.out.println("b = " + b);
		System.out.println("c = " + c);
		System.out.println("d = " + d);
	}
}

4-12
class BoolLogic {
	public static void main(String args[]) {
		boolean a = true;
		boolean b = false;
		boolean c = a | b;
		boolean d = a & b;
		boolean e = a ^ b;
		boolean f = (!a & b) | (a & !b);
		boolean g = !a;
		System.out.println(" 		a 	= " + a);
		System.out.println(" 		b 	= " + b);
		System.out.println(" 		a|b 	= " + c);
		System.out.println(" 		a&b 	= " + d);
		System.out.println(" 		a^b 	= " + e);
		System.out.println("!a&b|a&!b 	= " + f);
		System.out.println("		!a 	= " + g);
	}
}

4-13
class Ternary {
	public static void main(String args[]) {
		int i, k;
		i = 10;
		k = i < 0 ? -i : i; // get absolute value of i
		System.out.print("Absolute value of ");
		System.out.println(i + " is " + k);
		i = -10;
		k = i < 0 ? -i : i; // get absolute value of i
		System.out.print("Absolute value of ");
		System.out.println(i + " is " + k);
	}
}

4-14
class OpBitEquals {
	public static void main(String args[]) {
		int a = 1;
		int b = 2;
		int c = 3;
		a |= 4;
		b >>= 1;
		c <<= 1;
		a ^= c;
		System.out.println("a = " + a);
		System.out.println("b = " + b);
		System.out.println("c = " + c);
	}
}



4-15
import  java.io.*;
public  class  HelloWorld {
	public  static  void  main(String  args[])
	{
		char c='a';
		System.out.print("Enter  a  character  please  ");
		try
		{
			c=(char)System.in.read();
		}
		catch  (IOException  e)
		{	
		}
			System.out.println("you've  entered  character  "+c);
	}
}


4-16
import java.io.*;
import javax.swing.*;

public class one extends JFrame {
	one() {
	}

	public void makewarning(String warning) {
		JOptionPane.showMessageDialog(this, warning, "Ի",
				JOptionPane.WARNING_MESSAGE);
	}

	public static void main(String args[]) {
		one show = new one();
		show.makewarning("");
	}
}
