3.txt

电子工业出版社出版的《java2应用开发指南》配套光盘源代码

例程3-1
//Circle.java
public class Circle
{
   //定义程序运行常量π的值
	public static final double PAI = 3.14;
   //定义成员变量：圆的半径
   public static double radius;
   //类的构造函数
   public Circle( double radius)
   {
		Circle.radius = radius;
   }
   //类的方法成员
   public static double getArea()
   {
		return radius*radius*PAI;
   }
	public static void main(String[] args)
	{
		Circle aCircle = new Circle( 2.0 );
		double area = Circle.getArea();
		System.out.println("圆的面积是："+ area);
		System.exit(0);
	}
}



例程3-2
//VariableDemo.java
public class VariableDemo
{
	public VariableDemo()
	{
	}
	public void memberForIllustration()
	{
	 	int      nIntegerValue = 10;
	    double   dDoubleValue = 3.14;
	    char     cCharValue = 'a';
	    boolean  bBoolen = false;
	    System.out.println("整数变量："+nIntegerValue+ "双精度变量："+dDoubleValue+ "字符变量："+ cCharValue);
	}
	public static void main(String[] args)
	{
		VariableDemo  aVariableDemo = new VariableDemo();
	    aVariableDemo.memberForIllustration();
	}
}



例程3-3
//IntDemo.java
class IntDemo
{
    public static int MAXINTEGER = 100;
	public IntDemo()
	{
	}
	public void demoUsing()
	{
	    byte     btByteValue = 5;
	 	int      nIntegerValue = 10;
	    short    sShortCalue = 20;
	    long     lLongValue=0;
	
       	for(;;)
       	{
			lLongValue = lLongValue + btByteValue;
			lLongValue = lLongValue + nIntegerValue;
			lLongValue = lLongValue + sShortCalue;
           if( lLongValue > MAXINTEGER )
             break;
       	}
	    System.out.println("在本程序中整数变量的最大值：" +lLongValue);
	}
	public static void main(String[] args)
	{
		IntDemo aIntDemo = new IntDemo ();
	    aIntDemo.demoUsing ();
	}
}



例程3-4
//RealDemo.java
class RealDemo
{
	public static float fPAI = 3.14f;
	public float fRadius;
	public double dTotalLength;
	public RealDemo( float fRadius )
	{	
		this.fRadius = fRadius;
	}
	public double computeLength()
	{
		dTotalLength = 2*fPAI*fRadius;
	    return dTotalLength;
	}
	public static void main(String[] args)
	{
		RealDemo aRealDemo = new RealDemo( 5 );
	   	double dLength = aRealDemo.computeLength();
	   	System.out.println("计算获得的圆的周长为："+dLength);
	}
}



例程3-5
// VariableTypeDemo.Java
class  VariableTypeDemo
{
   //计数器成员变量
   public int nCounter;
   //部分量成员变量
   public float fStep;
   //总成员变量
   public double dTotal;
   //标志字
   public boolean bFlag;
   //字符成员变量
   public char  cYesOrNo;
   //构造函数
   public VariableTypeDemo(int nCounter, float fStep, double dTotal, char  cYesOrNo)
   {
       //根据构造函数的参数，将成员变量初始化赋值
		this.nCounter = nCounter;
       this.fStep = fStep;
       this.dTotal = dTotal;
       this.cYesOrNo = cYesOrNo;
   }
   //取得累加结果的方法
   public double getTotal()
   {
		return dTotal;
   }
   public double processAccumulate()
   {
       //循环累加，同时计数器nCounter等于100作为循环终止条件
		for( int i=0; i<nCounter; i++)
       {
          //判断当前的累加条件
			if( cYesOrNo == 'N' || !bFlag ) 
                break;
          //累加
          dTotal += fStep;
          //累加终止条件
          if( dTotal >= 300 ) bFlag = false;
       }
       return dTotal;
   } 
   //Java应用程序的main方法
	public static void main(String args[])
   {
       //生成类Variable的实例
		VariableTypeDemo usrVariable = new VariableTypeDemo(100,15,0,'y');
       //调用实例方法
       usrVariable.processAccumulate();
       //调用实例方法
		double result = usrVariable.getTotal();
       System.out.println("经过累加后，小于界限的结果为："+result);
   }
}



例程3-6
//convention.java
class Convention
{
     public static void main( String args[ ] )
     {
	    byte bByte = 2;
	    char cChar = 'c';
	    int nInt = 10;
	    float fFloat = 3.5f;
	    double dDouble = 1.234;
	 
	    //float OP byte ->float
	    float fFloatNew = fFloat + bByte;
	    //char OP int ->int
	    int nIntNew = cChar + nInt;
	    //float OP double ->double
	    double dDoubleNew = fFloatNew/nInt;
	 }
}