java语言程序设计 第十二章（12.7、12.8、12.9）

import java.util.Scanner;

public class BinaryToDex
{
public static void main(String [] args)
{
Scanner input = new Scanner(System.in);
try
{
System.out.print("Enter a binary string: ");
String str = input.next();
System.out.println("The binary value for decimal number " + str + " is " + bin2Dex(str));
}
catch (NumberFormatException ex)
{
System.out.println(ex.getMessage() + " not a decimal string");
}

}

public static int bin2Dex(String str) throws NumberFormatException
{
int result = 0;
for (int i = str.length() - 1; i >= 0; i--)
{
if (!(str.charAt(i) == '0' || str.charAt(i) == '1'))
{
throw new NumberFormatException(str);
}
else
result += Math.pow(2, (str.length() - i - 1)) * (str.charAt(i) - '0');
}

return result;
}
}

public class HexFormatException extends Exception
{
String hexString;

public HexFormatException(String hexString)
{
super("HexFormatException: " + hexString);
this.hexString = hexString;
}

public String getHexString()
{
return hexString;
}
}

import java.util.Scanner;

public class HexToDecUseHexFormatException
{
String hexString;

public HexToDecUseHexFormatException(String hexString)
throws HexFormatException
{
setHexString(hexString);
}

public void setHexString(String hexString)
throws HexFormatException
{
for (int i = 0; i < hexString.length(); i++)
{
if (judge(hexString.charAt(i)) == -1)
{
throw new HexFormatException(hexString + " is not a hex string");
}
}

this.hexString = hexString;
}

public String getHexString()
{
return hexString;
}

private int judge(char ch)
{
if ((ch >= '0') && (ch <= '9'))
{
return (ch - '0');
}
else if ((ch >= 'A') && (ch <= 'F'))
{
return (ch - 'A' + 10);
}
else
return -1;
}

public int hexToDec()
{
int result = 0;
for (int i = hexString.length() - 1; i >= 0; i--)
{
result += judge(hexString.charAt(i)) * (Math.pow(16, (hexString.length() - i - 1)));
}
return result;
}
}

import java.util.Scanner;

public class TestHexFormatException
{
public static void main(String [] args)
{
Scanner input = new Scanner(System.in);
try
{
System.out.print("Enter a hex string: ");
HexToDecUseHexFormatException hex =
new HexToDecUseHexFormatException(input.next());
System.out.println("The decimal value for hex number "
+ hex.getHexString() + " is " + hex.hexToDec());
}
catch (HexFormatException ex)
{
System.out.println(ex.getMessage());
}
}
}

public class  BinaryFormatException extends Exception
{
String binString;

public BinaryFormatException(String binString)
{
super(binString);
this.binString = binString;
}

public String getBinString()
{
return binString;
}
}

public class Bin2DecUseBinaryFormatException
{
String binString;

public  Bin2DecUseBinaryFormatException(String binString)
throws BinaryFormatException
{
setBinString(binString);
}

public void setBinString(String binString)
throws BinaryFormatException
{
for (int i = 0; i <  binString.length(); i++)
{
if ((binString.charAt(i) != '0') && (binString.charAt(i) != '1'))
{
throw new BinaryFormatException(binString + " is not a binary string");
}
}

this.binString = binString;
}

public String getBinString()
{
return binString;
}

public int bin2Dec()
{
int result = 0;
for (int i = binString.length() - 1; i >= 0; i--)
{
result += (binString.charAt(i) - '0') * Math.pow(2, binString.length() - i - 1);
}

return result;
}
}

import java.util.Scanner;

public class TestBin2DecUseBinaryFormatException
{
public static void main(String [] args)
{
Scanner input = new Scanner(System.in);
try
{
System.out.print("Enter a bin string: ");
Bin2DecUseBinaryFormatException bin = new
Bin2DecUseBinaryFormatException(input.next());
System.out.println("The binary value for decimal number " +
bin.getBinString() + " is " + bin.bin2Dec());
}
catch (BinaryFormatException ex)
{
System.out.println(ex.getMessage());
}
}
}