课后作业---字符串

package T4;

//胡建峰，2016.10.25
//字串加密

import java.util.Scanner;

public class Test {
	
	public static void main( String args[] ){		
		Scanner N = new Scanner(System.in);//输入
		System.out.print("请输入要执行操作（1.加密，2解密）：");
		int choose = N.nextInt();
		String result="";
		char temp;
		
		if(choose == 1)//加密
		{
			System.out.print("请输入字符串:");
			String wen = N.next();
			for(int i = 0;i < wen.length();i++)
			{
				if((wen.charAt(i) > 64 && wen.charAt(i) < 88)||(wen.charAt(i) > 98 && wen.charAt(i) < 120))
					temp=(char) (wen.charAt(i) + 3);
				else if((wen.charAt(i) > 87 && wen.charAt(i) < 91)||(wen.charAt(i) > 119 && wen.charAt(i) < 123))
					temp=(char) (wen.charAt(i) - 23);
				else
				{
					System.out.println("中间输入有误!");
					break;
				}			
				result += temp;
			}
			System.out.println("加密后结果为:" + result);
		}
		else if(choose == 2)//解密
		{
			System.out.print("请输入字符串:");
			String wen = N.next();
			for(int i = 0;i < wen.length();i++)
			{
				if((wen.charAt(i) > 67 && wen.charAt(i) < 91)||(wen.charAt(i) > 99 && wen.charAt(i) < 123))
					temp=(char) (wen.charAt(i) - 3);
				else if((wen.charAt(i) > 64 && wen.charAt(i) < 68)||(wen.charAt(i) > 96 && wen.charAt(i) < 100))
					temp=(char) (wen.charAt(i) + 23);
				else
				{
					System.out.println("中间输入有误!");
					break;
				}			
				result += temp;
			}
			System.out.println("解密后结果为:" + result);
		}
		else
			System.out.println("输入有误！");
		N.close();
	}
}