Java语言程序设计（基础篇）原书第十一版 梁勇 第12章 课后题答案

12.2

public class DemoA {

public static void main(String[] args) { Scanner in=new Scanner(System.in); boolean start=true; while (start){ try{

System.out.println(\请输入两个整数：\ int a=in.nextInt(); int b=in.nextInt();

System.out.println(\ break;

}catch(InputMismatchException e){

System.out.println(\输入错误，请重新输入！\ in.nextLine(); } } } }

12.6

public class HexDec {

public static void main(String[] args) { try{

Scanner in=new Scanner(System.in);

System.out.println(\请输入一个16进制字符串：\ String hex=in.next(); judge(hex);

System.out.println(\十进制数为：\ }catch(NumberFormatException e){ System.out.println(e.getMessage()); } }

public static void judge(String str){ for (int i=0;i

if ((47

System.out.println(a);

throw new NumberFormatException(\请输入正确的16进制数\ } }

public static int hexToDecimal(String hex){ int decimalValue=0;

for (int i=0;i

decimalValue=decimalValue*16+hexCharToDecimal(hexChar); }

return decimalValue; }

public static int hexCharToDecimal(char ch){ if (ch>='A'&&ch<='F') return 10+ch-'A'; else return ch-'0'; } }