解析Java程序设计答案

java作业 5. 答：由于第一个catch子句将捕获所有异常，因此，第二个catch子句永远不会被执行。不能通过编译。 6. 答： public class first_exception { public static void main(String args[]){ char c; int a,b=0; int[] array=new int[7]; String s=“Hello“; try{ a=1/b; } catch(ArithmeticException ae){ System.out.println(“Catch “+ae); } try{ array[8]=0; } catch(ArrayIndexOutOfBoundsException ai){ System.out.println(“Catch “+ai); } try{ c=s.charAt(8); }catch(StringIndexOutOfBoundsException se){ System.out.println(“Catch “+se); } } } 运行结果： Catch java.lang.ArithmeticException: / by zero Catch java.lang.ArrayIndexOutOfBoundsException: 8 Catch java.lang.StringIndexOutOfBoundsException: String index out of range: 8 9. 答： import java.util.Scanner; public class Test{ public static class Num{ public static void main(String[] args){ @SuppressWarnings(“resource“) Scanner sc=new Scanner(System.in); System.out.println(“Please Zero to Nine!“); String str=sc.nextLine(); if(str.equalsIgnoreCase(“Zero“)){ System.out.println(str + “ to number is: “ + 0); } else if(str.equalsIgnoreCase(“One“)){ System.out.println(str + “ to number is: “ + 1); } else if(str.equalsIgnoreCase(“Two“)){ System.out.println(str + “ to number is: “ + 2); } else if(str.equalsIgnoreCase(“Three“)){ System.out.println(str + “ to number is: “ + 3); } else if(str.equalsIgnoreCase(“Four“)){ System.out.println(str + “ to number is: “ + 4); } else if(str.equalsIgnoreCase(“Five“)){ System.out.println(str + “ to number is: “ + 5); } else if(str.equalsIgnoreCase(“Six“)){ System.out.println(str + “ to number is: “ + 6); } else if(str.equalsIgnoreCase(“Seven“)){ System.out.println(str+ “ to number is: “ + 7); } else if(str.equalsIgnoreCase(“Eight“)){ System.out.println(str + “ to number is: “ + 8); } else if(str.equalsIgnoreCase(“Nine“)){ System.out.println(str + “ to number is: “ + 9); } else try{ throw new Exception(“无匹配“);} catch (Exception e) { system.out.println(“错误的输入！“)；} } } } 运行结果1： Please Zero to Nine! Hjg 错误的输入！ 运行结果2： Please Zero to Nine! One One to number is: 1 12. 答： public class MyException extends Exception{ public MyException(String msg){ super(msg); } } public class PhoneNumber { public static boolean check(String s) throws MyException{ { String number; number=s; if(number.length()>12) { throw new MyException(“电话号码不能超过12位“); } char a=number.charAt(0); if(a>0) { throw new MyException(“区号只能以0开头“); public static void main(String args[]) throws MyException { @SuppressWarnings(“unused“) String s = “1