一.下列语句哪一个将引起编译错误?为什么?哪一个会引起运行时错误?为什么?
m=d; d=m; d=(Dog)m; d=c; c=(Cat)m;
d=m;和d=c;引起编译错误；
原因：
二.CatchWho.java
源代码：
public class CatchWho { public static void main(String[] args) { try { try { throw new ArrayIndexOutOfBoundsException(); } catch(ArrayIndexOutOfBoundsException e) { System.out.println( "ArrayIndexOutOfBoundsException" + "/内层try-catch"); } throw new ArithmeticException(); } catch(ArithmeticException e) { System.out.println("发生ArithmeticException"); } catch(ArrayIndexOutOfBoundsException e) { System.out.println( "ArrayIndexOutOfBoundsException" + "/外层try-catch"); } } } 
三.CatchWho2.java
源代码：
public class CatchWho2 { public static void main(String[] args) { try { try { throw new ArrayIndexOutOfBoundsException(); } catch(ArithmeticException e) { System.out.println( "ArrayIndexOutOfBoundsException" + "/内层try-catch"); } throw new ArithmeticException(); } catch(ArithmeticException e) { System.out.println("发生ArithmeticException"); } catch(ArrayIndexOutOfBoundsException e) { System.out.println( "ArrayIndexOutOfBoundsException" + "/外层try-catch"); } } } 
四.EmbededFinally.java
源代码：
public class EmbededFinally { public static void main(String args[]) { int result; try { System.out.println("in Level 1"); try { System.out.println("in Level 2"); // result=100/0; //Level 2 try { System.out.println("in Level 3"); result=100/0; //Level 3 } catch (Exception e) { System.out.println("Level 3:" + e.getClass().toString()); } finally { System.out.println("In Level 3 finally"); } // result=100/0; //Level 2 } catch (Exception e) { System.out.println("Level 2:" + e.getClass().toString()); } finally { System.out.println("In Level 2 finally"); } // result = 100 / 0; //level 1 } catch (Exception e) { System.out.println("Level 1:" + e.getClass().toString()); } finally { . System.out.println("In Level 1 finally"); } }} 
五.课后作业
源代码：
package zuoye3;import java.util.Scanner;public class Fenshu { public static void main(String[] args) { int s = 0,a=0; System.out.println("请输入分数"); Scanner b=new Scanner(System.in); try { s=Integer.parseInt(b.next()); if(s>90&&s<=100){ a=1; }else if(s>80&&s<=90){ a=2; }else if(s>70&&s<=80){ a=3; }else if(s>60&&s<=70){ a=4; }else if(s>=0&&s<=60){ a=5; } switch(a) { case 1: { System.out.println("优"); break; } case 2: { System.out.println("良"); break; } case 3: { System.out.println("中"); break; } case 4: { System.out.println("及格"); break; } case 5: { System.out.println("不及格"); break; } } } catch(Exception e){ System.out.println("错误"); }} } 
