课后作业

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");
        
    }
}
    
}