System.out.println(y); //static总是最新,一个备份 } }
和命令行: java TestMain
结果为: A. 3 B. 5 C. 编译失败 D. 运行时异常被抛出
答案: B
57.现有:
1. interface Animal { 2. void eat(); 3. } 4.
5. // insert code here 6.
7. public class HouseCat implements Feline { 8. public void eat() { } 9. }
和以下三个接口声明:
interface Feline extends Animal { }
interface Feline extends Animal { void eat(); interface Feline extends Animal { void eat()
分别插入到第 5 行,有多少行可以编译? A. 0 B. 1
} } } { C. 2 D. 3
答案: C
58.现有: 1. class Book {
2. private final void read() { System.out.print(\3. }
4. class Page extends Book {
5. public static void main(String [] args) { 6. // insert code here 7. }
8. private final void read() { System.out.print(\9. }
和如下三个代码片段( x, y, z ): x. // just a comment y. new Page().read(); z. new Book().read();
分别插入到第6行,有几个允许代码通过编译并可以运行且无异常? A. 0 B. 1 C. 2 D. 3 答案:C
59.Java语言中异常的分类是哪项?:::受检异常和非受检异常
E. 受检异常和非受检异常 F. 运行时异常和异常 G. 错误和异常
H. 错误和运行时异常
答案: A
60.所有异常的父类是哪项? Throwable
A. Exception B. Error
C. RuntimeException D. Throwable 答案:D
61.关于try...catch...finally结构,描述正确的是哪项?可以有多个catch,也可以没有catch(选两项) A. 可以有多个catch B. 只能有一个catch C. finally必须有 D. 可以没有catch
答案:A D
62.public class TestApp{
public static void main(String[] args){ try{
String myname = null; if(myname.length()>2) System.out.print(“1”); }catch(NullPointerException e){ System.out.print(“2”); } } }
上述程序运行后的输出是哪项? A. 1 B. 12 C. 21 D. 2
答案: D
63.public class TestApp{
public static void main(String[] args){ try{
int i = 0; int j = 1 / i; String myname=null; if(myname.length()>2) System.out.print(“1”); }catch(NullPointerException e){ System.out.print(“2”); }
catch(Exception e){
System.out.print(“3”); } } }
上述程序运行后的输出是哪项? A. 3 B. 2 C. 231 D. 32
答案: A
64.public class TestApp{
public static void main(String[] args){ try{
int i = 0; int j = 1 / i;
System.out.println(“1”); }catch(Exception e){ System.out.print(“3”); }finally{
System.out.print(“4”); } } }
上述程序运行后的输出是哪项? A. 4 B. 34 C. 43 D. 14
答案: B
65.public class TestApp{ public int mymethod(){ try{
int i = 0; int j = 1 / i;
System.out.println(“1”); }finally{
System.out.print(“4”); }
return 1; } }
上述程序运行后的输出是哪项? A. 4