1考java基础.docx

1、1考java基础一、 单选(30小题共60.0分)1.类A，B的定义如下：class A private int a = 100; A() System.out.print(A(); System.out.println(a); class B extends A private int a = 200; B() System.out.print(B(); System.out.println(a); 运行下面的代码：new B();输出的结果是：（）。A. A() 100B() 200B. A() 200B() 200C. B() 200A() 100D. B() 200A() 2002.下

2、列代码编译和运行的结果是：public static void main(String args) Float pi = new Float(3.14f); if (pi 3) System.out.print(pi is bigger than 3. ); else System.out.print(pi is not bigger than 3. ); finally System.out.println(Have a nice day.); A. 编译失败B. 输出：pi is bigger than 3.C. 输出：pi is bigger than 3. Have a nice da

3、yD. 输出：pi is not bigger than 3. Have a nice day.3.下列属于不合法Java标识符的是（）。A. _memB. 12aC. M12D. $124.下列代码的运行结果是： String test = Test A. Test B. Test C.; String regex = .s*; String result = test.split(regex); for (String s : result) System.out.print(s + );A. Test A Test B Test CB. Test A. Test B. Test C.C.

4、 Test . Test . Test .D. A. B. C.5.类Super及Sub定义如下：public class Super private void f() System.out.println(Super.f(); public void g() f(); public void k() f(); public class Sub extends Super private void f() System.out.println(Sub.f(); public void k() f(); 运行下列语句:Super obj = new Sub();obj.g();obj.k();输

5、出的结果是：（）。A. Sub.f()Sub.f()B. Sub.f()Super.f()C. Super.f()Sub.f()D. Super.f()Super.f()6.下列代码的运行结果是（）。public class Forest implements Serializable private Tree tree = new Tree(); public static void main(String args) Forest f = new Forest(); try FileOutputStream fs = new FileOutputStream(Forest.ser); Ob

6、jectOutputStream os = new ObjectOutputStream(fs); os.writeObject(f); os.close(); catch (Exception ex) ex.printStackTrace(); class Tree A. 编译失败B. 运行时,抛出异常C. Forest的实例被序列化到文件D. Forest的实例和Tree的实例都被序列化到文件7.运行下列代码，输出为false的是：（）。A. String st1 = abc;System.out.println(abc = st1);B. String st2 = abc;System.

7、out.println(st2.equals(new String(abc);C. Integer i = 100;System.out.println(100 = i);D. ArrayList list = new ArrayList();System.out.println(list.contains(null);8.类A，B和C的定义如下：public class A public void f() System.out.println(A.f(); public class B extends A public void f() System.out.println(B.f(); p

8、ublic class C public void g(A a) System.out.println(g(A a); a.f(); public void g(B b) System.out.println(g(B b); b.f(); 运行下面程序: C c = new C(); A a = new B(); c.g(a);输出的结果是：（）。A. g(A a)A.f()一、 单选(30小题共60.0分)1.类A，B的定义如下：class A private int a = 100; A() System.out.print(A(); System.out.println(a); clas

9、s B extends A private int a = 200; B() System.out.print(B(); System.out.println(a); 运行下面的代码：new B();输出的结果是：（）。A. A() 100B() 200B. A() 200B() 200C. B() 200A() 100D. B() 200A() 2002.下列代码编译和运行的结果是：public static void main(String args) Float pi = new Float(3.14f); if (pi 3) System.out.print(pi is bigger

10、than 3. ); else System.out.print(pi is not bigger than 3. ); finally System.out.println(Have a nice day.); A. 编译失败B. 输出：pi is bigger than 3.C. 输出：pi is bigger than 3. Have a nice dayD. 输出：pi is not bigger than 3. Have a nice day.3.下列属于不合法Java标识符的是（）。A. _memB. 12aC. M12D. $124.下列代码的运行结果是： String test

11、 = Test A. Test B. Test C.; String regex = .s*; String result = test.split(regex); for (String s : result) System.out.print(s + );A. Test A Test B Test CB. Test A. Test B. Test C.C. Test . Test . Test .D. A. B. C.5.类Super及Sub定义如下：public class Super private void f() System.out.println(Super.f(); publ

12、ic void g() f(); public void k() f(); public class Sub extends Super private void f() System.out.println(Sub.f(); public void k() f(); 运行下列语句:Super obj = new Sub();obj.g();obj.k();输出的结果是：（）。A. Sub.f()Sub.f()B. Sub.f()Super.f()C. Super.f()Sub.f()D. Super.f()Super.f()6.下列代码的运行结果是（）。public class Forest

13、 implements Serializable private Tree tree = new Tree(); public static void main(String args) Forest f = new Forest(); try FileOutputStream fs = new FileOutputStream(Forest.ser); ObjectOutputStream os = new ObjectOutputStream(fs); os.writeObject(f); os.close(); catch (Exception ex) ex.printStackTrac

14、e(); class Tree A. 编译失败B. 运行时,抛出异常C. Forest的实例被序列化到文件D. Forest的实例和Tree的实例都被序列化到文件7.运行下列代码，输出为false的是：（）。A. String st1 = abc;System.out.println(abc = st1);B. String st2 = abc;System.out.println(st2.equals(new String(abc);C. Integer i = 100;System.out.println(100 = i);D. ArrayList list = new ArrayList

15、();System.out.println(list.contains(null);8.类A，B和C的定义如下：public class A public void f() System.out.println(A.f(); public class B extends A public void f() System.out.println(B.f(); public class C public void g(A a) System.out.println(g(A a); a.f(); public void g(B b) System.out.println(g(B b); b.f();

16、 运行下面程序: C c = new C(); A a = new B(); c.g(a);输出的结果是：（）。A. g(A a)A.f()B. g(A a)B.f()C. g(B b)A.f()D. g(B b)B.f()9.运行下面的程序：Calendar c = Calendar.getInstance();c.set(Calendar.YEAR, 2012);c.set(Calendar.MONTH, Calendar.SEPTEMBER);c.set(Calendar.DATE, 31);SimpleDateFormat sdf = new SimpleDateFormat(yyyy

17、-MM-dd);System.out.println(sdf.format(c.getTime();输出的结果是：（）。A. 2012-10-1B. 2012-10-01C. 2012-09-30D. 2012-9-3010.请看下列代码编译和运行的结果是（）。interface DeclareStuff public static final int EASY = 3; void doStuff(int t);public class TestDeclare implements DeclareStuff public static void main(String args) int x

18、= 5; new TestDeclare().doStuff(+x); void doStuff(int s) s += EASY + +s; System.out.println(s= + s); A. s=14B. s=16C. s=10D. 编译失败11.需要读取一个比较大的文本文件，这个文件里有很多字节的数据，那么下列最合适读这个文件的选项是：（）。A. new FileInputStream(“fileName”);B. new InputStreamReader(new FileInputStream(“fileName”);C. new BufferedReader(new In

19、putStreamReader(new FileInputStream(“fileName”);D. new RandomAccessFile(“fileName”,”+rw”);12.请看下列代码： public static void main(String args) Date d = new Date(0); String ds = December 15, 2004; DateFormat df= DateFormat.getDateInstance(); try d = df.parse(ds); catch (ParseException e) System.out.printl

20、n(Unable to parse + ds); d.setTime( (1000 * 60 * 60 * 24) + d.getTime();在处创建一个DateFormat对象，在处给Date对象d加上一天，下列选项正确的是：A. DateFormat df= DateFormat.getDateFormat();d.setTime( (60 * 60 * 24) + d.getTime();B. DateFormat df= DateFormat.getDateInstance();d.setTime( (1000 * 60 * 60 * 24) + d.getTime();C. Dat

21、eFormat df= DateFormat.getDateFormat();d.setLocalTime( (1000*60*60*24) + d.getLocalTime();D. DateFormat df= DateFormat.getDateInstance();d.setLocalTime( (60 * 60 * 24) + d.getLocalTime();13.下列代码的输出结果是：public static void main(String args) BigDecimal d1 = new BigDecimal(3.0); BigDecimal d2 = new BigDe

22、cimal(2.9); BigDecimal d3 = d1.subtract(d2); System.out.println(d3);A. 0B. 0.1C. 0.10000000000000009D. 0.1014.下列赋值语句中，正确的是（）。A. byte b1 = 10, b2 = 20;byte b=b1+b2;B. byte b1 = 10, b2 = 20;byte b=b1;C. byte b1 = 10, b2 = 20;byte b=b11;D. byte b1 = 10;byte b=+b1;15.下列代码的输出结果是：public class Yikes public

23、 static void go(Long n) System.out.println(Long );public static void go(Short n) System.out.println(Short );public static void go(int n) System.out.println(int );public static void main(String args) short y = 6; long z = 7; go(y); go(z);A. LongLongB. ShortLongC. intLongD. intint16.IO 包中，唯一代表磁盘本身的对象类是（）。A. FileInputStream B. FileC. InputStream D. BufferedReader17.仔细分析下列代码，请指出错误的行（）。public class SomeThing private String str; public int addOne(final int x) return +x; A. public class SomeThingB. private String st