Java基础
1. Which of the following will compile correctly?
A) float f=10f; B) float f=10.1; C) float f=10.1f; D) byte b=10b;
2. Which declarations of identifiers are legal A. $persons B. TwoUsers C. *point D. this E. _endline
3. Which statement of assigning a long type variable to a hexadecimal value is correct A. long number = 345L; B. long number = 0345; C. long number = 0345L; D. long number = 0x345L
4. Which of the following fragments might cause errors A. String s = \"Gone with the wind\"; String t = \" good \"; String k = s + t;
B. String s = \"Gone with the wind\"; String t;
t = s[3] + \"one\";
C. String s = \"Gone with the wind\"; String standard = s.toUpperCase();
D. String s = \"home directory\"; String t = s - \"directory\";
5. Which are syntactically valid statement at// point x class Person { private int a;
public int change(int m){ return m; } }
public class Teacher extends Person { public int b;
public static void main(String arg[]){ Person p = new Person(); Teacher t = new Teacher(); int i; // point x } }
A. i = m; B. i = b; C. i = p.a;
D. i = p.change(30); E. i = t.b.
6. Which layout manager is used when the frame is resized the buttons's position in the Frame might be changed A. BorderLayout B. FlowLayout C. CardLayout D. GridLayout
7. Given the following code fragment: 1) public void create() { 2} Vector myVect;
3} myVect = new Vector(); 4} }
Which of the following statements are true
A. The declaration on line 2 does not allocate memory space for the variable myVect. B. The declaration on line 2 allocates memory space for a reference to a Vector object. C. The statement on line 2 creates an object of class Vector. D. The statement on line 3 creates an object of class Vector.
E. The statement on line 3 allocates memory space for an object of class Vector
8. Which of the following answer is correct to express the value 8 in octal number A. 010 B. 0x10 C. 08 D. 0x8
9. Which are not Java keywords A. TRUE B. sizeof C. const
D. super E. void
10. Which of the following statements are true
A. The equals() method determines if reference values refer to the same object.
B. The == operator determines if the contents and type of two separate objects match. C. The equals() method returns true only when the contents of two objects match.
D. The class File overrides equals() to return true if the contents and type of two separate objects match.
11. Which statements about inheritance are true
A. In Java programming language only allows single inheritance.
B. In Java programming language allows a class to implement only one interface.
C. In Java programming language a class cannot extend a class and implement a interface together.
D. In Java programming language single inheritance makes code more reliable. 12.
1) class Person {
2} public void printValue(int i, int j) {/*…*/ } 3} public void printValue(int i){/*...*/ } 4} }
5) public class Teacher extends Person { 6} public void printValue() {/*...*/ } 7} public void printValue(int i) {/*...*/} 8} public static void main(String args[]){ 9} Person t = new Teacher(); 10} t.printValue(10); 11} } 12} }
Which method will the statement on line 10 call A. on line 2 B. on line 3 C. on line 6 D. on line 7
13. Which are not Java primitive types A. short B. Boolean C. unit D. float
14、The method resume() is responsible for resuming which thread's execution A. The thread which is stopped by calling method stop() B. The thread which is stopped by calling method sleep() C. The thread which is stopped by calling method wait()\\ D. The thread which is stopped by calling method suspend()
15. Which of the following range of int is correct A. -2^7 – 2^7-1 B. 0 – 2^32-1 C. -2^15 – 2^15-1 D. -2^31 – 2^31-1
16. Which keyword should be used to enable interaction with the lock of an object The flag allows exclusive access to that object. A. transient B. synchronized C. serialize D. static
17. Which is the return type of the method main() A. int B. void C. boolean D. static
18. Given the following code:
if (x>0) { System.out.println(\"first\"); }
else if (x>-3) { System.out.println(\"second\"); } else { System.out.println(\"third\"); }
Which range of x value would print the string \"second\" A. x > 0 B. x > -3 C. x <= -3
D. x <= 0 & x > -3
19、Which of the following answer is correct to express the value 10 in hexadecimal number A. 0xA B. 0x16 C. 0A D. 016
20. Which statements about the garbage collection are true
A. The program developer must create a thread to be responsible for free the memory.
B. The garbage collection will check for and free memory no longer needed. C. The garbage collection allow the program developer to explicity and immediately free the memory.
D. The garbage collection can free the memory used java object at expect time.
21、Given the following code: 1) public class Test { 2} int m, n;
3} public Test() {}
4} public Test(int a) { m=a; }
5} public static void main(String arg[]) { 6} Test t1,t2; 7} int j,k; 8} j=0; k=0;
9} t1=new Test(); 10} t2=new Test(j,k); 11} } 12} }
Which line would cause one error during compilation A. line 3 B. line 5 C. line 6 D. line 10
22、Given the uncompleted code of a class: class Person {
String name, department; int age;
public Person(String n){ name = n; }
public Person(String n, int a){ name = n; age = a; } public Person(String n, String d, int a) {
// doing the same as two arguments version of constructor // including assignment name=n,age=a department = d; } }
Which expression can be added at the \"doing the same as...\" part of the constructor
A. Person(n,a);
B. this(Person(n,a)); C. this(n,a);
D. this(name,age).
23、Which of the following statements about variables and their scopes are true A. Instance variables are member variables of a class. B. Instance variables are declared with the static keyword.
C. Local variables defined inside a method are created when the method is executed. D. Local variables must be initialized before they are used.
24、public void test() { try { oneMethod();
System.out.println(\"condition 1\");
} catch (ArrayIndexOutOfBoundsException e) { System.out.println(\"condition 2\"); } catch(Exception e) {
System.out.println(\"condition 3\"); } finally {
System.out.println(\"finally\"); } }
Which will display if oneMethod run normally A. condition 1 B. condition 2 C. condition 3 D. finally
25、Given the following code: public class Test {
void printValue(int m){
do { System.out.println(\"The value is\"+m); }
while( --m > 10 ) }
public static void main(String arg[]) { int i=10;
Test t= new Test(); t.printValue(i); } }
Which will be output A. The value is 8 B. The value is 9 C. The value is 10 D. The value is 11
26、Which of the following statements about declaration are true
A. Declaration of primitive types such as boolean, byte and so on does not allocate memory space for the variable.
B. Declaration of primitive types such as boolean, byte and so on allocates memory space for the variable.
C. Declaration of nonprimitive types such as String, Vector and so on does not allocate memory space for the object.
D. Declaration of nonprimitive types such as String, Vector ans so on allocates memory space for the object.
27、In the Java API documentation which sections are included in a class document
A. The description of the class and its purpose B. A list of methods in its super class C. A list of member variable D. The class hierarchy
28、Given the following code: 1) public void modify() { 2) int i, j, k; 3) i = 100;
4) while ( i > 0 ) { 5) j = i * 2;
6) System.out.println (\" The value of j is \" + j ); 7) k = k + 1; 8) i--; 9) } 10} }
Which line might cause an error during compilation A. line 4 B. line 6 C. line 7 D. line 8
29、Which of the following statements about variables and scope are true
A. Local variables defined inside a method are destroyed when the method is exited. B. Local variables are also called automatic variables.
C. Variables defined outside a method are created when the object is constructed.
D. A method parameter variable continues to exist for as long as the object is needed in which the method is defined.
30、A class design requires that a member variable cannot be accessible directly outside the class. Which modifier should be used to obtain the access control A. public
B. no modifier C. protected D. private
31、Given the following code fragment: 1) String str = null;
2) if ((str != null) && (str.length() > 10)) { 3} System.out.println(\"more than 10\"); 4} }
5) else if ((str != null) & (str.length() < 5)) { 6} System.out.println(\"less than 5\"); 7} }
8) else { System.out.println(\"end\"); } Which line will cause error A. line 1 B. line 2 C. line 5 D. line 8
32、Which statements about Java code security are true
A. The bytecode verifier loads all classes needed for the execution of a program. B. Executing code is performed by the runtime interpreter.
C. At runtime the bytecodes are loaded, checked and run in an interpreter.
D. The class loader adds security by separating the namespaces for the classes of the local file system from those imported from network sources.
33、 Given the following code: public class Person{ int arr[] = new int[10];
public static void main(String a[]) { System.out.println(arr[1]); } }
Which statement is correct
A. When compilation some error will occur.
B. It is correct when compilation but will cause error when running. C. The output is zero. D. The output is null.
34、public class Parent {
public int addValue( int a, int b) { int s; s = a+b; return s; } }
class Child extends Parent { }
Which methods can be added into class Child A. int addValue( int a, int b ){// do something...} B. public void addValue (){// do something...} C. public int addValue( int a ){// do something...}
D. public int addValue( int a, int b )throws MyException {//do something...}
35、Which statements about thread are true
A. Once a thread is created, it can star running immediately.
B. To use the start() method makes a thread runnable, but it does not necessarily start immediately.
C. When a thread stops running because of pre-emptive, it is placed at the front end of the runnable queue.
D. A thread may cease to be ready for a variety of reasons.
36、A member variable defined in a class can be accessed only by the classes in the same package. Which modifier should be used to obtain the access control A. private B. no modifier C. public D. protected
37、A public member vairable called MAX_LENGTH which is int type, the value of the variable remains constant value 100. Use a short statement to define the variable. A. public int MAX_LENGTH=100; B. final int MAX_LENGTH=100;
C. final public int MAX_LENGTH=100; D. public final int MAX_LENGTH=100.
38、Which expressions are correct to declare an array of 10 String objects
A. char str[]; B. char str[][]; C. String str[]; D. String str[10];
39、Which fragments are correct in Java source file A. package testpackage;
public class Test{//do something...} B. import java.io.*; package testpackage;
public class Test{// do something...}
C. import java.io.*;
class Person{// do something...} public class Test{// do something...} D. import java.io.*; import java.awt.*;
public class Test{// do something...}
40：
String s= \"hello\"; String t = \"hello\";
char c[] = {'h','e','l','l','o'} ; Which return true A. s.equals(t); B. t.equals(c); C. s==t;
D. t.equals(new String(\"hello\")); E. t==c.
41. Which of the following statements are legal A. long l = 4990; B. int i = 4L; C. float f = 1.1; D. double d = 34.4; E. double t = 0.9F.
42、
public class Parent { int change() {…} }
class Child extends Parent { }
Which methods can be added into class Child A. public int change(){} B. int chang(int i){} C. private int change(){} D. abstract int chang(){}
43、class Parent { String one, two;
public Parent(String a, String b){ one = a; two = b; }
public void print(){ System.out.println(one); } }
public class Child extends Parent { public Child(String a, String b){ super(a,b); }
public void print(){
System.out.println(one + \" to \" + two); }
public static void main(String arg[]){
Parent p = new Parent(\"south\ Parent t = new Child(\"east\ p.print(); t.print(); } }
Which of the following is correct A. Cause error during compilation. B. south east
C. south to north east to west
D. south to north east E. south east to west
44、Given the uncompleted method: 1)
2) { success = connect() 3} if (success==-1) {
4} throw new TimedOutException(); 5} } 6}}
TimedOutException is not a RuntimeException. Which can complete the method of declaration when added at line 1
A. public void method()
B. public void method() throws Exception
C. public void method() throws TimedOutException D. public void method() throw TimedOutException E. public throw TimedOutException void method()
45、Given the following code: 1) class Parent {
2} private String name; 3} public Parent(){} 4} }
5) public class Child extends Parent { 6} private String department; 7} public Child() {}
8} public String getValue(){ return name; } 9) public static void main(String arg[]) { 10} Parent p = new Parent(); 11} } 12) }
Which line will cause error A. line 3 B. line 6 C. line 7 D. line 8 E. line 10
46、The variable \"result\" is boolean. Which expressions are legal A. result = true;
B. if ( result ) { // do something... } C. if ( result!= 0 ) { // so something... } D. result = 1
47、Class Teacher and Student are subclass of class Person. Person p; Teacher t; Student s;
p, t and s are all non-null.
if(t instanceof Person) { s = (Student)t; } What is the result of this sentence A. It will construct a Student object. B. The expression is legal. C. It is illegal at compilation.
D. It is legal at compilation but possible illegal at runtime.
48、Given the following class: public class Sample{ long length;
public Sample(long l){ length = l; } public static void main(String arg[]){ Sample s1, s2, s3; s1 = new Sample(21L); s2 = new Sample(21L); s3 = s2;
long m = 21L; } }
Which expression returns true A. s1 == s2; B. s2 == s3; C. m == s1;
D. s1.equals(m).
49、Which classes can be used as the argument of the constructor of the class FilterInputStream A. FilterOutputStream B. File
C. InputStream
D. RandomAccessFile
50、Which classes can be used as the argument of the constructor of the class FileInputStream A. InputStream B. File
C. FileOutputStream D. String
51、Which is not a method of the class InputStream A. int read(byte[]) B. void flush() C. void close() D. int available()
52、Given the following code: class Person {
String name,department; public void printValue(){
System.out.println(\"name is \"+name);
System.out.println(\"department is \"+department); }
}
public class Teacher extends Person { int salary;
public void printValue(){
// doing the same as in the parent method printValue() // including print the value of name and department. System.out.println(\"salary is \"+salary); } }
Which expression can be added at the \"doing the same as...\" part of the method printValue() A. printValue(); B. this.printValue(); C. person.printValue(); D. super.printValue().
53. Which of the following assignment is not correct A. float f = 11.1;
B. double d = 5.3E12; C. double d = 3.14159; D. double d = 3.14D.
Linux基础
1. Linux文件权限一共10位长度，分成四段，第三段表示的内容是__。 A 文件类型 B 文件所有者的权限
C 文件所有者所在组的权限 D 其他用户的权限
2．在使用mkdir命令创建新的目录时，在其父目录不存在时先创建父目录的选项是__。 A -m B -d C -f D –p
3. 具有很多C语言的功能，又称过滤器的是 __ 。 A csh B tcsh C awk D sed
4. 下列文件中，包含了主机名到IP地址的映射关系的文件是： __ 。 A /etc/HOSTNAME B /etc/hosts C /etc/resolv.conf D /etc/networks
5. 命令可以从文本文件的每一行中截取指定内容的数据。__ A cp B dd C fmt D cut
6．对名为fido的文件用chmod 551 fido 进行了修改，则它的许可权是 __ 。
A -rwxr-xr-x B -rwxr--r-- C -r--r--r-- D -r-xr-x—x
7． 用ls –al 命令列出下面的文件列表， __ 文件是符号连接文件。 A -rw-rw-rw- 2 hel-s users 56 Sep 09 11:05 hello B -rwxrwxrwx 2 hel-s users 56 Sep 09 11:05 goodbey C drwxr--r-- 1 hel users 1024 Sep 10 08:10 zhang D lrwxr--r-- 1 hel users 2024 Sep 12 08:12 cheng