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JAVA题库:格林模拟试题三（上） |
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www.nanhushi.com 佚名 不详 |
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Questions
Question 1)
Which of the following are legal statements?
1) float f=1/3;
2) int i=1/3;
3) float f=1.01;
4) double d=999d;
Question 2)
Which of the following are Java keywords?
1) NULL
2) new
3) instanceOf
4) wend
Question 3)
Which of the following are valid statements?
1) System.out.println(1+1);
2) int i=2+’2’;
3) String s="on"+’one’;
4) byte b=255;
Question 4)
Which of the following statements are true?
1) The garbage collection algorithm in Java is vendor implemented
2) The size of primitives is platform dependent
3) The default type for a numerical literal with decimal component is a float.
4) You can modify the value in an Instance of the Integer class with the setValue method
Question 5)
Which of the following are true statements?
1) I/O in Java can only be performed using the Listener classes
2) The RandomAccessFile class allows you to move directly to any point a file.
3) The creation of a named instance of the File class creates a matching file in the underlying operating system only when the close method is called.
4) The characteristics of an instance of the File class such as the directory separator, depend on the current underlying operating system转贴于
Question 6)
Which of the following statements are true?
1) The instanceof operator can be used to determine if a reference is an instance of a class, but not an interface.
2) The instanceof operator can be used to determine if a reference is an instance of a particular primitive wrapper class
3) The instanceof operator will only determine if a reference is an instance of a class immediately above in the hierarchy but no further up the inheritance chain
4) The instanceof operator can be used to determine if one reference is of the same class as another reference thus
Question 7)
Which of the following statements are true?
1) An interface can only contain method and not variables
2) Interfaces cannot have constructors
3) A class may extend only one other class and implement only one interface
4) Interfaces are the Java approach to addressing its lack of multiple inheritance, but require implementing classes to create the functionality of the Interfaces.
Question 8)
Which of the following are valid statements
1) public class MyCalc extends Math
2) Math.max(s);
3) Math.round(9.99,1);
4)Math.mod(4,10);
Question 9)
Which of the following are methods of the Runnable interface
1) run
2) start
3) yield
4) stop转
Question 10)
Which of the following statements are true?
1) A byte can represent between -128 to 127
2) A byte can represent between -127 to 128
3) A byte can represent between -256 to 256
4) A char can represent between -2x2 pow 16 2 x2 pow 16 - 1
Question 11)
What will happen when you attempt to compile and run the following code
class Base{
public void Base(){
System.out.println("Base");
}
}
public class In extends Base{
public static void main(String argv[]){
In i=new In();
}
}
1) Compile time error Base is a keyword
2) Compilation and no output at runtime
3) Output of Base
4) Runtime error Base has no valid constructor
Question 12)
You have a public class called myclass with the main method defined as follows
public static void main(String parm[]){
System.out.println(parm[0]);
}
If you attempt to compile the class and run the program as follows
java myclass hello
What will happen?
1) Compile time error, main is not correctly defined
2) Run time error, main is not correctly defined
3) Compilation and output of java
4) Compilation and output of hello
Question 13)
Which of the following statements are true?
1) If a class has any abstract methods it must be declared abstract itself.
2) All methods in an abstract class must be declared as abstract
3) When applied to a class, the final modifier means it cannot be sub-classed
4) transient and volatile are Java modifiers
Question 14)
Which of the following are valid methods?
1) public static native void amethod(){}
2) public static void amethod(){}
3) private protected void amethod(){}
4) static native void amethod();
Question 15)
Which of the following statements are true?
1) Constructors cannot have a visibility modifier
2) Constructors can be marked public and protected, but not private
3) Constructors can only have a primitive return type
4) Constructors are not inherited
Question 16)
What will happen when you attempt to compile and run the following class?
class Base{
Base(int i){
System.out.println("Base");
}
}
class Severn extends Base{
public static void main(String argv[]){
Severn s = new Severn();
}
void Severn(){
System.out.println("Severn");
}
}
1) Compilation and output of the string "Severn" at runtime
2) Compile time error
3) Compilation and no output at runtime
4) Compilation and output of the string "Base"
Question 17)
Which of the following statements are true?
1) static methods do not have access to the implicit variable called this
2) A static method may be called without creating an instance of its class
3) A static method may not be overriden to be non-static
4) A static method may not be overloaded
Question 18)
Which of the following will compile without error?
1)
char c=’1’;
System.out.println(c>>1);
2)
Integer i=Integer("1");
System.out.println(i>>1);
3)
int i=1;
System.out.println(i<<<1);
4)
int i=1;
System.out.println(i<<1);
Question 19)
Which of the following are true?
1) A component may have only one event listener attached at a time
2) An event listener may be removed from a component
3) The ActionListener interface has no corresponding Adapter class
4) The processing of an event listener requires a try/catch block
Question 20)
Which of the following are Java keywords?
1) sizeof
2) main
3) transient
4) volatile
Question 21)
Which of the following statements are true?
1) The default constructor has a return type of void
2) The default constructor takes a parameter of void
3) The default constructor takes no parameters
4) The default constructor is not created if the class has any constructors of its own.
Question 22)
Which of the following statements are true?
1) All of the variables in an interface are implicitly static
2) All of the variables in an interface are implicitly final
3) All of the methods in an interface are implicitly abstract
4) A method in an interface can access class level variables
Question 23)
Which of the following statements are true?
1) The String class is implemented as a char array, elements are addressed using the stringname[] convention
2) The + operator is overloaded for concatenation for the String class
3) Strings are a primitive type in Java and the StringBuffer is used as the matching wrapper type
4) The size of a string can be retrieved using the length property
Question 24)
Which of the following statements are true?
1) A method in an interface must not have a body
2) A class may extend one other class plus at most one interface
3) A class may extends at most one other class plus implement many interfaces
4) An class accesses an interface via the keyword uses
Question 25)
Which of the following statements are true?
1) The following statement will produce a result of 1. System.out.println( -1 >>>2);
2) Performing an unsigned left shift (<<<) on a negative number will always produce a negative number result
3) The following statement will produce a result of zero, System.out.println(1 >>1);
4) All the Java integral types are signed numbers
Question 26)
Which of the following statements are true?
1) The elements in a Java array can only be of primitive types, not objects
2) Arrays elements are initialized to default values wherever they are created using the keword new
3) An array may be dynamically resized using the setSize method
4) You can find out the size of an array using the size method
Question 27)
Given the following class
public class Ombersley{
public static void main(String argv[]){
boolean b1 = true;
if((b1 ==true) || place(true)){
System.out.println("Hello Crowle");
}
}
public static boolean place(boolean location){
if(location==true){
System.out.println("Borcetshire");
}
System.out.println("Powick");
return true;
}
}
What will happen when you attempt to compile and run it?
1) Compile time error
2) Output of "Hello Crowle"
3) Output of Borcetshire and Powick followed by "Hello Crowle"
4) No output
Question 28)
You are given a class hierarchy with an instance of the class Dog. The class Dog is a child of mammal and the class Mammal is a child of the class Vertebrate. The class Vertebrate has a method called move which prints out the string "move". The class mammal overrides this method and prints out the string "walks". The class Dog overrides this method and prints out the string "walks on paws". Given an instance of the class Dog,. how can you access the ancestor method move in Vertebrate so it prints out the string "move";
1) d.super().super().move();
2) d.parent().parent().move();
3) d.move();
4) none of the above;
Question 29)
Which of the following most closely describes the process of overriding?
1) A class with the same name replaces the functionality of a class defined earlier in the hierarchy
2) A method with the same name completely replaces the functionality of a method earlier in the hierarchy
3) A method with the same name but different parameters gives multiple uses for the same method name
4) A class is prevented from accessing methods in its immediate ancestor
Question 30)
Which of the following statements are true?
1) The % is used to calculate a percentage thus: 10 % 20=50
2) The / operator is used to divide one value by another
3) The # symbol may not be used as the first character of a variable
4) The $ symbol may not be used as the first character of a variable
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