阿里巴巴技术类笔试题
1. 1 byte
2. 1024 bytes
3. 512 bytes
4. 4096 bytes
5. 1024 bits
Question 46. (多选)
已知如下类定义：
class Base {
public Base (){ //… }
public Base ( int m ){ //… }
protected void fun( int n ){ //… }
}
public class Child extends Base{
// member methods
}
如下哪句可以正确地加入子类中?
1. private?void?fun(?int?n?){?//…}
2. void fun ( int n ){ //… }
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3. protected void fun ( int n ) { //… }
4. public void fun ( int n ) { //… }
Question 47. (单选)
It is an important feature of the Java language that it always provides a default constructor to a class.
1. FALSE
2. TRUE
Question 48. (单选)
A class contained in Java program file must have the same name as the file, except for the extension “.java”.
1. FALSE
2. TRUE
Question 49. (单选)
Each method in a class must have a unique name.
1. FALSE
2. TRUE
Question 50. (单选)
When an instance of a class, or object, is specified as a parameter to a method, a reference to the said object is passed to the method.
1. FALSE
2. TRUE
Question 51. (单选)
All interface methods must be declared as public when implemented in a class.
1. FALSE
2. TRUE
Question 52. (单选)
Which of the following expressions will produce errors upon compilation?
(A) boolean a = (boolean) 1;
(B) boolean b = (false && true);
(C) float y = 22.3; (D) int x = (25 | 125)
1. (A) & (C)
2. (A)
3. (A), (C) & (D)
4. (A), (B) & (D)
Question 53. (单选)
Which lines of the following will produce an error?
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1. byte a1 = 2, a2 = 4, a3;
2. short s = 16;
3. a2 = s;
4. a3 = a1 * a2;
1. Line 3 and Line 4
2. Line 1 only
3. Line 3 only
4. Line 4 only
5. Line 1 and Line 4
Question 54. (单选)
Which keyword can protect a class in a package from accessibility by the classes outside the package?
1. don’t use any keyword at all (make it default)
2. private
3. protected
4. final
Question 55. (单选)
Which of the following statements are valid array declaration?
(A) int number();
(B) float average[];
(C) double[] marks;
(D) counter int[];
1. (B) & (C)
2. (A)
3. (A) & (C)
4. (D)