阿里巴巴面试题.docxVIP

阿里巴巴面试题 阿里巴巴面试题 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 ){ //... } 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 a Java program file must have the same name as the file, except for the extension 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) 3. (A), (C) (D) 4. (A), (B) (D) Which lines of the following will produce an error? 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. dont 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