单项选择题
class TestMain { static int x = 2; static { x = 4; } static public void main(String[] args) { int y = x + 1; System.out.println(y); } } 和命令行: java TestMain 结果为:()
A. 3 B. 5 C. 编译失败 D. 运行时异常被抛出
public class Employee{ private String name; public ...
public class Employee{ private String name; public Employee(String name){ this.name = name; } public void display(){ System.out.print(name); } } public class Manager extends Employee{ private String department; public Manager(String name,String department){ super(name); this.department = department; } public void display(){ System.out.println( super.display()+”,”+department); } } 执行语句new Manager(“smith”,”SALES”)后程序的输出是哪项?()
A. smith,SALES B. null,SALES C. smith,null D. null,null
public class Pet{ private String name; public Pet()...
public class Pet{ private String name; public Pet(){ System.out.print(1); } public Pet(String name){ System.out.print(2); } } public class Dog extends Pet{ public Dog(){ System.out.print(4); } public Dog(String name){ super(name); System.out.print(3); } } 执行new Dog(“棕熊”);后程序输出是哪项?()
A. 33 B. 13 C. 23 D. 123
public class Pet{ private String name; public Pet(){ System.out.print(1); } public Pet(String name){ System.out.print(2); } } public class Dog extends Pet{ public Dog(){ System.out.print(4); } public Dog(String name){ //这里隐藏了一句代码:super.pet(); this(); System.out.print(3); } } 执行new Dog(“棕熊”);后程序输出是哪项?()
A. 143 B. 423 C. 243 D. 1134