阅读下面程序补全程序代码，并给出输出结果。(备注⑤⑥空格不能填相同代码)import java.util.*;class Cage<E> e

lionCage = ① ;Cage butterflyCage = ② ;lionCage.add(new ③ );butterflyCage.add(new ④ );t.feedAnimals( ⑤ );t.feedAnimals( ⑥ );}void feedAnimals(Cage someCage) { for (Animal a:someCage) a.feedMe();}}输出结果为： ⑦ 。">1.阅读下面程序补全程序代码，并给出输出结果。(备注⑤⑥空格不能填相同代码)import java.util.*;class Cage extends LinkedList{}; class Animal{ public void feedMe(){ };} class Lion extends Animal{public void feedMe(){System.out.println("Feeding lions");}}class ButterFly extends Animal{public void feedMe(){System.out.println("Feeding butterflies");}}public class WildcardTest{public static void main(String args[]){WildcardTest t = new WildcardTest();Cage lionCage = ① ;Cage butterflyCage = ② ;lionCage.add(new ③ );butterflyCage.add(new ④ );t.feedAnimals( ⑤ );t.feedAnimals( ⑥ );}void feedAnimals(Cage someCage) { for (Animal a:someCage) a.feedMe();}}输出结果为： ⑦ 。

lionCage = ;Cage butterflyCage = ② ;lionCage.add(new );butterflyCage.add(new );t.feedAnimals( lionCage );t.feedAnimals(butterflyCage );}void feedAnimals(Cage someCage) { for (Animal a:someCage) a.feedMe();}}">2.阅读下面程序补全程序代码，并给出输出结果。(备注⑤⑥空格不能填相同代码)import java.util.*;class Cage extends LinkedList{}; class Animal{ public void feedMe(){ };} class Lion extends Animal{public void feedMe(){System.out.println("Feeding lions");}}class ButterFly extends Animal{public void feedMe(){System.out.println("Feeding butterflies");}}public class WildcardTest{public static void main(String args[]){WildcardTest t = new WildcardTest();Cage lionCage = ;Cage butterflyCage = ② ;lionCage.add(new );butterflyCage.add(new );t.feedAnimals( lionCage );t.feedAnimals(butterflyCage );}void feedAnimals(Cage someCage) { for (Animal a:someCage) a.feedMe();}}

lionCage = ;Cage butterflyCage = ;lionCage.add(new ③ );butterflyCage.add(new );t.feedAnimals( lionCage );t.feedAnimals(butterflyCage );}void feedAnimals(Cage someCage) { for (Animal a:someCage) a.feedMe();}}">3.阅读下面程序补全程序代码，并给出输出结果。(备注⑤⑥空格不能填相同代码)import java.util.*;class Cage extends LinkedList{}; class Animal{ public void feedMe(){ };} class Lion extends Animal{public void feedMe(){System.out.println("Feeding lions");}}class ButterFly extends Animal{public void feedMe(){System.out.println("Feeding butterflies");}}public class WildcardTest{public static void main(String args[]){WildcardTest t = new WildcardTest();Cage lionCage = ;Cage butterflyCage = ;lionCage.add(new ③ );butterflyCage.add(new );t.feedAnimals( lionCage );t.feedAnimals(butterflyCage );}void feedAnimals(Cage someCage) { for (Animal a:someCage) a.feedMe();}}

4.public abstract class Animal { public abstract void eat();}public class Cat extends Animal{ public void 【代码1】(){ System.out.println("猫吃猫粮"); }}public class Test { public static void main(String[] args) { Animal a = new 【代码2】(); a.eat(); }}

5. 下列程序的运行结果是__________。class Animal{ public Animal(){ System.out.println("Animal"); }}class Dog extends Animal{ public Dog(){ System.out.println("Dog"); }}public class Test{ public static void main(String[] args){ Animal d = new Dog(); }}

6.下面程序运行结果为 class Animal{ public Animal(){ System.out.println("Animal"); }}public class Bird extends Animal{ public Bird(){ System.out.println("Bird"); } public static void main(String[]args){ Bird b = new Bird(); }}选项： A:Animal; B:Bird; C:AnimalBird; D:BirdAnimal

7.下列代码的运行结果是（） public class Animal{ public String noise(){ return “peep”; } public static void main(String[] args){ Animal animal = new Dog(); Cat cat = (Cat)animal; System.out.println(cat.noise()); } } class Dog extends Animal{ public String noise(){ return “bark”; } } class Cat extends Animal{ public String noise(){ return “meow”; } }

8.【填空题】阅读下面的程序，在不new Cat类的情况下,添加代码运行Demo的mian方法后执行Cat的eat()方法。 public class Demo { public static void main(String[] args) { Animal animal = new Cat(); ________； cat.eat(); } } class Animal{ public void eat(){ System.out.println("animal eat"); } } class Cat extends Animal{ public void eat(){ System.out.println("cat eat"); } }

9.下面程序运行结果为class Animal{public Animal(){ System.out.println("Animal");}}// Bird类是Animal的子类public class Bird extends Animal{public Bird(){ System.out.println("Bird");}public static void main(Stringargs){ Bird b = new Bird();}} 选项： A、Animal B、Bird C、AnimalBird D、BirdAnimal

10.下面程序在控制台输出的内容：（）class Creature extends java.lang.Object { public Creature() { System.out.println("-Creature-"); }}class Animal extends Creature { public Animal() { System.out.println("-Animal-"); }}class Wolf extends Animal { public Wolf() { System.out.println("-Wolf-"); }}public class ConStructorCallTest { public static void main(String[] args) { new Wolf(); }}选项： A:-Wolf-; B:-Creature--Animal--Wolf-; C:控制台没有任何输出。; D:编译出错，程序不能运行！

11.下列ABCD注释标注的哪行代码有错误?public interface Com { abstract void cry(); //A public int x = 0; //B }abstract class Animal implements Com {}class Dog extends Animal { void cry() //C { System.out.println("wangwang"); }}class E { public static void main(String args[]){ Com com = new Dog() ; //D com.cry(); }}

12.下面程序的运行结果是（）。class Animal{ public Animal(){ System.out.println("I'm an animal."); }}class Bird extends Animal{ public Bird(){ System.out.println("I'm a bird."); }}public class AnimalTest{ public static void main(String[] args) { Bird b = new Bird(); }}选项： A:编译错误; B:无输出结果; C:I'm a bird.; D:I'm an animal.I'm a bird.

13.阅读下列程序，并给出程序运行的结果。Public class PolymorphismDemo {Public static void main(String] args) { m(new GraduateStudent()); m(new Student()); m(new Person());} Public static void m(Object x) {System.out.println(x.toString());}} Class GraduateStudent extends Student {} Class Student extends Person {Public String toString() { return "I am a student";}} Class Person extends Object {Public String toString() { return "I am a person";}}

14.下面代码的输出结果是。 interface Animal1{ public default void eat () { System.out.println ("I can eat anything. ") ;} public static void speak () { System.out.println ("I can speak English. ") ;} } interface Person extends Animal1{ public default void work () { System.out.println ("I can working. ") ; } } class Student implements Person{ String major; public Student () {} } public class InterfaceTest{ public static void main (String [] args) { Student s=new Student () ; s.eat () ; Animal1.speak () ; s.work () ; } }

15.有以下类定义,运行后abstract class Animal{ abstract void say();}public class Cat extends Animal{ public Cat(){ System.out.printf("I am a cat"); } public static void main(String[] args) { Cat cat=new Cat(); }}选项： A:I am a cat; B:Animal能编译，Cat不能编译; C:Animal不能编译，Cat能编译; D:编译能通过，但是没有输出结果

16.找出下面代码中存在的错误。public class Test { public static void main(String[] args) { m(new GraduateStudent()); m(new Student()); m(new Person()); m(new Object()); } public static void m(Student x) { System.out.println(x.toString()); }}class GraduateStudent extends Student {}class Student extends Person { @Override public String toString() { return "Student"; }}class Person extends Object { @Override public String toString() { return "Person"; }}

17.请写出程序运行的结果。class Animal{ int m=100; public int seeM() { return m; } public int getM() { return m; }}class Dog extends Animal{ int m=6; public int seeM() { return m; }}public class E {public static void main(String[] args) { Animal a = null; Dog d = new Dog(); a = d; System.out.printf("%d:%d:%d", d.seeM(),a.seeM(),a.getM());}}

18.class First{public First(){aMethod(); } public void aMethod(){System.out.println(“in First class”);} } public class Second extends First{ public void aMethod(){System.out.println(“in Second class”);}public static void main(String[ ] args){new Second( ); } }选项： A:in First class B:in Second class C:无输出 D:in First classin Second class

19.阅读下面的程序，分析代码是否能编译通过，如果能编译通过，请列出运行的结果。如果不能编译通过，请说明原因。代码一：Class RunHandler { public void run(){ System.out.println("run");}}Public class Test { public static void main(String ] args) { Thread t = new Thread(new RunHandler()); t.start();}}2代码二：Public class A extends Thread{ protected void run() { System.out.println("this is run()"); } public static void main(String] args) { A a = new A(); a .start(); }}3代码三：Public class Test{ private Object obj=new Object(); public synchronized void a(){ try { obj.wait(); System.out.println("waiting"); } catch (InterruptedException e) { System.out.println("Exception"); } } public static void main(String] args) { new Test().a(); }}4为了使下面的程序能够输出“Thread is running”，请在在空格处填上相应的代码。Public class B implements Runnable { public static void main(String] args) { Thread t = new Thread(new B()); ( )( )( )_____ //此处填空 } public void run() { System.out.println("Thread is running"); } public void go() { start(1); } public void start(int i) { }}

20.阅读下面的程序，并写出运行的结果 class Vehicle { public void drive() { System.out.println("Vehicle: drive"); } } class Car extends Vehicle { public void drive() { System.out.println("Car: drive"); } } public class Test { public static void main (String args []) { Vehicle v= new Vehicle(); Vehicle c = new Car(); v.drive(); c.drive(); } }

21.对于static函数，子类加了相同的函数，输出是？class M { public static void output() { System.out.println("M"); }}class N extends M { public static void output() { System.out.println("N"); }}public class StaticTest { public static void main(String[] args) { M m = new N(); m.output(); }

22.根据以下程序可以判断选项（）没有语法错误。public class Person{ public Person(int id, String name)throws Exception{}}class MyException extends Exception{}选项： A:public class Test{public static void main(String[] args){System.out.println(new Person(20, “John”));}} B:public class Test{public static void main(String[] args){System.out.println(new Person(20, “John”).toString());}} C:public class Test{public static void main(String[] args)throws Exception{System.out.println(new Person(20, “John”).toString());}} D:public class Test{public static void main(String[] args)throws MyException{System.out.println(new Person(20, “John”).toString());}}

23. class A{ A( ){ System.out.print(10); }}public class Demo extends A { Demo(){ System.out.println(20); } public static void main(String[] args) { A a=new A( ); Demo d=new Demo( ); }}