public class Child extends People { People father; public Child(Stri

1.下列程序执行结果是：（） class People { String name; public People() { System.out.print(1); } public People(String name) { System.out.print(2); this.name = name; }}public class Child extends People { People father; public Child(String name) { System.out.print(3); this.name = name; father = new People(name + ":F"); } public Child() { System.out.print(4); } public static void main(String[] args) { new Child("Alice"); } }选项： A:32; B:132; C:123; D:1234

2.被顺序调用, 请选择输出结果 ( )class People { String name; public People() { System.out.print(1); } public People(String name) { System.out.print(2); this.name = name; } } class Child extends People { People father; public Child(String name) { System.out.print(3); this.name = name; father = new People(name + ":F"); } public Child(){ System.out.print(4); } }public class Test{ public static void main(String[] args){ People p = new Child("梅西"); }} 选项：312|32|432|132

3. 下面是People和Child类的定义和构造方法,每个构造方法都输出编号。在执行new Child("mike")的时候都有哪些构造方法被顺序调用?请选择输出结果 ( )Class People { String name; public People() { System.out.print(1); } public People(String name) { System.out.print(2); this.name = name; }}Class Child extends People { People father; public Child(String name) { System.out.print(3); this.name = name; father = new People(name + ":F"); } public Child(){ System.out.print(4); }} 选项： A:312 B: 32 C: 432 D: 132

4.下面是People和Child类的定义和构造方法,每个构造方法都输出编号。在执行new Child("mike")的时候都有哪些构造方法被顺序调用?请选择输出结果 ( )Class People { String name; public People() { System.out.print(1); } public People(String name) { System.out.print(2); this.name = name; }}Class Child extends People { People father; public Child(String name) { System.out.print(3); this.name = name; father = new People(name + ":F"); } public Child(){ System.out.print(4); }}(2分) 选项： A:312 B:32 C:432 D:132

5.下面是People和Child类的定义和构造方法，每个构造方法都输出编号。在执行new Child("mike")的时候都有哪些构造方法被顺序调用？请选择输出结果 ( )Class People { String name; public People() { System.out.print(1); } public People(String namE、 { System.out.print(2); this.name = name; }}Class Child extends People { People father; public Child(String namE、 { System.out.print(3); this.name = name; father = new People(name + ":F"); } public Child() { System.out.print(4); }} 选项： A:312 B:32 C:432 D:132

6.阅读下面的程序，分析代码是否能够编译通过，如果能编译通过，请列出运行的结果。否则请说明编译失败的原因。public class Demo {public static void main(String[] args) {String name=new Father("tom"){}.getName();System.out.println(name);}}class Father {private String name;public String getName() {return name;}public void setName(String name) {this.name = name;}public Father(String name) {this.name = name;}}

7.class Student{ private String name; public Student(String name) { this.name=name; } public void setName(String name) { this.name=name; } public String getName() { return name; }}public class test4 { public static void modifyStudent(Student std) { std.setName("张三"); } public static void main(String[] args) { Student s1=new Student("李四"); System.out.println(s1.getName()); modifyStudent(s1); System.out.println(s1.getName()); }}

8.已知People类定义如下： public class People{ String name; int age; char sex; People(String n,int a,char s) { name=n; age=a; sex=s; } } MainClass类定义如下： public class MainClass{ public static void main(String args[]) { People p1=new People("lily",20,'女'); People p2=p1; People p3=new People("lily",20,'女'); System.out.print((p1==p2)+","+(p1==p3)); } } 程序的输出结果是________________________________.

9. 已知People类定义如下： public class People{ String name; int age; char sex; People(String n,int a,char s) { name=n; age=a; sex=s; } } MainClass类定义如下： public class MainClass{ public static void main(String args[]) { People p1=new People("lily",20,'女'); People p2=p1; People p3=new People("lily",20,'女'); System.out.print((p1==p2)+","+(p1==p3)); } }程序的输出结果是________________________________.

10.以下程序的输出结果是？class Person{String name="person";public void shout(){System.out.print(name);}}class Student extends Person{String name="student";String school="school";}class Test{public static void main(String[] args){Person p=new Student();System.out.print(p instanceof Student);System.out.print(p instanceof Person);System.out.print(p instanceof Object);System.out.print(p instanceof System);}}

11.以下代码运行输出是（）public class Person{private String name=”Person”;int age=0;}public class Child extends Person{public String grade;public static void main(String[] args){Person p = new Child();System.out.println(p.name);}}选项： A:输出：Person; B:没有输出; C:编译出错; D:运行出错

12.编译运行如下java代码，输出结果是（） class Person{ String name = "person"; public void shout(){ System.out.print(name); } } class Student extends Person{ String name = "student"; String school = "school"; } public class Test{ public static void main(String[] args){ Person p = new Student(); p.shout(); } } 选项： A、person B、student C、person student D、编译错误

13.编译运行如下 Java代码，输出结果是。class Base {public void method(){System.out.print ("Base method");}}class Child extends Base{public void methodB(){System.out.print ("Child methodB");}}class Sample {public static void main(String[] args) {Base base= new Child();base.methodB();}}

14.public class InheritThread extends Thread {private String name;public InheritThread (String name) {this.name = name;}public void run() {System.out.println("Greetings from thread name !");}}public static void main(String args[]){InheritThread greetings = new InheritThread ("Inherited");greetings.start();System.out.println(" Main Thread has been ended");}以上代码执行的结果可能是：

15.【填空题】23. import java.text.*; public class Java_2 { public static void main(String[] args) { Person[] people = new Person[2]; people[0] = new Worker("老张", 30000); people[1] = new Student("小王", "计算机科学"); for (int i = 0; i < people.length; i++) { Person p = people[i]; //*********Found********** System.out.println(____________________() + ", " + p.getDescription()); } } } //*********Found********** ________________ class Person { public Person(String n) { name = n; } //*********Found********** public ___________________ String getDescription(); public String getName() { return name; } private String name; } //*********Found********** class Worker _________________ Person { public Worker(String n, double s) { super(n); salary = s; } public String getDescription() { NumberFormat formatter = NumberFormat.getCurrencyInstance(); return "工人，年薪是 " + formatter.format(salary) + "。"; } private double salary; } //*********Found********** class Student _________________ Person { public Student(String n, String m) { super(n); major = m; } public String getDescription() { return "学生，专业是 " + major + "。"; } private String major; }

16.阅读下列的程序import java.util.*;class Student { String name; String age; public Student(String name, String age) { this.name = name; this.age = age; } public String toString() { return name + ":" + age; }}public class Example{ public static void main(String[] args) { Set set = new HashSet(); set.add(new Student("Tom", "10")); set.add(new Student("Jerry", "10")); set.add(new Student("Tom", "10")); }}下列选项中，程序的运行结果是（）选项： A:2; B:3; C:1; D:不固定个数

17. 编译运行如下Java代码,输出结果是( )class Base {public void method(){System.out.print ("Base method");}}class Child extends Base{public void methodB(){System.out.print ("Child methodB");}}class Sample {public static void main(String[] args) {Base base= new Child();base.methodB();}} 选项： A、 Base method B、 Child methodB C、 Base method Child MethodB D、编译错误

18.阅读下列的程序import java.util.*;class Student { String name; String age; public Student(String name, String age) { this.name = name; this.age = age; } public String toString() { return name + ":" + age; }}public class Example{ public static void main(String[] args) { Set set = new HashSet(); set.add(new Student("Tom", "10")); set.add(new Student("Jerry", "10")); set.add(new Student("Tom", "10")); }}下列选项中，程序的运行结果是：set集合中的元素个数为（）选项： A:1 B:不固定个数 C:3 D:2

19.填写代码将下列程序补充完整。 enum OperatingSystem { android, ios, Windows }; abstract class a { private string name; public string Name { get { return name; } set { name = value; } } public （1） string ToString(); } class b : a { private string name; private OperatingSystem os; public b(string name, OperatingSystem os):base(name) { this.name = name; this.os = os; } public override string ToString() { return this.Name + "游戏，运行系统" + this.os + "。"; } }

20.阅读下列的程序import java.util.*;class Student { String name; String age; public Student(String name, String age) { this.name = name; this.age = age; } public String toString() { return name + ":" + age; }}public class Example{ public static void main(String[] args) { Set set = new HashSet(); set.add(new Student("Tom", "10")); set.add(new Student("Jerry", "10")); set.add(new Student("Tom", "10")); }}下列选项中，程序的运行结果是：set集合中的元素个数为（）选项： A:2 B:3 C:1 D:不固定个数

21.以下程序的调试结果为? public class Outer{ public String name = "Outer"; public static void main(String argv[]){ Inner i = new Inner(); i.showName(); } private class Inner{ String name =new String("Inner"); void showName(){ System.out.println(name); } } }

22.private String name; public Student(){ name = "Unknown"; } public void setName (String n){ name = n; } public String getName(){ return name; }}class Cl1{ public static void main(String[] args){ Student a = new Student(); System.out.println(a.getName()); a.setName("xyz"); String b = a.getName(); System.out.println(b); }}输出是Unknownxyz选项： A:正确; B:错误