以下代码，查找编译错误。public class Test { public static void main(String[] args

1.以下代码，查找编译错误。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"; }}选项： A:m(new GraduateStudent()) 有错; B:m(new Student())有错; C:m(new Person()) 有错; D:m(new Object())有错

2.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"; }} 选项：A、m(new GraduateStudent()),产生错误 B、m(new Student()) ,产生错误 C、m(new Person()) ,产生错误 D、m(new Object()) ,产生错误

3.关于如下代码，下列选项正确的是（）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 { public String toString() { return "Student"; } } class Person extends Object { public String toString() { return "Person"; } }选项： A:m(new GraduateStudent()); 引起错误; B:m(new Person()) ;引起错误; C:m(new Object()); 引起错误; D:m(new Student()) ;引起错误

4.分析下列代码，找出编译错误。 public class Test { public static void main(String[ ] args) { m(new GraduateStudent()); m(new Student()); m(new Person()); } public static void m(Student x) { System.out.println(x.toString()); } } class GraduateStudent extends Student { } class Student extends Person { public String toString() { return "Student"; } } class Person extends Object { public String toString() { return "Person"; } } 选项： A、m(new Student()) 会导致编译错误 B、m(new Person()) 会导致编译错误 C、以下都不对 D、m(new GraduateStudent()) 会导致编译错误

5.public class DynamicBindingDemo { public static void main(String[] args) { Object o = new GraduateStudent(); Object o1 = new Object(); if (o1 instanceof GraduateStudent) { System.out.println("Never got here"); GraduateStudent gs = (GraduateStudent)o1; } m(o); m(new Student()); m(new Person()); m(new Object()); } public static void m( 【1】 ) { System.out.println(x.toString()); }} class GraduateStudent extends Student {}class Student extends Person { public String toString() { return "Student"; }}class Person extends Object { public String toString() { return "Person"; }}

6.分析下列代码，找出编译错误（本题为多选） 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 { public String toString() { return "Student"; } } class Person extends Object { public String toString() { return "Person"; } } 选项： A、m(new Object()) 会导致编译错误 B、m(new Student()) 会导致编译错误 C、m(new GraduateStudent()) 会导致编译错误 D、m(new Person()) 会导致编译错误

7.下面代码的运行结果是（）Public class Test { public static void main(String] args) { new Person().printPerson(); new Student().printPerson(); }}Class Student extends Person { @Override public String getInfo() { return "Student"; }}Class Person { public String getInfo() { return "Person"; } public void printPerson() { System.out.println(getInfo()); }} 选项： A: Person Person B: Person Student C: Stduent Student D: Student Person

8. 单选题What is the output of the following code? ( )Public class Test {Public static void main(String] args) {New Person().printPerson();New Student().printPerson();}}Class Student extends Person {@OverridePublic String getInfo() {Return "Student";}}Class Person {Public String getInfo() {Return "Person";}Public void printPerson() {System.out.println(getInfo());}} 选项： A:Person Person B:Person Student C:Stduent Student D:Student Person

9.下列代码的输出是什么public class Test { public static void main(String[] args) { new Person().printPerson(); new Student().printPerson(); }} class Student extends Person { private String getInfo() { return "Student"; }} class Person { private String getInfo() { return "Person"; } public void printPerson() { System.out.println(getInfo()); }}选项： A:Person Person; B:Person Student; C:Stduent Student; D:Student Person

10.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

11.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

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

(s); } }public class Person{ public int ID { get; set; } public string Name { get; set; } public static void PromptName(T t) where T : Person { Console.WriteLine(t); } }程序运行结果">13.阅读下面程序段class Student : Person{ public override string ToString() { return ID + "\t" + Name; } static void Main() { Student s = new Student(); s.ID = 1; s.Name = "JSON"; PromptName(s); } }public class Person{ public int ID { get; set; } public string Name { get; set; } public static void PromptName(T t) where T : Person { Console.WriteLine(t); } }程序运行结果

14.请写出下面程序的输出结果。class Person { 　　 public void m() { System.out.println(“I am in Person.”); } 　 } 　 public class Teacher extends Person { 　　 public void m() { System.out.println(“I am in Teacher.”); } 　　 public static void main(String args[]){ 　　 Person t = new Teacher(); 　 t.m(); 　　 }}

15.定义类间关系如下，对象定义实例化正确的是（）。 public class Person{ }public class Student extends Person{ }public class Worker extends Person{ }选项： A:Person p1 = new Person(); B:Person p2 = new Student(); C:Student p3 = new Student(); D:Student p4 = new Person();

16.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);}}

17.【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; }

(s); } }public class Person{ public int ID { get; set; } public string Name { get; set; } public static void PromptName(T t) where T : Person { Console.WriteLine(t); } }程序运行结果：选项： A:1 JSON; B:Student; C:Person; D:出错，约束条件受限">18.阅读下面程序段class Student : Person{ public override string ToString() { return ID + "\t" + Name; } static void Main() { Student s = new Student(); s.ID = 1; s.Name = "JSON"; PromptName(s); } }public class Person{ public int ID { get; set; } public string Name { get; set; } public static void PromptName(T t) where T : Person { Console.WriteLine(t); } }程序运行结果：选项： A:1 JSON; B:Student; C:Person; D:出错，约束条件受限

19.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(); }

20. 下列代码的输出结果是（）class Father{int m=100;public int setM(){return m;}}class Son extends Father{int m=6;public int setM(){return m;}}public class E{public static void main(String args[]){Sonobj=new Son();System.out.println(son.setM());}}

21.方法 getValue() 用以下两种方式进行覆盖. 那种正确?I:public class Test { public static void main(String[] args) { A a = new A(); System.out.println(a.getValue()); }} class B { public String getValue() { return "Any object"; }} class A extends B { public Object getValue() { return "A string"; }} II:public class Test { public static void main(String[] args) { A a = new A(); System.out.println(a.getValue()); }} class B { public Object getValue() { return "Any object"; }} class A extends B { public String getValue() { return "A string"; }}选项： A:I; B:II; C:I 和 II都可以; D:都不行

22.下列JAVA代码中Test类中的4个输出语句的输出结果依次是（）。 Class person { String name = “person”; Public void shout() { System.out.println(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); true false true false false true false true true true true 编译错误 true true false 编译错误