class C1 {}

class C2 extends C1 { }

class C3 extends C2 { }

class C4 extends C1 {}

C1 c1 = new C1();

C2 c2 = new C2();

C3 c3 = new C3();

C4 c4 = new C4();

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());
}
}

public class Test {
public static void main(String[] args) {
new B();
}
}

class A {
int i = 7;

public A() {
setI(20);
System.out.println("i from A is " + i);
}

public void setI(int i) {
this.i = 2 * i;
}
}

class B extends A {
public B() {
// System.out.println("i from B is " + i);
}

@Override
public void setI(int i) {
this.i = 3 * i;
}
}

class A {
public A() {
System.out.println("The default constructor of A is invoked");
}
}

class B extends A {
public B() {
System.out.println("The default constructor of B is invoked");
}
}

public class C {
public static void main(String[] args) {
B b = new B();
}
}

class Employee;

class Manager extends Employee;

class Director extends Employee;
则以下语句哪个能通过编译？ ( )。

abstract class Shape{
int x;
int y;
public abstract void draw();
}

class Employee{}
class Manager extends Employee{}
class Director extends Employee{}

则下列语句通过编译的有哪些？（ ）

class A {
double f(double x, double y) {
return x * y;
}
}

class B extends A {
double f(double x, double y) {
return x + y;
}
}

public class Test {
public static void main(String args[]) {
A obj = new B();
System.out.println(obj.f(4, 6));
}
}

class father {

 public int addvalue(int a, int b) {

  int s = a + b;

  return s;

 }

}

class child extends father {

}

class A {

 int v1 = 10;

 int v2 = 10;

 public A() {

 }

 public void m1() {

  System.out.println("A m1");

 }

 public void m2() {

  System.out.println("A m2");

 }

}

class B extends A {

 int v2 = 20;

 int v3 = 20;

 public B() {

 }

 public void m2() {

  System.out.println("B m2");

 }

 public void m3() {

  System.out.println("B m3");

 }

}

public class Main {

 public static void main(String[] args) {

  B b = new B();

  b.m1();

  b.m2();

  b.m3();

  System.out.println(b.v1);

  System.out.println(b.v2);

  System.out.println(b.v3);

 }

}

class Base {
static void test() {
System.out.println("Base.test()");
}
}

class Child extends Base {
static void test() {
System.out.println("Child.test()");
Base.test(); // Call the parent method
}
}

public class Main {
public static void main(String[] a) {
Child.test();
}
}

class Father {
int a = 100;
int b = 200;

public void print() {
System.out.println(a + " " + b);
}
}

class Child extends Father {
int b = 300;
int c = 400;

public void print() {
System.out.println(a + " " + b + " " + c);
}

public void printExtend() {
System.out.println(c);
}

}

public class Main {
public static void main(String[] a) {
Father obj=new Child();
System.out.println(obj.a+" "+obj.b);
obj.print();
}
}

class Father {
int a =100;
public void print() {
System.out.println(a);
}
}
class Child1 extends Father {
int a =200;
public void print() {
System.out.println(a);
}
}
class Child2 extends Father {
int a =300;
public void print() {
System.out.println(a);
}
}
public class Main {
public static void main(String[] a) {
Father obj1;
obj1=new Child1();
System.out.println(obj1.a);
obj1.print();

obj1=new Child2();
System.out.println(obj1.a);
obj1.print();
}
}

abstract class Person {
public abstract void eat();
}
public class Main {
public static void main(String[] a) {

Person p = new Person() {
public void eat() {
System.out.println("eat something");
}
};
p.eat();
}
}