class Test {
 public int test(int a) {
  return a;
 }

 public String test(String a) {
  return a;
 }

 public float test(int a, String b) {
  return 0f;
 }

 public float test(String a, int b) {
  return 1.0f;
 }

 String test(float a) {
  return "";
 }

 String test(int a) {//该方法不是重载 
  return "";
 }
}

class A { 
 static int a = 1; 
 static int b = 2; 
 int c = 33;

 public static void printA() { 
  System.out.print(a); 
 } 

 public static void printB() { 
  System.out.print(b); 
 } 

}

class B extends A { 
 static int a = 3; 
 static int b = 4;
 int c = 44;

 public static void printB() { 
  System.out.print(b); 
 } 
}

public class Test { 
 public static void main(String[] args) { 
  B.printA();
  B.printB();
  System.out.print(B.a); 

  A a = new B();
  B b = new B();

  a.printB();
  b.printB();
  System.out.print(a.c);
  System.out.print(b.c);
 } 
} 

public class Animal {
 public void eat() {
  System.out.println("Animal eating...");
 }
}

public class Mammal extends Animal {
 public void eat() {
  System.out.println("Mammal eating...");
 }
}

public class Dog extends Mammal {
 public void eat() {
  System.out.println("Dog eating...");
 }
}

public interface Animal {
 void eat();
}

public class Mammal extends Animal {
 public void eat() {
  System.out.println("Mammal eating...");
 }
}

public class Dog extends Mammal {
 public void eat() {
  System.out.println("Dog eating...");
 }
}

public class Test { 
  /**
  * instanceof关键字检查代码
  */
 public static void main(String[] args) {
  Mammal m = new Mammal();
  Dog d = new Dog();
  System.out.print(m instanceof Animal);
  System.out.print(d instanceof Mammal);
  System.out.print(d instanceof Animal);
 }
}

public class Car{}

public class Speed{}

public class Benz extends Car{
 private Speed sp; 
}

class A {
 public String show(D obj) {
  return ("A and D");
 }

 public String show(A obj) {
  return ("A and A");
 }
}

class B extends A {
 public String show(B obj) {
  return ("B and B");
 }

 public String show(A obj) {
  return ("B and A");
 }
}

class C extends B {}

class D extends B {}

class Test {
 public static void main(String[] args) {
  A a1 = new A();
  A a2 = new B();
  B b = new B();
  C c = new C();
  D d = new D();
  System.out.println(a1.show(b)); // ①
  System.out.println(a1.show(c)); // ②
  System.out.println(a1.show(d)); // ③
  System.out.println(a2.show(b)); // ④
  System.out.println(a2.show(c)); // ⑤
  System.out.println(a2.show(d)); // ⑥
  System.out.println(b.show(b)); // ⑦
  System.out.println(b.show(c)); // ⑧
  System.out.println(b.show(d)); // ⑨
 }
}