java方法重载--参数类型转换

package com.xiuye.test;

import java.io.Serializable;

public class TestOverload {

static abstract class A {

}

static class B extends A {

}

static class C extends A {

}

public void f(A a) {
System.out.println("AAAAAAA");
}

public void f(B a) {
System.out.println("BBBBBBB");
}

public void f(C a) {
System.out.println("CCCCCCC");
}

public static void main(String[] args) {
TestOverload l = new TestOverload();
// l.f(new A());
l.f(new B());
l.f(new C());

say('a');

}

/**
* 依次注释1~9， say('a')会依次向上转型输出，
* char->int->long->float->double->Character->Serializable->Object->char...
*
* @param obj
*/

// 8
public static void say(Object obj) {
System.out.println("Object");
}

// 1
public static void say(char obj) {
System.out.println("char");
}

// 2
public static void say(int obj) {
System.out.println("int");
}

// 3
public static void say(long obj) {
System.out.println("long");
}

// 4
public static void say(float obj) {
System.out.println("float");
}

// 5
public static void say(double obj) {
System.out.println("double");
}

// 6
public static void say(Character obj) {
System.out.println("Character");
}

// 7
public static void say(Serializable obj) {
System.out.println("Serializable");
}

// 9
public static void say(char... obj) {
System.out.println("char...");
}
}

BBBBBBB
CCCCCCC
char