import java.util.Collection;
import java.util.HashMap;
import java.util.Map;


public class Main {
	public static void main(String[] args) {
		Son s = new Son();
		HashMap hashMap = new HashMap();
		System.out.println("**** 子类父类参数前置条件相同，覆写 ****");
		s.doSth(hashMap);
		System.out.println("**** 子类参数前置条件比父类大，相当于方法重载 ****");
		s.doSth1(hashMap);
		s.doSth1((Map)hashMap);
		System.out.println("**** 父类参数前置条件比子类大 ****");
		s.doSth2(hashMap);
		s.doSth2((Map)hashMap);
	}
}

class Father{
	public Father() {
		System.out.println("Father");
	}
	
	public Collection doSth(HashMap map){
		System.out.println("Father->doSth");
		return map.values();
	}
	
	public Collection doSth1(HashMap map){
		System.out.println("Father->doSth1");
		return map.values();
	}
	
	public Collection doSth2(Map map){
		System.out.println("Father->doSth2");
		return map.values();
	}
}

class Son extends Father{
	public Son() {
		System.out.println("Son");
	}
	
	public Collection doSth(HashMap map){
		System.out.println("Son->doSth");
		return map.values();
	}
	
	public Collection doSth1(Map map){
		System.out.println("Son->doSth1");
		return map.values();
	}
	
	public Collection doSth2(HashMap map){
		System.out.println("Son->doSth2");
		return map.values();
	}
}

Father
Son
**** 子类父类参数前置条件相同，覆写 ****
Son->doSth
**** 子类参数前置条件比父类大，相当于方法重载 ****
Father->doSth1
Son->doSth1
**** 父类参数前置条件比子类大 ****
Son->doSth2
Father->doSth2