为什么我写的好像会提示方法没有创建？

package com.Traffic;

public class Plane extends Trasportation {
	public void methods(){
		int num=200;
		System.out.println("飞机可以在空中载"+num+"人");
	}
}

package com.Traffic;

public class Buss extends Trasportation {
	public void methods(){
		int num=60;
		System.out.println("汽车可以在路上载"+num+"人");
	}
}

package com.Traffic;

public class Ship extends Trasportation {

public void methods(){

int num=300;

System.out.println("轮船可以在海上载"+num+"人");

}

}

package com.Traffic;

public class Trasportation {

public static void main(String[] args) {

Trasportation obj1=new Trasportation();

Trasportation obj2=new Ship();

Trasportation obj3=new Plane();

Trasportation obj4=new Buss();

obj3.methods();

obj2.methods();

obj4.methods();

}

}