往Map中添加对象出现 java.lang.NullPointerException

package game;

public class Paizus {

public int ID;

public String name;

public Paizus(int ID, String name) {

this.ID=ID;

this.name=name;

}

}

package game;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Set;

public class Sumgames{

public Map<String,Paizus>newmap;

public void Sumgame() {

this.newmap=new HashMap<String,Paizus>();

}

public void pukepai() {

Paizus paizus=new Paizus(0, "方片4");

newmap.put("0",paizus);

}

public static void main(String[] args) {

Sumgames test=new Sumgames();

test.pukepai();

}

}