java - 谁能解释下为什么输出是1,0吗

Question

class Singleton{
    private  static Singleton instance=new Singleton();
    public static int count;
    public static int count1=0;
    private Singleton(){
        count++;
        count1++;
        
    }
    public static Singleton  getInstance(){
        return instance;
    }
    
}
public class SingleTonDemo {
    public static void main(String[] args) {
        Singleton  instance=Singleton.getInstance();
        System.out.println(instance.count); //1
        System.out.println(instance.count1);//0
    }

Answer 1

因為你變數初始化順序的問題。

1. 創建Singleton对象，此时count，count1都为1

   private static Singleton instance = new Singleton();

2. 靜態初始化count1，这里又将count1赋值为0

   public static int count1 = 0;

3. 你想要2個都得1將instance初始化放置在count1下面即可。

   public static int count;
   public static int count1 = 0;
   private static Singleton instance = new Singleton();