为什么不调用finalize?

Q1.As far as I understand, finalize() gets called when object is out of scope and JVM is about to collect garbage. I thought finalize() method is called automatically by garbage collector, but it does not seems to work in this case. What is the explanation? Why is the need for me to explicitly call finalize() method?

public class MultipleConstruct {
    int x,y;    
    public MultipleConstruct(int x)
    {
        this.x= x;
        y=5;        
        System.out.println("ONE");
    }

    @Override
    protected void finalize() throws Throwable {
        // TODO Auto-generated method stub
        super.finalize();
        System.out.println("FINALIZED");
    }
    public static void main(String[] args) throws Throwable {
        MultipleConstruct construct = new MultipleConstruct(3);
    }
}

第二季度.另外，什么时候调用垃圾收集器?我知道 gc 是一个守护线程，由 JVM 根据剩余的堆大小调用.这是否意味着，JVM 等待程序使用资源的阈值限制，然后通知 gc 清除垃圾对象.

for(int i =0;i<1000000;i++)
    {
        MultipleConstruct construct = new MultipleConstruct(3);
        construct = null;
    }