深入java虚拟机（一）

package com.ygl;

 class  SingleTon{


private static SingleTon singleTon=new SingleTon();


public static int counter1;

public static int counter2=0;


public SingleTon(){

counter1++;

counter2++;

}


public static SingleTon getInstance(){

return singleTon;

}

 }

 public class MyTest {

 public static void main(String[] args) {

SingleTon singleTon=SingleTon.getInstance();//触发类加载，先为静态变量分配内存（以及默认初始值，执行=左边），后赋值，执行=右边

System.out.println("counter1="+singleTon.counter1);

System.out.println("counter1="+singleTon.counter2);

 }
}
//******************************************
counter1=1
 counter1=0//*********************************************
class  SingleTon{


public static int counter1;
public static int counter2=0;
private static SingleTon singleTon=new SingleTon();
public SingleTon(){
counter1++;
counter2++;
}

public static SingleTon getInstance(){
return singleTon;
}
 }
 public class MyTest {
 public static void main(String[] args) {
SingleTon singleTon=SingleTon.getInstance();
System.out.println("counter1="+singleTon.counter1);
System.out.println("counter1="+singleTon.counter2);
 }}
 //****************************************************** 
counter1=1
 counter1=1