JVM之对象头内存模型

JVM之对象头内存模型

这篇文章我们来看一下对象的内存结构。先上图

1、内存图

下面来验证一下

2、导入可视化工具

<!--java对象内存模型可视化工具-->
<dependency>
  <groupId>org.openjdk.jol</groupId>
  <artifactId>jol-core</artifactId>
  <version>0.9</version>
</dependency>

测试外部对象

public class Boy {
    byte aByte; //1
    boolean aBoolean;//1
    short aShort;//2
    int anInt;//4
    long aLong;//8
    char aChar;//2
    float aFloat;//4
    double aDouble;//8
}

@Test
public void test04(){
    String s = ClassLayout.parseInstance(new Boy()).toPrintable();
    System.out.println(s);
}

结果

测试内部类加子类对象

class Student extends MyTest{
    Byte aByte1;
    Integer integer;
    Short aShort1;
    Long aLong;
    Boolean[] booleans;
    Boolean aBoolean;
    boolean[] booleans1;
    String string;
    int[] ints;

    public void test(){

    }
}

@Test
public void test03(){

    Student student=new Student();
    String s=ClassLayout.parseInstance(student).toPrintable();
    System.out.println(s);
}