java - java.lang.Object@19821f 在 Java 中是什么意思？

Question

java.lang.Object@19821f 是什么意思？这是我尝试在没有任何赋值的情况下打印对象类型变量时的输出。代码:

Object object = new Object();
System.out.println(object);

Answer 1

RTFM，Object#toString :

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character '@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())

重要的是要注意在幕后，System.out.println 调用其参数的 toString 方法。