打印 对象 java,我们为什么不能打印在java中直接对象？

We can print an array easily using System.out.println(though array is also a kind of object in java) but why we can't print an object directly without override toString() method?

For example:

int array[]=new int(2);

array[0]=10;

System.out.println(array[0]); //it works

Object obj=new Object();

System.out.println(obj); //it shows the classname and some value i don't know

解决方案

"it shows the classname and some value i don't know"

Well, that's how an Object instance is printed, and for instances of Object class (i.e. not sub-classes of Object) you can't override toString.

For your custom sub-classes of Object, you must decide yourself how you wish the String representation of the object to look like (by overriding toString). Java doesn't decide it for you.