In this context, where this is the right-hand side of a String concatenation expression (using the plus sign), this.toString is invoked implicitly.

在这里的上下文中，this在一个String的链接表达式(使用加号)的右边，this . toString被隐式地调用了。

youdao

String players practice moving the fingers of the left hand up and down, while drawing the bow to and fro with the right arm — two entirely different movements.

弦乐器的演奏者练习的则是在左手的手指上下滑动的同时，用右手前后拉动琴弓——两个截然不同的动作。

youdao

String players practice moving the fingers of the left hand up and down, while drawing the bow to and fro with the right arm-two entirely different movements.

弦乐器的演奏者练习的则是在左手的手指上下滑动的同时，用右手前后拉动琴弓——两个截然不同的动作。

youdao