toString的作用就是对对象进行“自我介绍”，一般子类对父类提供的toString都不满意，都要进行重写

    toString()方法会返回一个“以文本方式表达”此对象的字符串

    • IDEA快捷键
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        1.   - ![image.png](https://cdn.nlark.com/yuque/0/2021/png/2560440/1629251604825-28fd1589-5abf-4730-afac-1c34b58daa27.png#clientId=u19fd46e1-ebc7-4&from=paste&height=96&id=u83220595&margin=%5Bobject%20Object%5D&name=image.png&originHeight=192&originWidth=324&originalType=binary&ratio=1&size=6632&status=done&style=none&taskId=u03c57bce-aa36-45fa-bb25-02f7038795d&width=162)
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