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好吧问答库 > java中有没有判断一个变量或者对象是否已经存在的方法？？？拜请大牛指点，很急..............

java中有没有判断一个变量或者对象是否已经存在的方法？？？拜请大牛指点，很急..............

2025年04月07日 00:25

有3个网友回答

网友（1）：

集合里有这类的方法，比如map中看是否存在某个key或者object，list里也有。

网友（2）：

如果是基本数据类型，如int没有办法，如果是对象很好办的
if obj == null --->如果为null，就是还没有分配内存，自然是不存在了

网友（3）：

isEmpty(),exits()是判断是否为空和是否存在的。

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