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本节笔记

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#1 Created at ... [Delete] [Delete and Lock User]

判断引用类型的变量内容是否相等,必须使用equals()方法:

 if (s1.equals(s2))

如果变量s1为null,会报NullPointerException:

要避免NullPointerException错误,可以利用短路运算符&&:if (s1 != null && s1.equals("hello"))


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