1, VO: value object value object. It is usually used for data transfer between business layers. Like PO , it only contains data. But it should be an abstracted business object, which can correspond to a table or not, depending on the needs of the business.
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When the String[] type prints tosring, it is displayed as a memory space. At this time, it can be judged that the value has been successfully received according to the key.
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When judging the conditions, pay attention to the writing of the fuzzy query, and the String type can subtract the spaces of the string class through trim().
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Note: Value is the value when the form is submitted, and if it is assigned a value, it can be loaded into the dialog box during initialization.
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Long is a wrapper class for the basic type long. When operating on a basic type, it is usually converted into the corresponding wrapper class to use the corresponding method.
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Note the difference between if and foreach.
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Type conversion?