JAVA基本語法

1.關鍵字（key word）

關鍵字是Java語言特別賦予的具備特殊含義的字符串     關鍵字的特色：全部的關鍵字必須小寫

訪問權限修飾符的關鍵字  

private　　protected　　public　　　

定義基本數據類型的關鍵字

byte　　char　　short　　int　　long　　float　　double　　boolean

類、方法和變量的關鍵字

abstract　　class　　extends　　final　　implements　　interface　　native　　new　　static　　strictfp　　synchronized　　transient　　volatile

程序控制語句的關鍵字

break　　case　　continue　　default　　do　　else　　for　　if　　instanceof　　return　　switch　　while

用於錯誤處理的關鍵字

assert　　catch　　finally　　throw　　throws　　try

包相關的關鍵字

import　　package

變量引用相關的關鍵字

super　　this　　void

2.保留字（reserve word）

現有的Java版本還沒有使用，可是之後版本可能會做爲關鍵字使用，所以本身命名時須要避免使用保留字。

goto    const   null

3.標識符（Identifier）

在Java中對各類變量、方法、類進行命名時使用的字符序列稱爲標識符

全部的標識符都應該以字母（A-Z 或者 a-z）,美圓符（$）、或者下劃線（_）開始

首字符以後能夠是字母（A-Z 或者 a-z）,美圓符（$）、下劃線（_）或數字的任何字符組合

標識符不能包含空格、不能以數字開頭

關鍵字不能用做標識符、標識符是大小寫敏感的

合法標識符舉例：age、$salary、_value、__1_value

非法標識符舉例：123abc、-salary

Java中命名規範

包名：全部的字母都是小寫。如：helloword

類名/接口名：全部的單詞首字母大寫。如：Helloword

變量名：多個單詞組成，第一個單詞首字母小寫，第二個單詞開始每一個單詞首字母大寫如：passengerOrderNum

常量名：全部的字母都是大寫，多個單詞時，每一個單詞使用下劃線鏈接：hello_wold

4.變量

5.運算符

6.程序流程控制
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