10级《面向对象程序设计》第二章教学课件.ppt

第二章 Java 基础 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 学****目标: ?掌握标识符和关键字?熟练使用各种数据类型的定义、表示和引用?掌握算术、逻辑和布尔运算符?自动类型转换和强制类型转换 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 标识符 Java 保留字 Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. 标识符的命名规则一定要牢记啊?类名首字母大写; ?符号常量名全部字母大写; ?变量名、对象名、方法名、包名等标识符全部采用小写字母;如果标识符由多个单词构成,则首字母小写,其后单词的首字母大写,其余字母小写; Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. ?合法的标识符 identifier userName User_Name_sysval $change A98_23 _abc ?非法的标识符 2mail room# class A- 4 3_1 >the Evaluation only. Evaluation only. Created with Client Profile . Created with Client Profile . Copyright 2004-2011 Aspose Pty Ltd. Copyright 2004-2011 Aspose Pty Ltd. Java 保留字(又称关键字) 关键字不能作为标识符; 关键字不能作为标识符; 关键字是具有专门的意义和用途,不能当作一般的标识符使用,这些标识符称为保留字(reserved word), 下面列出了 java 语言中的所有保留字: abstract do implements protected throws abstract do implements protected throws boolean double import public transient boolean double import public transient break else instanceof return true this throw break else instanceof return true this throw byte extends int short try synchronized byte extends int short try synchronized case false interface static void continue case fa