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标签 : Java基础
五月份得知入职阿里云OS, 才开始学Java, 断断续续学习/使用半年, 越来越喜欢这个语言/工具. 后来被拥抱变化之后, 拿到的大部分offer是Java服务端研发; 一路走来, 踩了很多坑, 也有了一点小小的心得, 而且博客已经停更几个月, 今天就以博客形式把他记录下来吧.
2015下半年第一篇博客, 从最基础的Java注释开始:
程序员圈有一个笑话
最讨厌在写代码的时候写注释, 最讨厌别人的代码里面不写注释.
我自己亲身经历:
这段时间在微店实习, 第一个接手的项目是将原先北京团队的代码迁移到杭州, 由于底层技术架构的更换, 大部分代码需要重写, 前提是要理解原先的业务逻辑, 但当我在SVN上把代码拉下来, 看到意大利面似的一大坨代码里只有寥寥几行注释时, 整个人都不好了… 另一个遇到场景, 有时自己的代码有Bug, 或者需要重构, 此时就需要Review代码, 可是突然发现自己已经很难理解原先逻辑了(很可能这段代码只是你前几天刚刚写的), 因为我们已经很难回到当时状态. 还有一个重要的原因就是文档, 往往一个系统被开发出来, 文档要么不全, 要么更新落后, 如果后人要接手这一套系统, 就必须直接阅读源码, 如果此时在代码的关键逻辑之处能够有一两行注释提示, 新人就没有必要绞尽脑汁去猜测当时的设计方案了. 后来自己写代码时就尽量写注释提示, 虽然不一定完全按照下面的注释规范, 但会尽量用 最简单的语言把问题阐述清楚, 在逻辑转折之处添加几行说明, 无论是自己还是未来的接手人, 都会对现在的你感激不尽.Java提供三种注释方式: 单行注释、多行注释、文档注释.
command+/: 以//快速注释一行或多行 : // Integer[] array = new Integer[10];// for (int i = 0; i < array.length; ++i){ // array[i] = new Integer(i);// } command+option+/: 以/**/快速注释一行或多行
/* Integer[] array = new Integer[10]; for (int i = 0; i < array.length; ++i){ array[i] = new Integer(i); }*/ /** */ /** * Initializes a newly created {@code String} object so that it represents * the same sequence of characters as the argument; in other words, the * newly created string is a copy of the argument string. Unless an * explicit copy of {@code original} is needed, use of this constructor is * unnecessary since Strings are immutable. * * @param original * A {@code String} */ # javadoc 注释标签语法
| 标签 | 作用域 | 说明 |
|---|---|---|
| @author | 类 | 标明开发该类模块作者 |
| @version | 类 | 标明该类模块的版本 |
| @see | 类, 属性, 方法 | 参考转向(相关主题) |
| @param | 方法 | 对方法中某参数的说明 |
| @return | 方法 | 对方法返回值的说明 |
| @exception | 方法 | 抛出的异常类型 |
| @throws | 方法 | 与@exception相同 |
| @deprecated | 方法 | 不建议使用该方法 |
下面是我自己看到和用过的注释原则:
/** * TheStringclass represents character strings. All * string literals in Java programs, such as"abc", are * implemented as instances of this class. * (其他描述) * @author Lee Boynton * @author Arthur van Hoff * @author Martin Buchholz * @author Ulf Zibis * @see java.lang.Object#toString() * @see java.lang.StringBuffer * @see java.lang.StringBuilder * @see java.nio.charset.Charset * @since JDK1.0 */ public final class String implements java.io.Serializable, Comparable, CharSequence { ...}
/** * Initializes a newly created {@code String} object so that it represents * the same sequence of characters as the argument; in other words, the * newly created string is a copy of the argument string. Unless an * explicit copy of {@code original} is needed, use of this constructor is * unnecessary since Strings are immutable. * * @param original * A {@code String} */ public String(String original) { this.value = original.value; this.hash = original.hash; } /** * Returns true if, and only if, {@link #length()} is 0. * * @return true if {@link #length()} is 0, otherwise * false * * @since 1.6 */ public boolean isEmpty() { return value.length == 0; } /** The value is used for character storage. */ private final char value[]; /** Cache the hash code for the string */ private int hash; // Default to 0 /** use serialVersionUID from JDK 1.0.2 for interoperability */ private static final long serialVersionUID = -6849794470754667710L; /** * Class String is special cased within the Serialization Stream Protocol. * * A String instance is written initially into an ObjectOutputStream in the * following format: *** The String is written by methodTC_STRING(utf String) *DataOutput.writeUTF. * A new handle is generated to refer to all future references to the * string instance within the stream. */ private static final ObjectStreamField[] serialPersistentFields = new ObjectStreamField[0];
public boolean regionMatches(boolean ignoreCase, int toffset, String other, int ooffset, int len) { char ta[] = value; int to = toffset; char pa[] = other.value; int po = ooffset; // Note: toffset, ooffset, or len might be near -1>>>1. if ((ooffset < 0) || (toffset < 0) || (toffset > (long)value.length - len) || (ooffset > (long)other.value.length - len)) { return false; } while (len-- > 0) { char c1 = ta[to++]; char c2 = pa[po++]; if (c1 == c2) { continue; } if (ignoreCase) { // If characters don't match but case may be ignored, // try converting both characters to uppercase. // If the results match, then the comparison scan should // continue. char u1 = Character.toUpperCase(c1); char u2 = Character.toUpperCase(c2); if (u1 == u2) { continue; } // Unfortunately, conversion to uppercase does not work properly // for the Georgian alphabet, which has strange rules about case // conversion. So we need to make one last check before // exiting. if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) { continue; } } return false; } return true; } String(char[] value, boolean share) { // assert share : "unshared not supported"; this.value = value; } char[] val = value; /* avoid getfield opcode */ public boolean contentEquals(CharSequence cs) { if (value.length != cs.length()) return false; // Argument is a StringBuffer, StringBuilder if (cs instanceof AbstractStringBuilder) { char v1[] = value; char v2[] = ((AbstractStringBuilder) cs).getValue(); int i = 0; int n = value.length; while (n-- != 0) { if (v1[i] != v2[i]) return false; i++; } return true; } // Argument is a String if (cs.equals(this)) return true; // Argument is a generic CharSequence char v1[] = value; int i = 0; int n = value.length; while (n-- != 0) { if (v1[i] != cs.charAt(i)) return false; i++; } return true; } 在此只推荐了我所知道和常用一些小工具, 欢迎同学补充.
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