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@@ -12,9 +12,7 @@
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@@ -27,86 +25,61 @@
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@@ -489,14 +459,11 @@ fail:
<h2>一起来动手</h2>
<p>下面的这段代码，我们前面用过一次，我稍微做了点修改。我们这次重点来看编码的规范，有哪些地方你看着不顺眼，你会怎么改进？</p>
<pre><code>package com.example;
import java.util.Collections;
import java.util.List;
import javax.net.ssl.SNIServerName;
class ServerNameSpec {
final List&lt;SNIServerName&gt; serverNames;
ServerNameSpec(List&lt;SNIServerName&gt; serverNames) {
this.serverNames = Collections.&lt;SNIServerName&gt;unmodifiableList(serverNames);
}
@@ -616,7 +583,6 @@ static final String[] names = { &quot;Alice&quot;, &quot;Bob&quot;, &quot;Tom&qu
<p>所以为了让你更好地实践，我找了一段 Java 代码。你来试试，这段代码中有哪些名字可以优化？ 欢迎你把优化的代码发在评论里，我们亲自感受下如何优化代码名字。</p>
<pre><code>import java.util.HashMap;
import java.util.Map;
class Solution {
/**
* Given an array of integers, return indices of the two numbers
@@ -666,14 +632,12 @@ if ((firstName != null) &amp;&amp; (lastName != null))
<p>下面这个简图，可以直观地表示这种代码块的布局方式。</p>
<p><img src="assets/4d810b8acbdc3a5413f53a432dc08eb7.png" alt="img" />或者，也可以参考下面的代码示例。 这段代码，也包含了使用空格区分同一行代码内部的信息块。</p>
<pre><code>package coding;
public class CodingFormat {
public static void main(String[] args) {
System.out.println(
&quot;German say hello with &quot;
+ Greeting.GERMAN.getGreeting());
}
private static enum Greeting {
ENGLISH (&quot;English&quot;, &quot;Hello&quot;),
SPANISH (&quot;Spanish&quot;, &quot;Hola&quot;),
@@ -716,19 +680,16 @@ public class CodingFormat {
<p>上面的 CodingFormat 例子中，我们使用了四个空格作为一个缩进单元。下面，我们看看两个空格的缩进，以及八个空格的缩进效果。</p>
<p>两个空格的缩进：</p>
<pre><code>package coding;
public class CodingFormat {
public static void main(String[] args) {
System.out.println(
&quot;German say hello with &quot; + Greeting.GERMAN.getGreeting());
}
private static enum Greeting {
ENGLISH (&quot;English&quot;, &quot;Hello&quot;),
SPANISH (&quot;Spanish&quot;, &quot;Hola&quot;),
GERMAN (&quot;German&quot;, &quot;Hallo&quot;),
MANDARIN (&quot;Mandarin&quot;, &quot;Ni Hao&quot;);
private final String language;
private final String greeting;
@@ -751,14 +712,12 @@ public class CodingFormat {
<p>两个空格的缩进，视觉上，缩进线靠得太近，相对而言，更容易混淆代码的分块级别。这是两个空格缩进的一个小缺点。</p>
<p>我们再来看下八个空格的缩进：</p>
<pre><code>package coding;
public class CodingFormat {
public static void main(String[] args) {
System.out.println(
&quot;German say hello with &quot;
+ Greeting.GERMAN.getGreeting());
}
private static enum Greeting {
ENGLISH (&quot;English&quot;, &quot;Hello&quot;),
SPANISH (&quot;Spanish&quot;, &quot;Hola&quot;),
@@ -794,7 +753,6 @@ public class CodingFormat {
</code></pre>
<p>双目运算符或者多目运算符，运算符前后都要使用空格：</p>
<pre><code>firstName != null
(firstName != null) &amp;&amp; (lastName != null)
</code></pre>
<h2>一行一个行为</h2>
@@ -803,7 +761,6 @@ public class CodingFormat {
<p>一个重要的原则是，每一行代码仅仅表示一个行为。这样每一行的代码才是一个常规大小的、可以识别的基础信息块。</p>
<p>比如说，下面的这行代码就包含了两个行为，一个是判断行为，一个是执行行为。 两个行为放在一行，这样的代码不仅看起来有些乱，我们的大脑处理起来也有些懵。</p>
<pre><code>if (variable != null) variable.doSomething();
</code></pre>
<p>如果分隔开这两个行为，信息块的区隔会更明显，代码会更清晰：</p>
<pre><code>if (variable != null) {
@@ -836,11 +793,9 @@ public class CodingFormat {
</ul>
<pre><code>anObject.methodOne(parameterForMethodOne,
anObject.methodTwo(parameterForMethodTwo));
/ conventional indentation
int runningMiles = runningSpeedOne * runningTimeOne
+ runningSpeedTwo * runningTimeTwo;
// confusing indentation
int runningMiles = runningSpeedOne
* runningTimeOne + runningSpeedTwo
@@ -860,13 +815,11 @@ int runningMiles = runningSpeedOne
anObject.methodTwo(parameterOneForMethodTwo,
parameterTwoForMethodTwo,
parameterThreeForMethodTwo));
// bad indentation
if ((conditionOne &amp;&amp; conditionTwo)
|| (conditionThree &amp;&amp; conditionFour)) {
doSomething();
}
// a better indentation, using 8 spaces for the indentation
if ((conditionOne &amp;&amp; conditionTwo)
|| (conditionThree &amp;&amp; conditionFour)) {
@@ -880,7 +833,6 @@ if ((conditionOne &amp;&amp; conditionTwo)
<p>还记得我们上一节的练习题吗？上次我们改名字，这次我们来修改一下代码的编排。欢迎你把优化的代码公布在讨论区，也可以写下你的优化思路，我们一起来看看编排优化后的代码是不是更好阅读了呢？</p>
<pre><code>import java.util.HashMap;
import java.util.Map;
class Solution {
/**
* Given an array of integers, return indices of the two numbers
@@ -963,9 +915,7 @@ private static void verifyLength(
ByteBuffer buffer, int requiredLength) {
...
}
String myString; // using end-to-line comment
// This is a multiple line comment. This is a multiple
// line comment.
if (!myString.isEmpty()) {
@@ -977,7 +927,6 @@ if (!myString.isEmpty()) {
<pre><code>/*
* This is a multiple line comment. This is a multiple
* line comment.
if (programingLanguage.equals(&quot;Java&quot;)) {
...
} */
@@ -1014,7 +963,6 @@ if (!myString.isEmpty()) {
<p>还记得我们上一节的练习题吗？前面，我们改了名字，改了编排。这一次，我们来修改注释。认真读一下这段代码，看看有需要增加或者修改注释的地方吗？欢迎你把优化的代码公布在讨论区，我们一起来感受修改后的代码是不是更好阅读，更好维护。</p>
<pre><code>import java.util.HashMap;
import java.util.Map;
class Solution {
/**
* Given an array of integers, return indices of the two numbers
@@ -1117,7 +1065,6 @@ class Solution {
import java.util.HashMap;
import java.util.List;
import java.util.Map;
class Solution {
/**
* Return a list of the words in words that match the given pattern.
@@ -1145,7 +1092,6 @@ class Solution {
ans.add(word);
return ans;
}
public boolean match(String word, String pattern) {
Map&lt;Character, Character&gt; M = new HashMap();
for (int i = 0; i &lt; word.length(); ++i) {
@@ -1235,7 +1181,6 @@ public String(byte ascii[], int hibyte) {
<p>做好这件事情，需要我们使用 Deprecated 注解，并且用一切可以使用的办法，广而告之。对于代码而言，要在声明中使用 Deprecated 注解；在规范描述中，说明废弃的原因以及替代的办法；对于有计划要删除的接口，要注明计划删除的版本号。</p>
<p>下面是两个可以参照的 Java 代码废弃接口的例子：</p>
<pre><code>java/lang/String.java:
/**
* Counts the number of stack frames in this thread. The thread must
* be suspended.
@@ -1253,7 +1198,6 @@ public String(byte ascii[], int hibyte) {
@Deprecated(since=&quot;1.2&quot;, forRemoval=true)
public native int countStackFrames();
java.security.Certificate.java:
/**
* &lt;p&gt;This is an interface of abstract methods for managing a
* variety of identity certificates.
@@ -1445,7 +1389,6 @@ boolean isAuthenticatedUser(String userName, String password) {
<p>欢迎你把优化的代码公布在讨论区，我们一起来讨论，看哪些地方我们可以做得更好。也欢迎你把今天的内容分享给协作的小伙伴，和他一起进步。</p>
<pre><code>import java.util.HashMap;
import java.util.Map;
class Solution {
/**
* Given an array of integers, return indices of the two numbers
@@ -1570,7 +1513,6 @@ class Solution {
<p>也欢迎点击“请朋友读”，把这篇文章分享给你的朋友或者同事，一起来体验修改代码的快感。</p>
<pre><code>import java.util.HashMap;
import java.util.Map;
class Solution {
/**
* Given an array of integers, return indices of the two numbers
@@ -2032,7 +1974,6 @@ class Solution {
<p>欢迎你把优化的代码公布在讨论区，我们一起来看看性能优化后的代码可以是什么样的？</p>
<pre><code>import java.util.HashMap;
import java.util.Map;
class Solution {
/**
* Given an array of integers, return indices of the two numbers
@@ -2115,7 +2056,6 @@ class Solution {
<p>欢迎你在留言区讨论上面的问题，我们一起来看看这一小段代码，是不是可以做的更好？</p>
<pre><code>import java.util.HashMap;
import java.util.Map;
class Solution {
/**
* Given an array of integers, return indices of the two numbers
@@ -2334,12 +2274,10 @@ boolean isRegisteredUser(String userName) {
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@@ -2348,11 +2286,9 @@ boolean isRegisteredUser(String userName) {
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@@ -2383,7 +2317,5 @@ boolean isRegisteredUser(String userName) {
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