blocks|key|720096|text|对于字符串比较，使用equals方法，因为它比使用==运算符更可靠(它比较内容，而==比较引用)：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|720097|尝试使用equals方法：|720098|if(dataSource.substring(0,1).equals("/")){|code-block|syntax|javascript|720099|entityMap^0|A|6|P|2|15|2|0|4|6|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|N|$]]

For string comparisons use <code>equals</code> method, as it is more reliable than using <code>==</code> operator (it compares the content while <code>==</code> comnpares the references ) :

Try using <code>equals</code> method :

<pre><code>if(dataSource.substring(0,1).equals("/")){
</code></pre>

blocks|key|4552018|text|请使用.equals|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4552019|if("/".equals(dataSource.substring(0,1))){
++++System.out.println("trailing+forward+slash,+delete+it+");++
++++dataSource+=+dataSource.substring(1);
}|code-block|syntax|javascript|4552020|代替==|4552021|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

please use .equals

<pre><code>if("/".equals(dataSource.substring(0,1))){
 System.out.println("trailing forward slash, delete it "); 
 dataSource = dataSource.substring(1);
}
</code></pre>

instead of ==

blocks|key|720214|text|如果你只想测试第一个字符，你可以尝试这个方法，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|720215|dataSource.charAt(0)=='/'|offset|length|style|BOLD|720216|entityMap^0|0|0|P|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

If you want to test only, the first character , you can try the method,

dataSource.charAt(0)=='/'

blocks|key|124182|text|对于字符串比较，您应该使用.equals，因此|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|124183|if(dataSource.substring(0,1)+==+"/")|code-block|syntax|javascript|124184|应该是|124185|if+("/".equals(dataSource.substring(0,1)))|124186|entityMap^0|D|7|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

you should use <code>.equals</code> for string comparrisons
 so 

<pre><code>if(dataSource.substring(0,1) == "/")
</code></pre>

should be

<pre><code>if ("/".equals(dataSource.substring(0,1)))
</code></pre>

blocks|key|719932|text|您正在将字符串与==进行比较，这意味着您将检查这两个字符串是否确实是相同的字符串引用。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|719933|使用equal()检查两个字符串是否包含相同的字符。|719934|请参阅：http://www.leepoint.net/notes-java/data/expressions/22compareobjects.html|719935|entityMap|0|LINK|mutability|MUTABLE|url|http://www.leepoint.net/notes-java/data/expressions/22compareobjects.html^0|8|2|0|2|7|0|4|21|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|X|8|@]|D|@$9|Y|A|Z|1|10]]|E|$]]|$1|J|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

You're comparing strings with <code>==</code>, which means you're checking to see if these two strings are literally the same string reference.

Use <code>equal()</code> to check and see if two strings contain the same characters. 

See: <a href="http://www.leepoint.net/notes-java/data/expressions/22compareobjects.html" rel="nofollow">http://www.leepoint.net/notes-java/data/expressions/22compareobjects.html</a>

blocks|key|4552011|text|使用.equals(Object)或.equalsIgnoreCase(String)比较字符串。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4552012|entityMap^0|2|F|I|P|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

Use <code>.equals(Object)</code> or <code>.equalsIgnoreCase(String)</code> for comparing Strings.

blocks|key|720170|text|您需要执行dataSource.substring(0,1).equals("/")，它实际检查字符串的内容。==仅检查两端是否为同一对象。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|720171|entityMap^0|5|11|1J|2|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

You need to do <code>dataSource.substring(0,1).equals("/")</code>, which actually checks the content of the strings. <code>==</code> only checks whether both sides are the same object.

blocks|key|4070215|text|尝尝这个|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4070216|if+((“要检查的字符串”).equals(MyString)){+doSomething()；}|4070217|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Try this

if (("some string to check").equals(myString)){
 doSomething();
}

blocks|key|4552135|text|在比较值时，请始终使用equals。话虽如此，您可以只使用indexOf方法来实现您的目的|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4552136|+++if+(dataSource.indexOf('/')+==+0)+{
++++++++dataSource+=+dataSource.substring(1);
++++}|code-block|syntax|javascript|4552137|entityMap^0|B|6|T|7|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Always use <code>equals</code> when comparing values. Having said that you can just use <code>indexOf</code> method for your purpose 

<pre><code> if (dataSource.indexOf('/') == 0) {
 dataSource = dataSource.substring(1);
 }
</code></pre>

blocks|key|4070320|text|String+dataSource+=+"/hell";

++++++++if(dataSource.substring(0,1).equalsIgnoreCase("/")){
++++++++++++System.out.println("trailing+forward+slash,+delete+it+");++
++++++++++++dataSource+=+dataSource.substring(1);
++++++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4070321|运行这个程序。这起作用了..|unstyled|4070322|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>String dataSource = "/hell";

 if(dataSource.substring(0,1).equalsIgnoreCase("/")){
 System.out.println("trailing forward slash, delete it "); 
 dataSource = dataSource.substring(1);
 }
</code></pre>

run this program. this is working..

blocks|key|720340|text|为什么要使用字符串？你只是在为自己制造这个问题。使用提供的数据类型：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|720341|InetAddress+dataSource+=+data.getInetAddress();|code-block|syntax|javascript|720342|或|720343|SocketAddress+dataSource+=+data.getRemoteSocketAddress();|720344|然后，在这两种情况下都有一个语义感知的.equals()方法。|offset|length|style|CODE|720345|entityMap^0|0|0|0|0|J|9|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@$M|X|N|Y|O|P]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Why use a String? You're just creating this problem for yourself. Use the datatype provided:

<pre><code>InetAddress dataSource = data.getInetAddress();
</code></pre>

or

<pre><code>SocketAddress dataSource = data.getRemoteSocketAddress();
</code></pre>

Then you have a semantically-aware <code>.equals()</code> method in both cases.

When I grab the IP Address from my open socket, as someone has sent me a stream, I noticed that the IP has a forward-slash.

I just plan to simply omit it. But first I want to validate the first character in the string is the forward-slash:

<pre><code>String dataSource = data.getAddress().toString();

if(dataSource.substring(0,1) == "/"){
 System.out.println("trailing forward slash, delete it "); 
 dataSource = dataSource.substring(1);
}
</code></pre>

This IF statement isn't being detected.

Anyone see what I'm doing wrong?

Java - If statement not working (comparing strings)

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

当我从我打开的套接字中获取IP地址时，因为有人向我发送了一个流，我注意到IP有一个正斜杠。我只打算简单地省略它。但首先，我想验证字符串中的第一个字符是正斜杠：String dataSource = data.getAddress().toString();if(dataSource.substring(0,1) == "/"){    System.out.println("trailing fo

问Java - If语句不工作(比较字符串)
EN

回答 11

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问Java - If语句不工作(比较字符串)EN

回答 11

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问Java - If语句不工作(比较字符串)
EN