blocks|key|4648580|text|不要使用myString+==+""，在java中，这将是myString.equals("")，这也是不推荐的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4648581|isBlank与isEmpty不一样，它实际上取决于您的用例。|4648582|isBlank检查一个字符序列是否有0长度，或者所有索引都是空白。isEmpty只检查字符序列长度是否为0。|4648583|/**
+*+Returns+`true`+if+this+string+is+empty+or+consists+solely+of+whitespace+characters.
+*/
public+fun+CharSequence.isBlank():+Boolean+=+length+==+0+%7C%7C+indices.all+{+this[it].isWhitespace()+}


/**
+*+Returns+`true`+if+this+char+sequence+is+empty+(contains+no+characters).
+*/
@kotlin.internal.InlineOnly
public+inline+fun+CharSequence.isEmpty():+Boolean+=+length+==+0|code-block|syntax|javascript|4648584|entityMap^0|4|E|T|J|0|0|7|8|7|0|0|7|X|7|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$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]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|15|8|@]|D|@]|E|$M|N]]|$1|O|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|P|$]]

Don't use <code>myString == ""</code>, in java this would be <code>myString.equals("")</code> which also isn't recommended.

<code>isBlank</code> is not the same as <code>isEmpty</code> and it really depends on your use-case.

<code>isBlank</code> checks that a char sequence has a 0 length or that all indices are white space. <code>isEmpty</code> only checks that the char sequence length is 0.

<pre><code>/**
 * Returns `true` if this string is empty or consists solely of whitespace characters.
 */
public fun CharSequence.isBlank(): Boolean = length == 0 || indices.all { this[it].isWhitespace() }


/**
 * Returns `true` if this char sequence is empty (contains no characters).
 */
@kotlin.internal.InlineOnly
public inline fun CharSequence.isEmpty(): Boolean = length == 0
</code></pre>

blocks|key|4648681|text|如果要测试字符串是否完全等于空字符串isEmpty，请使用""。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4648682|当您想测试字符串是否为空或仅由空白(""，"+++")组成时，请使用""。|4648683|避免使用==+""。|4648684|entityMap^0|I|7|T|2|0|I|2|L|5|Y|2|0|4|5|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|K|$]]

Use <code>isEmpty</code> when you want to test that a String is exactly equal to the empty string <code>""</code>.

Use <code>isBlank</code> when you want to test that a String is empty or only consists of whitespace (<code>""</code>, <code>" "</code>).

Avoid using <code>== ""</code>.

blocks|key|399951|text|对于String?+(可空字符串)数据类型，我使用.isNullOrBlank()|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|399952|对于String，我使用.isBlank()|399953|为什么？因为大多数情况下，我不希望允许字符串带有空格(+.isBlank()检查空白和空字符串)。如果您不关心空格，那么分别使用.isNullorEmpty()和.isEmpty()来表示String?和String。|399954|entityMap^0|2|7|P|G|0|2|6|C|A|0|S|A|1S|G|29|A|2M|7|2U|6|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]|$9|10|A|11|B|C]|$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|K|$]]

For <code>String?</code> (nullable String) datatype, I use <code>.isNullOrBlank()</code>
For <code>String</code>, I use <code>.isBlank()</code>
Why? Because most of the time, I do not want to allow Strings with whitespace (and <code>.isBlank()</code> checks whitespace as well as empty String). If you don't care about whitespace, use <code>.isNullorEmpty()</code> and <code>.isEmpty()</code> for <code>String?</code> and <code>String</code>, respectively.

blocks|key|4648711|text|可以使用isNullOrBlank()检查字符串是否为空或空。此方法认为空格仅为空字符串。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4648712|下面是一个用法示例：|4648713|val+s:+String?+=+null
println(s.isNullOrBlank())
val+s1:+String?+=+""
println(s1.isNullOrBlank())
val+s2:+String?+=+"+++++"
println(s2.isNullOrBlank())
val+s3:+String?+=+"++a+"
println(s3.isNullOrBlank())|code-block|syntax|javascript|4648714|这个片段的输出是：|4648715|true
true
true
false|4648716|entityMap^0|4|F|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|X|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|R|$]]

You can use <code>isNullOrBlank()</code> to check is a string is null or empty. This method considers spaces only strings to be empty.

Here is a usage example:

<pre><code>val s: String? = null
println(s.isNullOrBlank())
val s1: String? = ""
println(s1.isNullOrBlank())
val s2: String? = " "
println(s2.isNullOrBlank())
val s3: String? = " a "
println(s3.isNullOrBlank())
</code></pre>

The output of this snippet is:

<pre><code>true
true
true
false
</code></pre>

blocks|key|399962|text|Kotlin有两种方法可用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|399963|isNullOrBlank()|ordered-list-item|399964|isNullOrEmpty()|399965|不同之处在于：|399966|data+=+"+"+//+this+is+a+text+with+blank+space+
+
println(data.isNullOrBlank()?.toString())++//true
println(data.isNullOrEmpty()?.toString())++//false|code-block|syntax|javascript|399967|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Q|8|@]|9|@]|A|$]]|$1|E|3|F|5|D|7|R|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|K|7|T|8|@]|9|@]|A|$L|M]]|$1|N|3|-4|5|6|7|U|8|@]|9|@]|A|$]]]|O|$]]

There are two methods available in Kotlin.
<ol>
<li>isNullOrBlank()</li>
<li>isNullOrEmpty()</li>
</ol>
And the difference is:
<pre class="lang-kotlin prettyprint-override"><code>data = &quot; &quot; // this is a text with blank space 
 
println(data.isNullOrBlank()?.toString()) //true
println(data.isNullOrEmpty()?.toString()) //false
</code></pre>

blocks|key|184972|text|正如注释中所提到的，您可以使用ifBlank，如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|184973|fun+getSomeValue():+String+{
++//+...
++val+foo+=+someCall()
++return+foo.ifBlank+{+"some-default"+}
}|code-block|syntax|javascript|184974|文档：https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/if-blank.html|184975|entityMap|0|LINK|mutability|MUTABLE|url|https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/if-blank.html^0|F|7|0|0|3|1Y|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|Y|8|@]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|M|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

As someone mentioned in the comments, you can use <code>ifBlank</code>, like so:
<pre class="lang-kotlin prettyprint-override"><code>fun getSomeValue(): String {
 // ...
 val foo = someCall()
 return foo.ifBlank { &quot;some-default&quot; }
}
</code></pre>
Documentation: <a href="https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/if-blank.html" rel="nofollow noreferrer">https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/if-blank.html</a>

In Java, we've always been reminded to use <code>myString.isEmpty()</code> to check whether a String is empty. In Kotlin however, I find that you can use either <code>myString == ""</code> or <code>myString.isEmpty()</code> or even <code>myString.isBlank()</code>.

Are there any guidelines/recommendations on this? Or is it simply "anything that rocks your boat"?

Thanks in advance for feeding my curiosity. :D

Checking if string is empty in Kotlin

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。

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在Java中，我们总是被提醒使用myString.isEmpty()来检查字符串是否为空。但是，在Kotlin中，我发现您可以使用myString == ""或myString.isEmpty()，甚至可以使用myString.isBlank()。在这方面是否有任何指导方针/建议？还是简单地说“任何东西都会动摇你的船”...

问检查Kotlin中的字符串是否为空
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