blocks|key|122692|text|来自@arshajii的公认答案是完全正确的。然而，更明确地说，下面这样说：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|122693|StringUtils.isBlank()|122694|+StringUtils.isBlank(null)++++++=+true
+StringUtils.isBlank("")++++++++=+true++
+StringUtils.isBlank("+")+++++++=+true++
+StringUtils.isBlank("bob")+++++=+false++
+StringUtils.isBlank("++bob++")+=+false|code-block|syntax|javascript|122695|StringUtils.isEmpty|122696|+StringUtils.isEmpty(null)++++++=+true
+StringUtils.isEmpty("")++++++++=+true++
+StringUtils.isEmpty("+")+++++++=+false++
+StringUtils.isEmpty("bob")+++++=+false++
+StringUtils.isEmpty("++bob++")+=+false|122697|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

The accepted answer from @arshajii is totally correct. However just being more explicit by saying below,

StringUtils.isBlank() 

<pre><code> StringUtils.isBlank(null) = true
 StringUtils.isBlank("") = true 
 StringUtils.isBlank(" ") = true 
 StringUtils.isBlank("bob") = false 
 StringUtils.isBlank(" bob ") = false
</code></pre>

StringUtils.isEmpty

<pre><code> StringUtils.isEmpty(null) = true
 StringUtils.isEmpty("") = true 
 StringUtils.isEmpty(" ") = false 
 StringUtils.isEmpty("bob") = false 
 StringUtils.isEmpty(" bob ") = false
</code></pre>

blocks|key|122507|text|StringUtils.isBlank()还将检查是否为null，而如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|122508|String+foo+=+getvalue("foo");
if+(foo.isEmpty())|code-block|syntax|javascript|122509|如果foo为null，则将引发NullPointerException。|122510|entityMap^0|0|L|0|0|2|3|F|K|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|N|$]]

<code>StringUtils.isBlank()</code> will also check for null, whereas this:

<pre><code>String foo = getvalue("foo");
if (foo.isEmpty())
</code></pre>

will throw a <code>NullPointerException</code> if <code>foo</code> is null.

blocks|key|4628478|text|StringUtils.isBlank(foo)将为您执行null检查。如果执行foo.isEmpty()并且foo为null，则将引发NullPointerException。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4628479|entityMap^0|0|O|14|D|1J|3|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|O|8|@]|D|@]|E|$]]]|G|$]]

<code>StringUtils.isBlank(foo)</code> will perform a null check for you. If you perform <code>foo.isEmpty()</code> and <code>foo</code> is null, you will raise a NullPointerException.

blocks|key|4628664|text|isBlank()和isEmpty()之间唯一的区别是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4628665|StringUtils.isBlank("+")+++++++=+true+//compared+string+value+has+space+and+considered+as+blank

StringUtils.isEmpty("+")+++++++=+false+//compared+string+value+has+space+and+not+considered+as+empty|code-block|syntax|javascript|4628666|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The only difference between isBlank() and isEmpty() is:

<pre><code>StringUtils.isBlank(" ") = true //compared string value has space and considered as blank

StringUtils.isEmpty(" ") = false //compared string value has space and not considered as empty
</code></pre>

blocks|key|122643|text|对于空格(只返回空格)和空字符串，StringUtils.isBlank()返回true。实际上，它会修剪Char序列，然后执行检查。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|122644|当字符串参数中没有charsequence或字符串参数为空时，StringUtils.isEmpty()返回true。不同之处在于，如果字符串参数只包含false空间，则isEmpty()返回false。它认为空白是一种非空的状态。|122645|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|$]]

StringUtils.isBlank() returns true for blanks(just whitespaces)and for null String as well. Actually it trims the Char sequences and then performs check.

StringUtils.isEmpty() returns true when there is no charsequence in the String parameter or when String parameter is null. Difference is that isEmpty() returns false if String parameter contains just whiltespaces. It considers whitespaces as a state of being non empty.

blocks|key|122738|text|不使用第三方库，而使用Java11+isBlank()|type|unstyled|depth|inlineStyleRanges|entityRanges|data|122739|++++String+str1+=+"";
++++String+str2+=+"+++";
++++Character+ch+=+'\u0020';
++++String+str3+=ch%2B"+"%2Bch;

++++System.out.println(str1.isEmpty());+//true
++++System.out.println(str2.isEmpty());+//false
++++System.out.println(str3.isEmpty());+//false++++++++++++

++++System.out.println(str1.isBlank());+//true
++++System.out.println(str2.isBlank());+//true
++++System.out.println(str3.isBlank());+//true|code-block|syntax|javascript|122740|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Instead of using third party lib, use Java 11 isBlank() 

<pre><code> String str1 = "";
 String str2 = " ";
 Character ch = '\u0020';
 String str3 =ch+" "+ch;

 System.out.println(str1.isEmpty()); //true
 System.out.println(str2.isEmpty()); //false
 System.out.println(str3.isEmpty()); //false 

 System.out.println(str1.isBlank()); //true
 System.out.println(str2.isBlank()); //true
 System.out.println(str3.isBlank()); //true
</code></pre>

blocks|key|122673|text|public+static+boolean+isEmpty(String+ptext)+{
+return+ptext+==+null+%7C%7C+ptext.trim().length()+==+0;
}

public+static+boolean+isBlank(String+ptext)+{
+return+ptext+==+null+%7C%7C+ptext.trim().length()+==+0;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|122674|两者都有相同的代码，isBlank将如何处理空格，可能你指的是isBlankString，它有处理空格的代码。|unstyled|122675|public+static+boolean+isBlankString(+String+pString+)+{
+int+strLength;
+if(+pString+==+null+%7C%7C+(strLength+=+pString.length())+==+0)
+return+true;
+for(int+i=0;+i+<+strLength;+i%2B%2B)
+if(!Character.isWhitespace(pString.charAt(i)))
+return+false;
+return+false;
}|122676|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>public static boolean isEmpty(String ptext) {
 return ptext == null || ptext.trim().length() == 0;
}

public static boolean isBlank(String ptext) {
 return ptext == null || ptext.trim().length() == 0;
}
</code></pre>

Both have the same code how will isBlank handle white spaces probably you meant isBlankString this has the code for handling whitespaces.

<pre><code>public static boolean isBlankString( String pString ) {
 int strLength;
 if( pString == null || (strLength = pString.length()) == 0)
 return true;
 for(int i=0; i &lt; strLength; i++)
 if(!Character.isWhitespace(pString.charAt(i)))
 return false;
 return false;
}
</code></pre>

blocks|key|122716|text|我之所以回答这个问题，是因为这是谷歌搜索"String+isBlank()+Method“的最高结果。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|122717|如果您使用的是Java11或更高版本，则可以使用String+class+isBlank()方法。这个方法和Apache+Commons的StringUtils类做同样的事情。|offset|length|122718|我已经写了一篇关于这个方法例子的小文章，阅读它here。|122719|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.oracle.com/en/java/javase/12/docs/api/java.base/java/lang/String.html#isBlank()|1|https://www.javastring.net/java/string/java-string-isblank-method-examples^0|0|O|M|0|0|N|4|1|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|S|8|@]|9|@$D|T|E|U|1|V]]|A|$]]|$1|F|3|G|5|6|7|W|8|@]|9|@$D|X|E|Y|1|Z]]|A|$]]|$1|H|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]|P|$5|K|L|M|A|$N|Q]]]]

I am answering this because it's the top result in Google for "String isBlank() Method".

If you are using Java 11 or above, you can use the <a href="https://docs.oracle.com/en/java/javase/12/docs/api/java.base/java/lang/String.html#isBlank()" rel="nofollow noreferrer">String class isBlank()</a> method. This method does the same thing as Apache Commons StringUtils class.

I have written a small post on this method examples, read it <a href="https://www.javastring.net/java/string/java-string-isblank-method-examples" rel="nofollow noreferrer">here</a>.

I ran into some code that has the following: 

<pre><code>String foo = getvalue("foo");
if (StringUtils.isBlank(foo))
 doStuff();
else
 doOtherStuff();
</code></pre>

This appears to be functionally equivalent to the following:

<pre><code>String foo = getvalue("foo");
if (foo.isEmpty())
 doStuff();
else
 doOtherStuff();
</code></pre>

Is a difference between the two (<code>org.apache.commons.lang3.StringUtils.isBlank</code> and <code>java.lang.String.isEmpty</code>)?

StringUtils.isBlank() vs String.isEmpty()

我遇到了一些代码，其中包含以下内容：String foo = getvalue("foo");if (StringUtils.isBlank(foo))    doStuff();else    doOtherStuff();这似乎在功能上等同于以下内容：String foo = getvalue("foo");if (foo.isEmpty())    doStuff();else    doO

问StringUtils.isBlank() vs String.isEmpty()
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