blocks|key|855010|text|根据How+to+convert+Strings+to+and+from+UTF8+byte+arrays+in+Java的说法|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|855011|String+s+=+"some+text+here";
byte[]+b+=+s.getBytes("UTF-8");
System.out.println(b.length);|code-block|syntax|javascript|855012|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/88838/how-to-convert-strings-to-and-from-utf8-byte-arrays-in-java/88863#88863^0|2|1N|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

According to <a href="https://stackoverflow.com/questions/88838/how-to-convert-strings-to-and-from-utf8-byte-arrays-in-java/88863#88863">How to convert Strings to and from UTF8 byte arrays in Java</a>:

<pre><code>String s = "some text here";
byte[] b = s.getBytes("UTF-8");
System.out.println(b.length);
</code></pre>

blocks|key|1069475|text|有一个叫做getBytes()的方法。明智地使用它。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1069476|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/6/docs/api/java/lang/String.html#getBytes%2528%2529^0|5|A|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

There's a method called <a href="http://download.oracle.com/javase/6/docs/api/java/lang/String.html#getBytes%28%29" rel="noreferrer">getBytes()</a>. Use it wisely .

blocks|key|855093|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|855094|Bytes.toBytes(x).length|code-block|syntax|javascript|855095|假设您之前声明并初始化了x|855096|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|$]]

Try this :

<pre><code>Bytes.toBytes(x).length
</code></pre>

Assuming you declared and initialized x before

blocks|key|855154|text|String实例在内存中分配一定数量的字节。也许您正在查看类似sizeof("Hello+World")的内容，它将返回数据结构本身分配的字节数？|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|855155|在Java语言中，通常不需要sizeof函数，因为我们从不分配内存来存储数据结构。我们可以查看String.java文件进行粗略估计，我们看到一些“int”、一些引用和一个char[]。Java+language+specification定义char的范围是从0到65535，因此两个字节足以在内存中保留一个字符。但是JVM不必在2个字节中存储一个字符，它只需保证char的实现可以保存定义范围的值。|855156|所以sizeof在Java语言中没有任何意义。但是，假设我们有一个很大的字符串，一个char分配了两个字节，那么String对象的内存占用至少是以字节为单位的2+*+str.length()。|855157|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#4.2.1^0|0|6|V|L|0|E|6|1B|B|2E|6|3E|4|53|4|2L|R|0|0|2|6|16|4|1K|6|27|G|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]|$9|13|A|14|B|C]|$9|15|A|16|B|C]]|D|@$9|17|A|18|1|19]]|E|$]]|$1|H|3|I|5|6|7|1A|8|@$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|J|3|-4|5|6|7|1J|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

A <code>String</code> instance allocates a certain amount of bytes in memory. Maybe you're looking at something like <code>sizeof("Hello World")</code> which would return the number of bytes allocated by the datastructure itself?

In Java, there's usually no need for a <code>sizeof</code> function, because we never allocate memory to store a data structure. We can have a look at the <code>String.java</code> file for a rough estimation, and we see some 'int', some references and a <code>char[]</code>. The <a href="http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#4.2.1" rel="noreferrer">Java language specification</a> defines, that a <code>char</code> ranges from 0 to 65535, so two bytes are sufficient to keep a single char in memory. But a JVM does not have to store one char in 2 bytes, it only has to guarantee, that the implementation of <code>char</code> can hold values of the defines range.

So <code>sizeof</code> really does not make any sense in Java. But, assuming that we have a large String and one <code>char</code> allocates two bytes, then the memory footprint of a <code>String</code> object is at least <code>2 * str.length()</code> in bytes.

blocks|key|855227|text|如果您运行的是64位引用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|855228|sizeof(string)+=+
8+%2B+//+object+header+used+by+the+VM
8+%2B+//+64-bit+reference+to+char+array+(value)
8+%2B+string.length()+*+2+%2B+//+character+array+itself+(object+header+%2B+16-bit+chars)
4+%2B+//+offset+integer
4+%2B+//+count+integer
4+%2B+//+cached+hash+code|code-block|syntax|javascript|855229|换句话说：|855230|sizeof(string)+=+36+%2B+string.length()+*+2|855231|在32位VM或具有压缩OOPs+(-XX:%2BUseCompressedOops)的64位VM上，引用是4字节。因此，总数将是：|855232|sizeof(string)+=+32+%2B+string.length()+*+2|855233|这不考虑对string对象的引用。|855234|entityMap^0|0|0|0|0|0|0|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]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

If you're running with 64-bit references:

<pre><code>sizeof(string) = 
8 + // object header used by the VM
8 + // 64-bit reference to char array (value)
8 + string.length() * 2 + // character array itself (object header + 16-bit chars)
4 + // offset integer
4 + // count integer
4 + // cached hash code
</code></pre>

In other words:

<pre><code>sizeof(string) = 36 + string.length() * 2
</code></pre>

On a 32-bit VM or a 64-bit VM with compressed OOPs (-XX:+UseCompressedOops), the references are 4 bytes. So the total would be:

<pre><code>sizeof(string) = 32 + string.length() * 2
</code></pre>

This does not take into account the references to the string object.

blocks|key|1069655|text|要避免尝试捕获，请使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1069656|String+s+=+"some+text+here";
byte[]+b+=+s.getBytes(StandardCharsets.UTF_8);
System.out.println(b.length);|code-block|syntax|javascript|1069657|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|$]]

To avoid try catch, use:

<pre><code>String s = "some text here";
byte[] b = s.getBytes(StandardCharsets.UTF_8);
System.out.println(b.length);
</code></pre>

blocks|key|855295|text|使用apache+commons尝试一下|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|855296|String+src+=+"Hello";+//This+will+work+with+any+serialisable+object
System.out.println(
++++++++++++"Object+Size:"+%2B+SerializationUtils.serialize((Serializable)+src).length)|code-block|syntax|javascript|855297|entityMap|0|LINK|mutability|MUTABLE|url|https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/SerializationUtils.html^0|2|E|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Try this using <a href="https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/SerializationUtils.html" rel="nofollow noreferrer">apache commons</a>:
<pre><code>String src = &quot;Hello&quot;; //This will work with any serialisable object
System.out.println(
 &quot;Object Size:&quot; + SerializationUtils.serialize((Serializable) src).length)
</code></pre>

In Java, if I have a String <code>x</code>, how can I calculate the number of bytes in that string?

Bytes of a string in Java

数据结构

Java

在Java语言中，如果我有一个字符串x，我如何计算该字符串中的字节数？

问Java中字符串的字节数
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问Java中字符串的字节数EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问Java中字符串的字节数
EN