entityMap|blocks|key|39mda|text|它不起作用，因为字符串是不可变的，你需要设置一个值，例如|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5s2f1|line[i]+=+line[i].toLowerCase();|code-block|syntax|js^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

It doesn't work because strings are immutable, you need to set a value
e.g.

<pre><code>line[i] = line[i].toLowerCase(); 
</code></pre>

entityMap|blocks|key|7ulj7|text|您必须重新分配toLowerCase()和replaceAll()返回到line[i]，因为JavaString是不可变的(它的内部值永远不会改变，String类将返回一个新的String|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3tted|对象，而不是修改String对象)。^0|7|D|L|C|10|7|1E|6|22|6|2G|6|0|8|6^^$0|$]|1|@$2|3|4|5|6|7|8|I|9|@$A|J|B|K|C|D]|$A|L|B|M|C|D]|$A|N|B|O|C|D]|$A|P|B|Q|C|D]|$A|R|B|S|C|D]|$A|T|B|U|C|D]]|E|@]|F|$]]|$2|G|4|H|6|7|8|V|9|@$A|W|B|X|C|D]]|E|@]|F|$]]]]

You must reassign the result of <code>toLowerCase()</code> and <code>replaceAll()</code> back to <code>line[i]</code>, since Java <code>String</code> is immutable (its internal value never changes, and the methods in <code>String</code> class will return a new <code>String</code> object instead of modifying the <code>String</code> object).

entityMap|0|type|LINK|mutability|MUTABLE|data|url|https://stackoverflow.com/questions/279507/what-is-meant-by-immutable|blocks|key|f2nb4|text|问题是您的更改没有被存储，因为字符串immutable..。每一个|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|27rvm|方法calls(http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/String.html#replaceAll)+[返回一个新的String表示更改，并使用当前String保持不变。您只需要存储返回的String回到数组中。|style|CODE|alauo|line[i]+=+line[i].replaceAll("[%5Ea-zA-Z]",+"");
line[i]+=+line[i].toLowerCase();|code-block|syntax|javascript|e5kgr|因为each方法返回一个String您可以将您的方法调用链接在一起。这将对第一个方法的结果执行第二个方法调用，允许您在一行中执行这两个操作。|9lflj|line[i]+=+line[i].replaceAll("[%5Ea-zA-Z]",+"").toLowerCase();|js^0|I|9|0|0|2M|6|32|6|3M|6|0|0|C|6|0^^$0|$1|$2|3|4|5|6|$7|8]]]|9|@$A|B|C|D|2|E|F|Y|G|@]|H|@$I|Z|J|10|A|11]]|6|$]]|$A|K|C|L|2|E|F|12|G|@$I|13|J|14|M|N]|$I|15|J|16|M|N]|$I|17|J|18|M|N]]|H|@]|6|$]]|$A|O|C|P|2|Q|F|19|G|@]|H|@]|6|$R|S]]|$A|T|C|U|2|E|F|1A|G|@$I|1B|J|1C|M|N]]|H|@]|6|$]]|$A|V|C|W|2|Q|F|1D|G|@]|H|@]|6|$R|X]]]]

The problem is your changes are not being stored because Strings are <a href="https://stackoverflow.com/questions/279507/what-is-meant-by-immutable">immutable</a>. Each of the <a href="http://docs.oracle.com/javase/1.4.2/docs/api/java/lang/String.html#replaceAll" rel="noreferrer">method calls</a> is returning a new <code>String</code> representing the change, with the current <code>String</code> staying the same. You just need to store the returned <code>String</code> back into the array.

<pre><code>line[i] = line[i].replaceAll("[^a-zA-Z]", "");
line[i] = line[i].toLowerCase();
</code></pre>

Because the each method is returning a <code>String</code> you can chain your method calls together. This will perform the second method call on the result of the first, allowing you to do both actions in one line.

<pre><code>line[i] = line[i].replaceAll("[^a-zA-Z]", "").toLowerCase();
</code></pre>

entityMap|blocks|key|85vd9|text|您需要将正则表达式的结果分配回各行我..。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|efpl4|for+(+int+i+=+0;+i+<+line.length;+i%2B%2B)+{
++line[i]+=+line[i].replaceAll("[%5Ea-zA-Z]",+"").toLowerCase();
}|code-block|syntax|javascript^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

You need to assign the result of your regex back to lines[i].

<pre><code>for ( int i = 0; i &lt; line.length; i++) {
 line[i] = line[i].replaceAll("[^a-zA-Z]", "").toLowerCase();
}
</code></pre>

entityMap|blocks|key|1mbn5|text|一种很酷(但有点麻烦，如果您不喜欢强制转换)的方法是逐个索引遍历整个字符串，将每个结果从String.charAt(索引)转换为(+byte+)，然后检查该字节是否为小写字母字符数值范围(a+=+97到z=+122)中的a)，在这种情况下，将其转换回char并将其添加到字符串、数组或您所拥有的内容的数值范围中，或者b)在数值范围a=97到z=122中在这种情况下，添加32+(A+%2B+22+=+65+%2B+32+=+97+=+a)并将其转换为char并将其相加。如果它不在这两个范围内，只需丢弃它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data^0^^$0|$]|1|@$2|3|4|5|6|7|8|C|9|@]|A|@]|B|$]]]]

A cool (but slightly cumbersome, if you don't like casting) way of doing what you want to do is go through the entire string, index by index, casting each result from String.charAt(index) to (byte), and then checking to see if that byte is either a) in the numeric range of lower-case alphabetic characters (a = 97 to z = 122), in which case cast it back to char and add it to a String, array, or what-have-you, or b) in the numeric range of upper-case alphabetic characters (A = 65 to Z = 90), in which case add 32 (A + 22 = 65 + 32 = 97 = a) and cast that to char and add it in. If it is in neither of those ranges, simply discard it.

entityMap|blocks|key|fbv90|text|因为它已经回答了，只是想分享另一种方式，这里没有提到>|type|unstyled|depth|inlineStyleRanges|entityRanges|data|7cm1u|str+=+str.replaceAll("\\P{Alnum}",+"").toLowerCase();|code-block|syntax|js^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

As it already answered , just thought of sharing one more way that was not mentioned here >

<pre><code> str = str.replaceAll("\\P{Alnum}", "").toLowerCase();
</code></pre>

entityMap|blocks|key|ctbmn|text|您还可以使用Arrays.setAll为此：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|feidh|Arrays.setAll(array,+i+->+array[i].replaceAll("[%5Ea-zA-Z]",+"").toLowerCase());|code-block|syntax|js^0|6|D|0^^$0|$]|1|@$2|3|4|5|6|7|8|L|9|@$A|M|B|N|C|D]]|E|@]|F|$]]|$2|G|4|H|6|I|8|O|9|@]|E|@]|F|$J|K]]]]

You can also use <a href="https://docs.oracle.com/javase/10/docs/api/java/util/Arrays.html#setAll(T%5B%5D,java.util.function.IntFunction)" rel="nofollow noreferrer"><code>Arrays.setAll</code></a> for this:

<pre><code>Arrays.setAll(array, i -&gt; array[i].replaceAll("[^a-zA-Z]", "").toLowerCase());
</code></pre>

entityMap|blocks|key|5s75r|text|以下是工作方法|type|unstyled|depth|inlineStyleRanges|entityRanges|data|8oegk|String+name+=+"Joy.78@,%2B~'{/>";
+String[]+stringArray+=+name.split("\\W%2B");
+StringBuilder+result+=+new+StringBuilder();
+++for+(int+i+=+0;+i+<+stringArray.length;+i%2B%2B)+{
++++result.append(stringArray[i]);
+++}
+++String+nameNew+=+result.toString();
++++nameNew.toLowerCase();|code-block|syntax|javascript^0|0^^$0|$]|1|@$2|3|4|5|6|7|8|H|9|@]|A|@]|B|$]]|$2|C|4|D|6|E|8|I|9|@]|A|@]|B|$F|G]]]]

Here is working method

<pre><code> String name = "Joy.78@,+~'{/&gt;";
 String[] stringArray = name.split("\\W+");
 StringBuilder result = new StringBuilder();
 for (int i = 0; i &lt; stringArray.length; i++) {
 result.append(stringArray[i]);
 }
 String nameNew = result.toString();
 nameNew.toLowerCase();
</code></pre>

I'm trying to write a method that removes all non alphabetic characters from a Java <code>String[]</code> and then convert the String to an lower case string. I've tried using regular expression to replace the occurence of all non alphabetic characters by <code>""</code> .However, the output that I am getting is not able to do so. Here is the code

<pre><code>static String[] inputValidator(String[] line) {
 for(int i = 0; i &lt; line.length; i++) {
 line[i].replaceAll("[^a-zA-Z]", "");
 line[i].toLowerCase();
 }
 return line;
}
</code></pre>

However if I try to supply an input that has non alphabets (say <code>-</code> or <code>.</code>) the output also consists of them, as they are not removed.

Example Input

<pre><code>A dog is an animal. Animals are not people.
</code></pre>

Output that I'm getting

<pre><code>A
dog
is
an
animal.
Animals
are
not
people.
</code></pre>

Output that is expected

<pre><code>a
dog
is
an
animal
animals
are
not
people
</code></pre>

Remove all non alphabetic characters from a String array in java

Java

 我正在尝试编写一个方法，该方法可以从Java中删除所有非字母字符String[]然后将字符串转换为小写字符串。我尝试使用正则表达式将所有非字母字符的出现替换为"".However，我得到的输出不能这样做。以下是代码 static String[] inputValidator(String[] line) {    ...

问从java中的字符串数组中删除所有非字母字符
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