blocks|key|943764|text|你可以用java.nio.charset.Charset做到这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|943765|import+java.nio.charset.Charset;

public+class+StringUtils+{

++public+static+boolean+isPureAscii(String+v)+{
++++return+Charset.forName("US-ASCII").newEncoder().canEncode(v);
++++//+or+"ISO-8859-1"+for+ISO+Latin+1
++++//+or+StandardCharsets.US_ASCII+with+JDK1.7%2B
++}

++public+static+void+main+(String+args[])
++++throws+Exception+{

+++++String+test+=+"Réal";
+++++System.out.println(test+%2B+"+isPureAscii()+:+"+%2B+StringUtils.isPureAscii(test));
+++++test+=+"Real";
+++++System.out.println(test+%2B+"+isPureAscii()+:+"+%2B+StringUtils.isPureAscii(test));

+++++/*
++++++*+output+:
++++++*+++Réal+isPureAscii()+:+false
++++++*+++Real+isPureAscii()+:+true
++++++*/
++}
}|code-block|syntax|javascript|943766|Detect+non-ASCII+character+in+a+String|943767|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/1.5.0/docs/api/java/nio/charset/Charset.html|1|http://www.rgagnon.com/javadetails/java-0536.html^0|4|O|0|0|0|0|12|1|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@$A|10|B|11|1|12]]|C|$]]|$1|K|3|-4|5|6|7|13|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]|S|$5|N|O|P|C|$Q|T]]]]

You can do it with <a href="http://download.oracle.com/javase/1.5.0/docs/api/java/nio/charset/Charset.html" rel="noreferrer">java.nio.charset.Charset</a>.

<pre><code>import java.nio.charset.Charset;

public class StringUtils {

 public static boolean isPureAscii(String v) {
 return Charset.forName("US-ASCII").newEncoder().canEncode(v);
 // or "ISO-8859-1" for ISO Latin 1
 // or StandardCharsets.US_ASCII with JDK1.7+
 }

 public static void main (String args[])
 throws Exception {

 String test = "Réal";
 System.out.println(test + " isPureAscii() : " + StringUtils.isPureAscii(test));
 test = "Real";
 System.out.println(test + " isPureAscii() : " + StringUtils.isPureAscii(test));

 /*
 * output :
 * Réal isPureAscii() : false
 * Real isPureAscii() : true
 */
 }
}
</code></pre>

<a href="http://www.rgagnon.com/javadetails/java-0536.html" rel="noreferrer">Detect non-ASCII character in a String</a>

blocks|key|943818|text|这是另一种不依赖于库，而是使用正则表达式的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|943819|您可以使用这一行：|943820|text.matches("\\A\\p{ASCII}*\\z")|code-block|syntax|javascript|943821|整个示例程序：|943822|public+class+Main+{
++++public+static+void+main(String[]+args)+{
++++++++char+nonAscii+=+0x00FF;
++++++++String+asciiText+=+"Hello";
++++++++String+nonAsciiText+=+"Buy:+"+%2B+nonAscii;
++++++++System.out.println(asciiText.matches("\\A\\p{ASCII}*\\z"));
++++++++System.out.println(nonAsciiText.matches("\\A\\p{ASCII}*\\z"));
++++}
}|943823|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|$]]

Here is another way not depending on a library but using a regex.

You can use this single line:

<pre><code>text.matches("\\A\\p{ASCII}*\\z")
</code></pre>

Whole example program:

<pre><code>public class Main {
 public static void main(String[] args) {
 char nonAscii = 0x00FF;
 String asciiText = "Hello";
 String nonAsciiText = "Buy: " + nonAscii;
 System.out.println(asciiText.matches("\\A\\p{ASCII}*\\z"));
 System.out.println(nonAsciiText.matches("\\A\\p{ASCII}*\\z"));
 }
}
</code></pre>

blocks|key|1157981|text|遍历字符串并确保所有字符的值都小于128。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1157982|Java字符串在概念上编码为UTF-16。在UTF-16中，ASCII字符集被编码为值0-+127，并且保证任何非ASCII字符(可能由多个Java字符组成)的编码不包括数字0-+127|1157983|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|$]]

Iterate through the string and make sure all the characters have a value less than 128.

Java Strings are conceptually encoded as UTF-16. In UTF-16, the ASCII character set is encoded as the values 0 - 127 and the encoding for any non ASCII character (which may consist of more than one Java char) is guaranteed not to include the numbers 0 - 127

blocks|key|1157997|text|或者从IDN类复制代码。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1157998|//+to+check+if+a+string+only+contains+US-ASCII+code+point
//
private+static+boolean+isAllASCII(String+input)+{
++++boolean+isASCII+=+true;
++++for+(int+i+=+0;+i+<+input.length();+i%2B%2B)+{
++++++++int+c+=+input.charAt(i);
++++++++if+(c+>+0x7F)+{
++++++++++++isASCII+=+false;
++++++++++++break;
++++++++}
++++}
++++return+isASCII;
}|code-block|syntax|javascript|1157999|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/6/docs/api/java/net/IDN.html^0|3|3|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]]]]

Or you copy the code from the <a href="http://docs.oracle.com/javase/6/docs/api/java/net/IDN.html" rel="noreferrer">IDN</a> class.

<pre><code>// to check if a string only contains US-ASCII code point
//
private static boolean isAllASCII(String input) {
 boolean isASCII = true;
 for (int i = 0; i &lt; input.length(); i++) {
 int c = input.charAt(i);
 if (c &gt; 0x7F) {
 isASCII = false;
 break;
 }
 }
 return isASCII;
}
</code></pre>

blocks|key|943961|text|Apache的commons-lang3包含有价值的实用/方便的方法来解决所有类型的“问题”，包括这个问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|943962|System.out.println(StringUtils.isAsciiPrintable("!@£$%25%5E&!@£$%25%5E"));|code-block|syntax|javascript|943963|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|$]]

commons-lang3 from Apache contains valuable utility/convenience methods for all kinds of 'problems', including this one. 

<pre><code>System.out.println(StringUtils.isAsciiPrintable("!@£$%^&amp;!@£$%^"));
</code></pre>

blocks|key|943912|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|943913|for+(char+c:+string.toCharArray()){
++if+(((int)c)>127){
++++return+false;
++}+
}
return+true;|code-block|syntax|javascript|943914|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|$]]

try this:

<pre><code>for (char c: string.toCharArray()){
 if (((int)c)&gt;127){
 return false;
 } 
}
return true;
</code></pre>

blocks|key|1158094|text|如果字符串仅包含ASCII字符，则返回true；如果不包含ASCII字符，则返回false|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1158095|Charset.forName("US-ASCII").newEncoder().canEncode(str)|code-block|syntax|javascript|1158096|如果您想删除非ASCII，下面是代码片段：|1158097|if(!Charset.forName("US-ASCII").newEncoder().canEncode(str))+{
++++++++++++++++++++++++str+=+str.replaceAll("[%5E\\p{ASCII}]",+"");
++++++++++++++++++++}|1158098|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

This will return true if String only contains ASCII characters and false when it does not 

<pre><code>Charset.forName("US-ASCII").newEncoder().canEncode(str)
</code></pre>

If You want to remove non ASCII , here is the snippet:

<pre><code>if(!Charset.forName("US-ASCII").newEncoder().canEncode(str)) {
 str = str.replaceAll("[^\\p{ASCII}]", "");
 }
</code></pre>

blocks|key|944045|text|在Kotlin：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|944046|fun+String.isAsciiString()+:+Boolean+=
++++this.toCharArray().none+{+it+<+'+'+%7C%7C+it+>+'~'+}|code-block|syntax|javascript|944047|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|$]]

In Kotlin:
<pre><code>fun String.isAsciiString() : Boolean =
 this.toCharArray().none { it &lt; ' ' || it &gt; '~' }
</code></pre>

blocks|key|1157862|text|遍历字符串，并使用charAt()获得字符。然后将其视为int，并查看它是否具有您喜欢的Unicode值(ASCII的超集)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1157863|在你不喜欢的第一个地方休息。|1157864|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|$]]

Iterate through the string, and use charAt() to get the char. Then treat it as an int, and see if it has a unicode value (a superset of ASCII) which you like.

Break at the first you don't like.

blocks|key|1158080|text|private+static+boolean+isASCII(String+s)+
{
++++for+(int+i+=+0;+i+<+s.length();+i%2B%2B)+
++++++++if+(s.charAt(i)+>+127)+
++++++++++++return+false;
++++return+true;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1158081|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>private static boolean isASCII(String s) 
{
 for (int i = 0; i &lt; s.length(); i++) 
 if (s.charAt(i) &gt; 127) 
 return false;
 return true;
}
</code></pre>

blocks|key|943921|text|这是可能的。真是个大问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|943922|import+java.io.UnsupportedEncodingException;
import+java.nio.charset.Charset;
import+java.nio.charset.CharsetEncoder;

public+class+EncodingTest+{

++++static+CharsetEncoder+asciiEncoder+=+Charset.forName("US-ASCII")
++++++++++++.newEncoder();

++++public+static+void+main(String[]+args)+{

++++++++String+testStr+=+"¤EÀsÆW°ê»Ú®i¶T¤¤¤ß3¼Ó®i¶TÆU2~~KITEC+3/F+Rotunda+2";
++++++++String[]+strArr+=+testStr.split("~~",+2);
++++++++int+count+=+0;
++++++++boolean+encodeFlag+=+false;

++++++++do+{
++++++++++++encodeFlag+=+asciiEncoderTest(strArr[count]);
++++++++++++System.out.println(encodeFlag);
++++++++++++count%2B%2B;
++++++++}+while+(count+<+strArr.length);
++++}

++++public+static+boolean+asciiEncoderTest(String+test)+{
++++++++boolean+encodeFlag+=+false;
++++++++try+{
++++++++++++encodeFlag+=+asciiEncoder.canEncode(new+String(test
++++++++++++++++++++.getBytes("ISO8859_1"),+"BIG5"));
++++++++}+catch+(UnsupportedEncodingException+e)+{
++++++++++++e.printStackTrace();
++++++++}
++++++++return+encodeFlag;
++++}
}|code-block|syntax|javascript|943923|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|$]]

It was possible. Pretty problem.

<pre><code>import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;

public class EncodingTest {

 static CharsetEncoder asciiEncoder = Charset.forName("US-ASCII")
 .newEncoder();

 public static void main(String[] args) {

 String testStr = "¤EÀsÆW°ê»Ú®i¶T¤¤¤ß3¼Ó®i¶TÆU2~~KITEC 3/F Rotunda 2";
 String[] strArr = testStr.split("~~", 2);
 int count = 0;
 boolean encodeFlag = false;

 do {
 encodeFlag = asciiEncoderTest(strArr[count]);
 System.out.println(encodeFlag);
 count++;
 } while (count &lt; strArr.length);
 }

 public static boolean asciiEncoderTest(String test) {
 boolean encodeFlag = false;
 try {
 encodeFlag = asciiEncoder.canEncode(new String(test
 .getBytes("ISO8859_1"), "BIG5"));
 } catch (UnsupportedEncodingException e) {
 e.printStackTrace();
 }
 return encodeFlag;
 }
}
</code></pre>

blocks|key|1158128|text|在Java8及更高版本中，可以将String#codePoints与IntStream#allMatch结合使用。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1158129|boolean+allASCII+=+str.codePoints().allMatch(c+->+c+<+128);|code-block|syntax|javascript|1158130|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.oracle.com/javase/8/docs/api/java/lang/CharSequence.html#codePoints--|1|https://docs.oracle.com/javase/8/docs/api/java/util/stream/IntStream.html#allMatch-java.util.function.IntPredicate-^0|G|H|Y|I|G|H|0|Y|I|1|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]|$9|12|A|13|1|14]]|E|$]]|$1|F|3|G|5|H|7|15|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]|S|$5|N|O|P|E|$Q|T]]]]

In Java 8 and above, one can use <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/CharSequence.html#codePoints--" rel="nofollow noreferrer"><code>String#codePoints</code></a> in conjunction with <a href="https://docs.oracle.com/javase/8/docs/api/java/util/stream/IntStream.html#allMatch-java.util.function.IntPredicate-" rel="nofollow noreferrer"><code>IntStream#allMatch</code></a>.
<pre><code>boolean allASCII = str.codePoints().allMatch(c -&gt; c &lt; 128);
</code></pre>

blocks|key|1158037|text|//return+is+uppercase+or+lowercase
public+boolean+isASCIILetter(char+c)+{
++return+(c+>+64+&&+c+<+91)+%7C%7C+(c+>+96+&&+c+<+123);
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1158038|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>//return is uppercase or lowercase
public boolean isASCIILetter(char c) {
 return (c &gt; 64 &amp;&amp; c &lt; 91) || (c &gt; 96 &amp;&amp; c &lt; 123);
}
</code></pre>

The call <code>Character.isLetter(c)</code> returns <code>true</code> if the character is a letter. But is there a way to quickly find if a <code>String</code> only contains the base characters of ASCII?

How to check if a String contains only ASCII?

Kotlin

Java

如果字符是字母，则调用Character.isLetter(c)返回true。但是，有没有一种方法可以快速发现String是否只包含ASCII码的基本字符？

问如何检查字符串是否只包含ASCII？
EN

回答 13

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问如何检查字符串是否只包含ASCII？EN

回答 13

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问如何检查字符串是否只包含ASCII？
EN