blocks|key|2701924|text|我不记得在标准JDK中有这样的函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2701925|如果你想自动检测样式，你可以用switch-case或Strategy+pattern编写辅助函数。|offset|length|style|CODE|2701926|首先，检查数字字符串是否以0x开头，如果不是，则检查它是否以0开头。但是如果你有二进制数，这是行不通的。但在你的问题%5E_%5E中没有这样的东西。|2701927|请参见Integer.parse(String+s,+radix)方法。|2701928|2701929|附加示例代码：|2701930|public+class+RadixDetector+{

++++private+static+final+int+RADIX_HEX+=+16;
++++private+static+final+int+RADIX_OCTAL+=+8;

++++public+static+int+detectRadix(String+number)+{

++++++++if+(number.toLowerCase().startsWith("0x")+&&+isValidHex(number))+{
++++++++++++return+RADIX_HEX;
++++++++}+else+if+(number.startsWith("0")+&&+isValidOctal(number))+{
++++++++++++return+RADIX_OCTAL;
++++++++}+else+{
++++++++++++throw+new+NumberFormatException("Unknown+or+unable+to+detect+radix+for:+"+%2B+number);
++++++++}
++++}

++++public+static+boolean+isValidHex(String+number)+{
++++++++Pattern+hexPattern+=+Pattern.compile("0[xX][0-9a-fA-F]%2B");
++++++++return+hexPattern.matcher(number).matches();
++++}

++++public+static+boolean+isValidOctal(String+number)+{
++++++++Pattern+hexPattern+=+Pattern.compile("0[1-7][0-7]*");
++++++++return+hexPattern.matcher(number).matches();
++++}
}|code-block|syntax|javascript|2701931|和测试：|2701932|public+class+NumberRadixTests+{

++++@Test
++++public+void+testRadixDetection()+{
++++++++assertEquals(16,+RadixDetector.detectRadix("0xabcd"));
++++++++assertEquals(16,+RadixDetector.detectRadix("0xABCD"));
++++++++assertEquals(16,+RadixDetector.detectRadix("0xAFFF"));
++++++++assertEquals(16,+RadixDetector.detectRadix("0x0"));
++++++++assertEquals(16,+RadixDetector.detectRadix("0X0"));
++++++++assertEquals(16,+RadixDetector.detectRadix("0XFFF"));
++++++++assertEquals(8,+RadixDetector.detectRadix("0123"));
++++++++assertEquals(8,+RadixDetector.detectRadix("011"));
++++++++assertEquals(8,+RadixDetector.detectRadix("0777"));
++++++++assertEquals(8,+RadixDetector.detectRadix("0666"));
++++}

++++@Test
++++public+void+testHexRegex()+{
++++++++assertTrue(RadixDetector.isValidHex("0xabcd"));
++++++++assertTrue(RadixDetector.isValidHex("0Xabcd"));
++++++++assertTrue(RadixDetector.isValidHex("0xAbcd"));
++++++++assertTrue(RadixDetector.isValidHex("0xa0cd"));
++++++++assertTrue(RadixDetector.isValidHex("0x9bc1"));
++++++++assertTrue(RadixDetector.isValidHex("0x9bc1"));
++++++++assertFalse(RadixDetector.isValidHex("x9bc1"));
++++++++assertFalse(RadixDetector.isValidHex("0xbtc1"));
++++++++assertFalse(RadixDetector.isValidHex("0xx9bc1"));
++++++++assertFalse(RadixDetector.isValidHex("00x9bc1"));
++++++++assertFalse(RadixDetector.isValidHex("0x9pc1"));
++++++++assertFalse(RadixDetector.isValidHex("0x"));
++++++++assertFalse(RadixDetector.isValidHex("077"));
++++}

++++@Test
++++public+void+testOctalRegex()+{
++++++++assertTrue(RadixDetector.isValidOctal("077"));
++++++++assertTrue(RadixDetector.isValidOctal("067"));
++++++++assertTrue(RadixDetector.isValidOctal("07777"));
++++++++assertTrue(RadixDetector.isValidOctal("017"));
++++++++assertFalse(RadixDetector.isValidOctal("08"));
++++++++assertFalse(RadixDetector.isValidOctal("8"));
++++++++assertFalse(RadixDetector.isValidOctal("777"));
++++++++assertFalse(RadixDetector.isValidOctal("0x"));
++++++++assertFalse(RadixDetector.isValidOctal("08"));
++++++++assertFalse(RadixDetector.isValidOctal("01238"));
++++}

}|2701933|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#parseInt(java.lang.String,%2520int)^0|0|F|B|R|G|0|D|2|U|1|0|3|U|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|16|8|@$D|17|E|18|F|G]|$D|19|E|1A|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|1B|8|@$D|1C|E|1D|F|G]|$D|1E|E|1F|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|1G|8|@]|9|@$D|1H|E|1I|1|1J]]|A|$]]|$1|L|3|-4|5|6|7|1K|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|1L|8|@]|9|@]|A|$]]|$1|O|3|P|5|Q|7|1M|8|@]|9|@]|A|$R|S]]|$1|T|3|U|5|6|7|1N|8|@]|9|@]|A|$]]|$1|V|3|W|5|Q|7|1O|8|@]|9|@]|A|$R|S]]|$1|X|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]]|Y|$Z|$5|10|11|12|A|$13|14]]]]

I can't remember such function in standard JDK.

If you want to auto detect style, you cat write helper function with <code>switch-case</code> or <code>Strategy pattern</code>.

First, check if number string starts with <code>0x</code>, if no - check if it starts with <code>0</code> at all. But this won't work if you will have binary number. But there are no such in your question ^_^.

See <a href="https://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#parseInt(java.lang.String,%20int)" rel="nofollow">Integer.parse(String s, radix)</a> method.

<hr>

Attaching sample code:

<pre><code>public class RadixDetector {

 private static final int RADIX_HEX = 16;
 private static final int RADIX_OCTAL = 8;

 public static int detectRadix(String number) {

 if (number.toLowerCase().startsWith("0x") &amp;&amp; isValidHex(number)) {
 return RADIX_HEX;
 } else if (number.startsWith("0") &amp;&amp; isValidOctal(number)) {
 return RADIX_OCTAL;
 } else {
 throw new NumberFormatException("Unknown or unable to detect radix for: " + number);
 }
 }

 public static boolean isValidHex(String number) {
 Pattern hexPattern = Pattern.compile("0[xX][0-9a-fA-F]+");
 return hexPattern.matcher(number).matches();
 }

 public static boolean isValidOctal(String number) {
 Pattern hexPattern = Pattern.compile("0[1-7][0-7]*");
 return hexPattern.matcher(number).matches();
 }
}
</code></pre>

And tests:

<pre><code>public class NumberRadixTests {

 @Test
 public void testRadixDetection() {
 assertEquals(16, RadixDetector.detectRadix("0xabcd"));
 assertEquals(16, RadixDetector.detectRadix("0xABCD"));
 assertEquals(16, RadixDetector.detectRadix("0xAFFF"));
 assertEquals(16, RadixDetector.detectRadix("0x0"));
 assertEquals(16, RadixDetector.detectRadix("0X0"));
 assertEquals(16, RadixDetector.detectRadix("0XFFF"));
 assertEquals(8, RadixDetector.detectRadix("0123"));
 assertEquals(8, RadixDetector.detectRadix("011"));
 assertEquals(8, RadixDetector.detectRadix("0777"));
 assertEquals(8, RadixDetector.detectRadix("0666"));
 }

 @Test
 public void testHexRegex() {
 assertTrue(RadixDetector.isValidHex("0xabcd"));
 assertTrue(RadixDetector.isValidHex("0Xabcd"));
 assertTrue(RadixDetector.isValidHex("0xAbcd"));
 assertTrue(RadixDetector.isValidHex("0xa0cd"));
 assertTrue(RadixDetector.isValidHex("0x9bc1"));
 assertTrue(RadixDetector.isValidHex("0x9bc1"));
 assertFalse(RadixDetector.isValidHex("x9bc1"));
 assertFalse(RadixDetector.isValidHex("0xbtc1"));
 assertFalse(RadixDetector.isValidHex("0xx9bc1"));
 assertFalse(RadixDetector.isValidHex("00x9bc1"));
 assertFalse(RadixDetector.isValidHex("0x9pc1"));
 assertFalse(RadixDetector.isValidHex("0x"));
 assertFalse(RadixDetector.isValidHex("077"));
 }

 @Test
 public void testOctalRegex() {
 assertTrue(RadixDetector.isValidOctal("077"));
 assertTrue(RadixDetector.isValidOctal("067"));
 assertTrue(RadixDetector.isValidOctal("07777"));
 assertTrue(RadixDetector.isValidOctal("017"));
 assertFalse(RadixDetector.isValidOctal("08"));
 assertFalse(RadixDetector.isValidOctal("8"));
 assertFalse(RadixDetector.isValidOctal("777"));
 assertFalse(RadixDetector.isValidOctal("0x"));
 assertFalse(RadixDetector.isValidOctal("08"));
 assertFalse(RadixDetector.isValidOctal("01238"));
 }

}
</code></pre>

This one is short, but I can't find the answer anywhere.

Is there a jdk routine that can parse a <code>String</code> to an <code>int</code>, and autodetect and convert C-style programming conventions:

<ul>
<li>123 (decimal)</li>
<li>0x1ABC (hex)</li>
<li>0x1abc (hex)</li>
<li>0777 (octal)</li>
</ul>

Thanks!

EDIT: 

Let me be clear here, I know I can handroll this method. I already did so! I know what a radix is and about <code>Integer.parse(..., radix)</code>! What I am asking is, hasn't the JDK already got a method that handles all the cases. A one-liner for the whole lot...

Parse a C-style programmer's integer in Java

这个问题很短，但我到处都找不到答案。是否有一个jdk例程可以将String解析为int，并自动检测和转换C风格的编程约定：123 (decimal)0x1ABC (十六进制)0x1abc(十六进制)0777(八进制)谢谢!编辑：让我在这里说清楚，我知道我可以处理这个方法。我已经这么做了！我知道基数是什么，也知道Inte...

问在Java中解析C风格程序员的整数
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