blocks|key|762260|text|看看String.indexOf和String.substring。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|762261|确保检查-1中是否有indexOf。|762262|entityMap^0|2|E|H|G|0|A|7|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|R|8|@]|D|@]|E|$]]]|I|$]]

look at <code>String.indexOf</code> and <code>String.substring</code>. 

Make sure you check for -1 for <code>indexOf</code>.

blocks|key|762492|text|公认的答案是正确的，但它没有告诉你如何使用它。这就是如何同时使用indexOf和子字符串函数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|762493|String+filename+=+"abc.def.ghi";+++++//+full+file+name
int+iend+=+filename.indexOf(".");+//this+finds+the+first+occurrence+of+"."+
//in+string+thus+giving+you+the+index+of+where+it+is+in+the+string

//+Now+iend+can+be+-1,+if+lets+say+the+string+had+no+"."+at+all+in+it+i.e.+no+"."+is+found.+
//So+check+and+account+for+it.

String+subString;
if+(iend+!=+-1)+
{
++++subString=+filename.substring(0+,+iend);+//this+will+give+abc
}|code-block|syntax|javascript|762494|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 accepted answer is correct but it doesn't tell you how to use it. This is how you use indexOf and substring functions together.

<pre><code>String filename = "abc.def.ghi"; // full file name
int iend = filename.indexOf("."); //this finds the first occurrence of "." 
//in string thus giving you the index of where it is in the string

// Now iend can be -1, if lets say the string had no "." at all in it i.e. no "." is found. 
//So check and account for it.

String subString;
if (iend != -1) 
{
 subString= filename.substring(0 , iend); //this will give abc
}
</code></pre>

blocks|key|545764|text|您可以只对字符串执行split操作。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|545765|public+String[]+split(String+regex)|code-block|syntax|javascript|545766|请注意，java.lang.String.split使用分隔符的正则表达式值。基本上就像这样..。|545767|String+filename+=+"abc.def.ghi";+++++//+full+file+name
String[]+parts+=+filename.split("\\.");+//+String+array,+each+element+is+text+between+dots

String+beforeFirstDot+=+parts[0];++++//+Text+before+the+first+dot|545768|当然，为了清晰起见，这被分成了多行。它可以写成|545769|String+beforeFirstDot+=+filename.split("\\.")[0];|545770|entityMap|0|LINK|mutability|MUTABLE|url|http://download.oracle.com/javase/1.4.2/docs/api/java/lang/String.html#split%2528java.lang.String%2529^0|A|5|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@$A|Z|B|10|1|11]]|C|$]]|$1|D|3|E|5|F|7|12|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|13|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|14|8|@]|9|@]|C|$G|H]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|C|$]]|$1|O|3|P|5|F|7|16|8|@]|9|@]|C|$G|H]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|C|$]]]|R|$S|$5|T|U|V|C|$W|X]]]]

You can just <a href="http://download.oracle.com/javase/1.4.2/docs/api/java/lang/String.html#split%28java.lang.String%29" rel="noreferrer">split</a> the string..

<pre><code>public String[] split(String regex)
</code></pre>

Note that java.lang.String.split uses delimiter's regular expression value.
Basically like this...

<pre><code>String filename = "abc.def.ghi"; // full file name
String[] parts = filename.split("\\."); // String array, each element is text between dots

String beforeFirstDot = parts[0]; // Text before the first dot
</code></pre>

Of course, this is split into multiple lines for clairity. It could be written as

<pre><code>String beforeFirstDot = filename.split("\\.")[0];
</code></pre>

blocks|key|762437|text|如果您项目已经使用了commons-lang，StringUtils为此提供了一个很好的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|762438|String+filename+=+"abc.def.ghi";

String+start+=+StringUtils.substringBefore(filename,+".");+//+returns+"abc"|code-block|syntax|javascript|762439|请参阅javadoc+[2.6]+[3.1]|762440|entityMap|0|LINK|mutability|MUTABLE|url|http://commons.apache.org/proper/commons-lang/|1|http://commons.apache.org/proper/commons-lang/javadocs/api-2.6/org/apache/commons/lang/StringUtils.html#substringBefore%2528java.lang.String,%2520java.lang.String%2529|2|http://commons.apache.org/proper/commons-lang/javadocs/api-3.1/org/apache/commons/lang3/StringUtils.html#substringBefore%2528java.lang.String,%2520java.lang.String%2529^0|A|C|0|0|0|B|5|1|H|5|2|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|11|8|@]|9|@$A|12|B|13|1|14]|$A|15|B|16|1|17]]|C|$]]|$1|K|3|-4|5|6|7|18|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]|S|$5|N|O|P|C|$Q|T]]|U|$5|N|O|P|C|$Q|V]]]]

If your project already uses <a href="http://commons.apache.org/proper/commons-lang/">commons-lang</a>, StringUtils provide a nice method for this purpose:

<pre><code>String filename = "abc.def.ghi";

String start = StringUtils.substringBefore(filename, "."); // returns "abc"
</code></pre>

see javadoc <a href="http://commons.apache.org/proper/commons-lang/javadocs/api-2.6/org/apache/commons/lang/StringUtils.html#substringBefore%28java.lang.String,%20java.lang.String%29">[2.6]</a> <a href="http://commons.apache.org/proper/commons-lang/javadocs/api-3.1/org/apache/commons/lang3/StringUtils.html#substringBefore%28java.lang.String,%20java.lang.String%29">[3.1]</a>

blocks|key|545664|text|或者你可以尝试像这样的东西|type|unstyled|depth|inlineStyleRanges|entityRanges|data|545665|"abc.def.ghi".substring(0,"abc.def.ghi".indexOf(c)-1);|offset|length|style|CODE|545666|entityMap^0|0|0|1I|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

or you may try something like

<code>"abc.def.ghi".substring(0,"abc.def.ghi".indexOf(c)-1);</code>

blocks|key|762340|text|使用正则表达式怎么样？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|762341|String+firstWord+=+filename.replaceAll("\\..*","")|code-block|syntax|javascript|762342|这会用"“替换从第一个点到最后的所有内容(即清除它，留下你想要的东西)|762343|下面是一个测试：|762344|System.out.println("abc.def.hij".replaceAll("\\..*",+"");|762345|输出：|762346|abc|762347|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]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|W|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

How about using regex?

<pre><code>String firstWord = filename.replaceAll("\\..*","")
</code></pre>

This replaces everything from the first dot to the end with "" (ie it clears it, leaving you with what you want)

Here's a test:

<pre><code>System.out.println("abc.def.hij".replaceAll("\\..*", "");
</code></pre>

Output:

<pre><code>abc
</code></pre>

blocks|key|545889|text|下面的代码从String返回一个子字符串，直到给定的字符列表中的任何一个：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|545890|/**
+*+Return+a+substring+of+the+given+original+string+until+the+first+appearance
+*+of+any+of+the+given+characters.
+*+
+*+e.g.+Original+"ab&cd-ef&gh"
+*+1.+Separators+{'&',+'-'}
+*+Result:+"ab"
+*+2.+Separators+{'~',+'-'}
+*+Result:+"ab&cd"
+*+3.+Separators+{'~',+'='}
+*+Result:+"ab&cd-ef&gh"
+*
+*+@param+original+++the+original+string
+*+@param+characters+the+separators+until+the+substring+to+be+considered
+*+@return+the+substring+or+the+original+string+of+no+separator+exists
+*/
public+static+String+substringFirstOf(String+original,+List<Character>+characters)+{
++++return+characters.stream()
++++++++++++.map(original::indexOf)
++++++++++++.filter(min+->+min+>+0)
++++++++++++.reduce(Integer::min)
++++++++++++.map(position+->+original.substring(0,+position))
++++++++++++.orElse(original);
}|code-block|syntax|javascript|545891|entityMap^0|6|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

Here is code which returns a substring from a <code>String</code> until any of a given list of characters: 

<pre><code>/**
 * Return a substring of the given original string until the first appearance
 * of any of the given characters.
 * &lt;p&gt;
 * e.g. Original "ab&amp;cd-ef&amp;gh"
 * 1. Separators {'&amp;', '-'}
 * Result: "ab"
 * 2. Separators {'~', '-'}
 * Result: "ab&amp;cd"
 * 3. Separators {'~', '='}
 * Result: "ab&amp;cd-ef&amp;gh"
 *
 * @param original the original string
 * @param characters the separators until the substring to be considered
 * @return the substring or the original string of no separator exists
 */
public static String substringFirstOf(String original, List&lt;Character&gt; characters) {
 return characters.stream()
 .map(original::indexOf)
 .filter(min -&gt; min &gt; 0)
 .reduce(Integer::min)
 .map(position -&gt; original.substring(0, position))
 .orElse(original);
}
</code></pre>

blocks|key|762585|text|这可能会有所帮助：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|762586|public+static+String+getCorporateID(String+fileName)+{

++++String+corporateId+=+null;

++++try+{
++++++++corporateId+=+fileName.substring(0,+fileName.indexOf("_"));
++++++++//+System.out.println(new+Date()+%2B+":+"+%2B+"Corporate:
++++++++//+"%2BcorporateId);
++++++++return+corporateId;
++++}+catch+(Exception+e)+{
++++++++corporateId+=+null;
++++++++e.printStackTrace();
++++}

++++return+corporateId;
}|code-block|syntax|javascript|762587|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|$]]

This could help:

<pre><code>public static String getCorporateID(String fileName) {

 String corporateId = null;

 try {
 corporateId = fileName.substring(0, fileName.indexOf("_"));
 // System.out.println(new Date() + ": " + "Corporate:
 // "+corporateId);
 return corporateId;
 } catch (Exception e) {
 corporateId = null;
 e.printStackTrace();
 }

 return corporateId;
}
</code></pre>

blocks|key|762591|text|++private+String+getTextBefore(final+String+wholeString,+String+before){
+++final+int+indexOf+=+wholeString.indexOf(before);+
+++if(indexOf+!=+-1){
+++++++return+wholeString.substring(0,+indexOf);
+++}
+++return+wholeString;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|762592|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 String getTextBefore(final String wholeString, String before){
 final int indexOf = wholeString.indexOf(before); 
 if(indexOf != -1){
 return wholeString.substring(0, indexOf);
 }
 return wholeString;
}
</code></pre>

I have a string (which is basically a file name following a naming convention) <code>abc.def.ghi</code>

I would like to extract the substring before the first <code>.</code> (ie a dot)

In java doc api, I can't seem to find a method in String which does that. 
Am I missing something? How to do it?

In java how to get substring from a string till a character c?

我有一个字符串(基本上是一个遵循命名约定的文件名) abc.def.ghi我想提取第一个. (即一个点)之前的子串在java doc api中，我似乎无法在String中找到这样做的方法。我是不是遗漏了什么？该怎么做呢？

问在java中，如何从字符串中获取子字符串，直到字符c？
EN

回答 9

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问在java中，如何从字符串中获取子字符串，直到字符c？EN

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问在java中，如何从字符串中获取子字符串，直到字符c？
EN