blocks|key|1722572|text|Java+String对象有一个format方法(从1.5开始)，但没有join方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1722573|要获得一组尚未包含的有用的字符串实用程序方法，可以使用org.apache.commons.lang.StringUtils。|1722574|entityMap|0|LINK|mutability|MUTABLE|url|http://commons.apache.org/proper/commons-lang//apidocs/org/apache/commons/lang3/StringUtils.html^0|G|6|10|4|0|R|Z|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]|$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|U|8|@]|D|@$9|V|A|W|1|X]]|E|$]]|$1|H|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

The Java String object has a <code>format</code> method (as of 1.5), but no <code>join</code> method.

To get a bunch of useful String utility methods not already included you could use <a href="http://commons.apache.org/proper/commons-lang//apidocs/org/apache/commons/lang3/StringUtils.html" rel="noreferrer">org.apache.commons.lang.StringUtils</a>.

blocks|key|1507367|text|String.format。至于join，您需要自己编写：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1507368|+static+String+join(Collection<?>+s,+String+delimiter)+{
+++++StringBuilder+builder+=+new+StringBuilder();
+++++Iterator<?>+iter+=+s.iterator();
+++++while+(iter.hasNext())+{
+++++++++builder.append(iter.next());
+++++++++if+(!iter.hasNext())+{
+++++++++++break;++++++++++++++++++
+++++++++}
+++++++++builder.append(delimiter);
+++++}
+++++return+builder.toString();
+}|code-block|syntax|javascript|1507369|以上内容来自http://snippets.dzone.com/posts/show/91|1507370|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/j2se/1.5.0/docs/api/java/lang/String.html#format|1|http://snippets.dzone.com/posts/show/91^0|0|D|0|0|0|6|13|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]]]]

<a href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/String.html#format" rel="noreferrer">String.format</a>. As for join, you need to write your own:

<pre><code> static String join(Collection&lt;?&gt; s, String delimiter) {
 StringBuilder builder = new StringBuilder();
 Iterator&lt;?&gt; iter = s.iterator();
 while (iter.hasNext()) {
 builder.append(iter.next());
 if (!iter.hasNext()) {
 break; 
 }
 builder.append(delimiter);
 }
 return builder.toString();
 }
</code></pre>

The above comes from <a href="http://snippets.dzone.com/posts/show/91" rel="noreferrer">http://snippets.dzone.com/posts/show/91</a>

blocks|key|1722939|text|the+Joiner+class附带了Guava。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1722940|import+com.google.common.base.Joiner;

Joiner.on(separator).join(data);|code-block|syntax|javascript|1722941|entityMap|0|LINK|mutability|MUTABLE|url|http://google-collections.googlecode.com/svn/trunk/javadoc/com/google/common/base/Joiner.html|1|https://code.google.com/p/guava-libraries/^0|4|6|0|G|0|J|5|1|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]|$9|10|A|11|1|12]]|E|$]]|$1|F|3|G|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]|S|$5|N|O|P|E|$Q|T]]]]

<a href="https://code.google.com/p/guava-libraries/">Guava</a> comes with <a href="http://google-collections.googlecode.com/svn/trunk/javadoc/com/google/common/base/Joiner.html">the <code>Joiner</code> class</a>.

<pre><code>import com.google.common.base.Joiner;

Joiner.on(separator).join(data);
</code></pre>

blocks|key|1723150|text|从Java8开始，join()现在可以作为String类的两个类方法使用。在这两种情况下，第一个参数都是分隔符。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1723151|你可以使用pass+individual+CharSequences+as+additional+arguments|1723152|String+joined+=+String.join(",+",+"Antimony",+"Arsenic",+"Aluminum",+"Selenium");
//+"Antimony,+Arsenic,+Alumninum,+Selenium"|code-block|syntax|javascript|1723153|或者你也可以使用pass+an+Iterable|1723154|List<String>+strings+=+new+LinkedList<String>();
strings.add("EX");
strings.add("TER");
strings.add("MIN");
strings.add("ATE");

String+joined+=+String.join("-",+strings);
//+"EX-TER-MIN-ATE"|1723155|Java8还添加了一个新类StringJoiner，您可以像这样使用它：|1723156|StringJoiner+joiner+=+new+StringJoiner("&");
joiner.add("x=9");
joiner.add("y=5667.7");
joiner.add("z=-33.0");

String+joined+=+joiner.toString();
//+"x=9&y=5667.7&z=-33.0"|1723157|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/8/docs/api/java/lang/String.html#join-java.lang.CharSequence-java.lang.CharSequence...-|1|http://docs.oracle.com/javase/8/docs/api/java/lang/String.html#join-java.lang.CharSequence-java.lang.Iterable-|2|http://docs.oracle.com/javase/8/docs/api/java/util/StringJoiner.html^0|9|6|0|L|C|5|1H|0|0|0|G|8|8|G|1|0|0|D|C|D|C|2|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|19|8|@$9|1A|A|1B|B|C]]|D|@$9|1C|A|1D|1|1E]]|E|$]]|$1|H|3|I|5|J|7|1F|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1G|8|@$9|1H|A|1I|B|C]]|D|@$9|1J|A|1K|1|1L]]|E|$]]|$1|O|3|P|5|J|7|1M|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1N|8|@$9|1O|A|1P|B|C]]|D|@$9|1Q|A|1R|1|1S]]|E|$]]|$1|S|3|T|5|J|7|1T|8|@]|D|@]|E|$K|L]]|$1|U|3|-4|5|6|7|1U|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]|12|$5|X|Y|Z|E|$10|13]]|14|$5|X|Y|Z|E|$10|15]]]]

As of Java 8, <code>join()</code> is now available as two class methods on the String class. In both cases the first argument is the delimiter.

You can <a href="http://docs.oracle.com/javase/8/docs/api/java/lang/String.html#join-java.lang.CharSequence-java.lang.CharSequence...-">pass individual <code>CharSequence</code>s as additional arguments</a>:

<pre><code>String joined = String.join(", ", "Antimony", "Arsenic", "Aluminum", "Selenium");
// "Antimony, Arsenic, Alumninum, Selenium"
</code></pre>

Or you can <a href="http://docs.oracle.com/javase/8/docs/api/java/lang/String.html#join-java.lang.CharSequence-java.lang.Iterable-">pass an <code>Iterable&lt;? extends CharSequence&gt;</code></a>:

<pre><code>List&lt;String&gt; strings = new LinkedList&lt;String&gt;();
strings.add("EX");
strings.add("TER");
strings.add("MIN");
strings.add("ATE");

String joined = String.join("-", strings);
// "EX-TER-MIN-ATE"
</code></pre>

Java 8 also adds a new class, <a href="http://docs.oracle.com/javase/8/docs/api/java/util/StringJoiner.html"><code>StringJoiner</code></a>, which you can use like this:

<pre><code>StringJoiner joiner = new StringJoiner("&amp;");
joiner.add("x=9");
joiner.add("y=5667.7");
joiner.add("z=-33.0");

String joined = joiner.toString();
// "x=9&amp;y=5667.7&amp;z=-33.0"
</code></pre>

blocks|key|1723040|text|TextUtils.join在安卓系统上可用|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1723041|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/reference/android/text/TextUtils.html#join%2528java.lang.CharSequence,%2520java.lang.Iterable%2529^0|0|E|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]]]]

<a href="http://developer.android.com/reference/android/text/TextUtils.html#join%28java.lang.CharSequence,%20java.lang.Iterable%29" rel="noreferrer">TextUtils.join</a> is available on Android

blocks|key|1722919|text|您还可以将变量参数用于字符串，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1722920|++String+join+(String+delim,+String+...+data)+{
++++StringBuilder+sb+=+new+StringBuilder();
++++for+(int+i+=+0;+i+<+data.length;+i%2B%2B)+{
++++++sb.append(data[i]);
++++++if+(i+>=+data.length-1)+{break;}
++++++sb.append(delim);
++++}
++++return+sb.toString();
++}|code-block|syntax|javascript|1722921|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|$]]

You can also use variable arguments for strings as follows:

<pre><code> String join (String delim, String ... data) {
 StringBuilder sb = new StringBuilder();
 for (int i = 0; i &lt; data.length; i++) {
 sb.append(data[i]);
 if (i &gt;= data.length-1) {break;}
 sb.append(delim);
 }
 return sb.toString();
 }
</code></pre>

blocks|key|1507580|text|至于join，我相信这看起来可能不那么复杂：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1507581|public+String+join+(Collection<String>+c)+{
++++StringBuilder+sb=new+StringBuilder();
++++for(String+s:+c)
++++++++sb.append(s);
++++return+sb.toString();
}|code-block|syntax|javascript|1507582|我没有像我希望的那样使用Java5语法(信不信由你，我最近一直在使用1.0.x+)，所以我可能有点生疏了，但我确信这个概念是正确的。|1507583|编辑附加:字符串追加可能会很慢，但如果你正在处理图形用户界面代码或一些短时间运行的例程，那么无论你花的是.005秒还是.006，所以如果你有一个名为"joinMe“的集合，你想要附加到一个现有的字符串"target”上，那么内联这段代码并不可怕：|1507584|for(String+s+:+joinMe)
++++target+%2B=+s;|1507585|这是非常低效的(而且是一个坏习惯)，但是你不会察觉到任何东西，除非有成千上万的字符串，或者这是在一个巨大的循环中，或者你的代码是真正的性能关键。|1507586|更重要的是，它很容易记住，简短，快速，可读性很好。在设计选择中，性能并不总是自动的赢家。|1507587|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]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

As for join, I believe this might look a little less complicated:

<pre><code>public String join (Collection&lt;String&gt; c) {
 StringBuilder sb=new StringBuilder();
 for(String s: c)
 sb.append(s);
 return sb.toString();
}
</code></pre>

I don't get to use Java 5 syntax as much as I'd like (Believe it or not, I've been using 1.0.x lately) so I may be a bit rusty, but I'm sure the concept is correct.

edit addition: String appends can be slowish, but if you are working on GUI code or some short-running routine, it really doesn't matter if you take .005 seconds or .006, so if you had a collection called "joinMe" that you want to append to an existing string "target" it wouldn't be horrific to just inline this:

<pre><code>for(String s : joinMe)
 target += s;
</code></pre>

It's quite inefficient (and a bad habit), but not anything you will be able to perceive unless there are either thousands of strings or this is inside a huge loop or your code is really performance critical.

More importantly, it's easy to remember, short, quick and very readable. Performance isn't always the automatic winner in design choices.

blocks|key|1723224|text|这是一个非常简单的答案。使用%2B=，因为它的代码更少，让优化器为您将其转换为StringBuilder。使用这种方法，您不必在循环中执行任何"is+last“检查(性能改进)，也不必担心在结束时剥离任何分隔符。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1723225|++++++++Iterator<String>+iter+=+args.iterator();
++++++++output+%2B=+iter.hasNext()+?+iter.next()+:+"";
++++++++while+(iter.hasNext())+{
++++++++++++output+%2B=+","+%2B+iter.next();
++++++++}|code-block|syntax|javascript|1723226|entityMap^0|E|2|11|D|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Here is a pretty simple answer. Use <code>+=</code> since it is less code and let the optimizer convert it to a <code>StringBuilder</code> for you. Using this method, you don't have to do any "is last" checks in your loop (performance improvement) and you don't have to worry about stripping off any delimiters at the end.

<pre><code> Iterator&lt;String&gt; iter = args.iterator();
 output += iter.hasNext() ? iter.next() : "";
 while (iter.hasNext()) {
 output += "," + iter.next();
 }
</code></pre>

blocks|key|1508107|text|我不想导入整个Apache库来添加一个简单的连接函数，所以这里是我的技巧。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1508108|++++public+String+join(String+delim,+List<String>+destinations)+{
++++++++StringBuilder+sb+=+new+StringBuilder();
++++++++int+delimLength+=+delim.length();

++++++++for+(String+s:+destinations)+{
++++++++++++sb.append(s);
++++++++++++sb.append(delim);
++++++++}

++++++++//+we+have+appended+the+delimiter+to+the+end+
++++++++//+in+the+previous+for-loop.+Let's+now+remove+it.
++++++++if+(sb.length()+>=+delimLength)+{
++++++++++++return+sb.substring(0,+sb.length()+-+delimLength);
++++++++}+else+{
++++++++++++return+sb.toString();
++++++++}
++++}|code-block|syntax|javascript|1508109|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|$]]

I didn't want to import an entire Apache library to add a simple join function, so here's my hack.

<pre><code> public String join(String delim, List&lt;String&gt; destinations) {
 StringBuilder sb = new StringBuilder();
 int delimLength = delim.length();

 for (String s: destinations) {
 sb.append(s);
 sb.append(delim);
 }

 // we have appended the delimiter to the end 
 // in the previous for-loop. Let's now remove it.
 if (sb.length() &gt;= delimLength) {
 return sb.substring(0, sb.length() - delimLength);
 } else {
 return sb.toString();
 }
 }
</code></pre>

blocks|key|1722792|text|如果您希望将多个字符串连接(连接)为一个字符串，则应使用StringBuilder。它远比使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1722793|for(String+s+:+joinMe)
++++target+%2B=+s;|code-block|syntax|javascript|1722794|由于StringBuffer不使用同步，因此在性能上也略优于StringBuilder。|1722795|对于像这样的通用实用方法，它(最终)会在许多情况下被调用很多次，所以你应该使它高效，并且不要分配太多的临时对象。我们已经分析了许多不同的Java应用程序，并且几乎总是发现字符串连接和字符串/char[]分配占用了大量的时间/内存。|1722796|我们的可重用集合->字符串方法首先计算所需结果的大小，然后创建具有该初始大小的StringBuilder；这避免了对附加字符串时使用的内部char[]进行不必要的重复/复制。|1722797|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

If you wish to join (concatenate) several strings into one, you should use a StringBuilder. It is far better than using 

<pre><code>for(String s : joinMe)
 target += s;
</code></pre>

There is also a slight performance win over StringBuffer, since StringBuilder does not use synchronization.

For a general purpose utility method like this, it will (eventually) be called many times in many situations, so you should make it efficient and not allocate many transient objects. We've profiled many, many different Java apps and almost always find that string concatenation and string/char[] allocations take up a significant amount of time/memory.

Our reusable collection -> string method first calculates the size of the required result and then creates a StringBuilder with that initial size; this avoids unecessary doubling/copying of the internal char[] used when appending strings.

blocks|key|1507936|text|我写了自己的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1507937|public+static+String+join(Collection<String>+col,+String+delim)+{
++++StringBuilder+sb+=+new+StringBuilder();
++++Iterator<String>+iter+=+col.iterator();
++++if+(iter.hasNext())
++++++++sb.append(iter.next().toString());
++++while+(iter.hasNext())+{
++++++++sb.append(delim);
++++++++sb.append(iter.next().toString());
++++}
++++return+sb.toString();
}|code-block|syntax|javascript|1507938|但是JSP不支持Collection，所以对于标记函数，我写了：|offset|length|style|CODE|1507939|public+static+String+join(List<?>+list,+String+delim)+{
++++int+len+=+list.size();
++++if+(len+==+0)
++++++++return+"";
++++StringBuilder+sb+=+new+StringBuilder(list.get(0).toString());
++++for+(int+i+=+1;+i+<+len;+i%2B%2B)+{
++++++++sb.append(delim);
++++++++sb.append(list.get(i).toString());
++++}
++++return+sb.toString();
}|1507940|并放入.tld文件：|1507941|<?xml+version="1.0"+encoding="UTF-8"?>
<taglib+version="2.1"+xmlns="http://java.sun.com/xml/ns/javaee"
++++<function>
++++++++<name>join</name>
++++++++<function-class>com.core.util.ReportUtil</function-class>
++++++++<function-signature>java.lang.String+join(java.util.List,+java.lang.String)</function-signature>
++++</function>
</taglib>|1507942|并在JSP文件中将其用作：|1507943|<%25@taglib+prefix="funnyFmt"+uri="tag:com.core.util,2013:funnyFmt"%25>
${funnyFmt:join(books,+",+")}|1507944|entityMap^0|0|0|8|A|0|0|3|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@$I|11|J|12|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|14|8|@$I|15|J|16|K|L]]|9|@]|A|$]]|$1|Q|3|R|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|18|8|@]|9|@]|A|$]]|$1|U|3|V|5|D|7|19|8|@]|9|@]|A|$E|F]]|$1|W|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|X|$]]

I wrote own:

<pre><code>public static String join(Collection&lt;String&gt; col, String delim) {
 StringBuilder sb = new StringBuilder();
 Iterator&lt;String&gt; iter = col.iterator();
 if (iter.hasNext())
 sb.append(iter.next().toString());
 while (iter.hasNext()) {
 sb.append(delim);
 sb.append(iter.next().toString());
 }
 return sb.toString();
}
</code></pre>

but <code>Collection</code> isn't supported by JSP, so for tag function I wrote:

<pre><code>public static String join(List&lt;?&gt; list, String delim) {
 int len = list.size();
 if (len == 0)
 return "";
 StringBuilder sb = new StringBuilder(list.get(0).toString());
 for (int i = 1; i &lt; len; i++) {
 sb.append(delim);
 sb.append(list.get(i).toString());
 }
 return sb.toString();
}
</code></pre>

and put to <code>.tld</code> file:

<pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;taglib version="2.1" xmlns="http://java.sun.com/xml/ns/javaee"
 &lt;function&gt;
 &lt;name&gt;join&lt;/name&gt;
 &lt;function-class&gt;com.core.util.ReportUtil&lt;/function-class&gt;
 &lt;function-signature&gt;java.lang.String join(java.util.List, java.lang.String)&lt;/function-signature&gt;
 &lt;/function&gt;
&lt;/taglib&gt;
</code></pre>

and use it in JSP files as:

<pre><code>&lt;%@taglib prefix="funnyFmt" uri="tag:com.core.util,2013:funnyFmt"%&gt;
${funnyFmt:join(books, ", ")}
</code></pre>

blocks|key|1722842|text|StringUtils是Apache+Commons+Lang库中一个非常有用的类。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1722843|entityMap|0|LINK|mutability|MUTABLE|url|http://commons.apache.org/lang/api/org/apache/commons/lang/StringUtils.html^0|0|B|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]]]]

<a href="http://commons.apache.org/lang/api/org/apache/commons/lang/StringUtils.html" rel="nofollow noreferrer">StringUtils</a> is a pretty useful class in the Apache Commons Lang library.

blocks|key|1723243|text|有一个类似于C#的String.Format()的MessageFormat.format()。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1723244|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/7/docs/api/java/text/MessageFormat.html#format(java.lang.String,%2520java.lang.Object...)^0|9|F|P|M|P|M|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@$9|S|A|T|1|U]]|E|$]]|$1|F|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

There is <a href="http://docs.oracle.com/javase/7/docs/api/java/text/MessageFormat.html#format(java.lang.String,%20java.lang.Object...)" rel="nofollow"><code>MessageFormat.format()</code></a> which works like C#'s <code>String.Format()</code>.

blocks|key|1723273|text|我在这里看到了很多过于复杂的String.Join实现。如果你没有Java+1.8，并且你不想导入一个新的库，下面的实现应该就足够了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1723274|public+String+join(Collection<String>+col,+String+delim)+{
++++StringBuilder+sb+=+new+StringBuilder();
++++for+(+String+s+:+col+)+{
++++++++if+(+sb.length()+!=+0+)+sb.append(delim);
++++++++sb.append(s);
++++}
++++return+sb.toString();
}|code-block|syntax|javascript|1723275|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|$]]

I see a lot of overly complex implementations of String.Join here. If you don't have Java 1.8, and you don't want to import a new library the below implementation should suffice.

<pre><code>public String join(Collection&lt;String&gt; col, String delim) {
 StringBuilder sb = new StringBuilder();
 for ( String s : col ) {
 if ( sb.length() != 0 ) sb.append(delim);
 sb.append(s);
 }
 return sb.toString();
}
</code></pre>

blocks|key|1508020|text|ArrayList<Double>+j=new+ArrayList<>;+
j.add(1);
j.add(.92);
j.add(3);+
String+ntop=j.toString();+//ntop=+"[1,+0.92,+3]"+|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1508021|所以基本上，字符串ntop使用逗号分隔符和括号存储整个集合的值。|unstyled|1508022|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>ArrayList&lt;Double&gt; j=new ArrayList&lt;&gt;; 
j.add(1);
j.add(.92);
j.add(3); 
String ntop=j.toString(); //ntop= "[1, 0.92, 3]" 
</code></pre>

So basically, the String ntop stores the value of the entire collection with comma separators and brackets.

blocks|key|1507748|text|我只需要使用字符串连接运算符"%2B“来连接两个字符串。s1+%2B=+s2;|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1507749|entityMap^0|Q|9|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

I would just use the string concatenation operator "+" to join two strings. <code>s1 += s2;</code>

I know this is a bit of a newbie question, but are there equivalents to C#'s string operations in Java?

Specifically, I'm talking about <code>String.Format</code> and <code>String.Join</code>.

Java equivalents of C# String.Format() and String.Join()

Java

我知道这是一个有点新手的问题，但是在Java中有与C#的字符串操作等效的东西吗？具体地说，我指的是String.Format和String.Join。

问C# String.Format()和String.Join()的Java等效项
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回答 16

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