blocks|key|1114550|text|不能，但在Scala中可以！(然后编译它并使用任何Java实现运行它！)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1114551|现在，如果您想在java中使用简单的方法，请使用Apache+commons-lang包。假设你使用的是maven，将这个依赖添加到你的pom.xml中：|1114552|++++<dependency>
++++++++<groupId>commons-lang</groupId>
++++++++<artifactId>commons-lang</artifactId>
++++++++<version>2.4</version>
++++</dependency>|code-block|syntax|javascript|1114553|然后使用StringUtils.repeat，如下所示：|1114554|import+org.apache.commons.lang.StringUtils
...
someNum+=+sumNum+%2B+StringUtils.repeat("0",+3);|1114555|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|$]]

No, but you can in Scala! (And then compile that and run it using any Java implementation!!!!)

Now, if you want to do it the easy way in java, use the Apache commons-lang package. Assuming you're using maven, add this dependency to your pom.xml:

<pre><code> &lt;dependency&gt;
 &lt;groupId&gt;commons-lang&lt;/groupId&gt;
 &lt;artifactId&gt;commons-lang&lt;/artifactId&gt;
 &lt;version&gt;2.4&lt;/version&gt;
 &lt;/dependency&gt;
</code></pre>

And then use StringUtils.repeat as follows:

<pre><code>import org.apache.commons.lang.StringUtils
...
someNum = sumNum + StringUtils.repeat("0", 3);
</code></pre>

blocks|key|1330148|text|使用Strings#repeat()，Google+Guava提供了另一种方法来实现这一点|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1330149|String+repeated+=+Strings.repeat("pete+and+re",+42);|code-block|syntax|javascript|1330150|entityMap|0|LINK|mutability|MUTABLE|url|https://google.github.io/guava/releases/23.0/api/docs/com/google/common/base/Strings.html#repeat-java.lang.String-int-|1|http://code.google.com/p/guava-libraries/^0|2|G|2|G|0|J|C|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="http://code.google.com/p/guava-libraries/" rel="noreferrer">Google Guava</a> provides another way to do this with <a href="https://google.github.io/guava/releases/23.0/api/docs/com/google/common/base/Strings.html#repeat-java.lang.String-int-" rel="noreferrer"><code>Strings#repeat()</code></a>:

<pre><code>String repeated = Strings.repeat("pete and re", 42);
</code></pre>

blocks|key|1114848|text|我想到了两种方式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1114849|int+i+=+3;
String+someNum+=+"123";

//+Way+1:
char[]+zeroes1+=+new+char[i];
Arrays.fill(zeroes1,+'0');
String+newNum1+=+someNum+%2B+new+String(zeroes1);
System.out.println(newNum1);+//+123000

//+Way+2:
String+zeroes2+=+String.format("%250"+%2B+i+%2B+"d",+0);
String+newNum2+=+someNum+%2B+zeroes2;
System.out.println(newNum2);+//+123000|code-block|syntax|javascript|1114850|方法2可以缩写为：|1114851|someNum+%2B=+String.format("%250"+%2B+i+%2B+"d",+0);
System.out.println(someNum);+//+123000|1114852|有关String#format()的更多信息，请访问its+API+doc和java.util.Formatter。|offset|length|style|CODE|1114853|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/javase/6/docs/api/java/lang/String.html#format%2528java.lang.String,%2520java.lang.Object...%2529|1|http://java.sun.com/javase/6/docs/api/java/util/Formatter.html^0|0|0|0|0|2|F|12|J|Q|B|0|12|J|1|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|12|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|14|8|@$M|15|N|16|O|P]|$M|17|N|18|O|P]]|9|@$M|19|N|1A|1|1B]|$M|1C|N|1D|1|1E]]|A|$]]|$1|Q|3|-4|5|6|7|1F|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]|Y|$5|T|U|V|A|$W|Z]]]]

Two ways comes to mind:

<pre><code>int i = 3;
String someNum = "123";

// Way 1:
char[] zeroes1 = new char[i];
Arrays.fill(zeroes1, '0');
String newNum1 = someNum + new String(zeroes1);
System.out.println(newNum1); // 123000

// Way 2:
String zeroes2 = String.format("%0" + i + "d", 0);
String newNum2 = someNum + zeroes2;
System.out.println(newNum2); // 123000
</code></pre>

Way 2 can be shortened to:

<pre><code>someNum += String.format("%0" + i + "d", 0);
System.out.println(someNum); // 123000
</code></pre>

More about <code>String#format()</code> is available in <a href="http://java.sun.com/javase/6/docs/api/java/lang/String.html#format%28java.lang.String,%20java.lang.Object...%29" rel="noreferrer">its API doc</a> and the one of <a href="http://java.sun.com/javase/6/docs/api/java/util/Formatter.html" rel="noreferrer"><code>java.util.Formatter</code></a>.

blocks|key|1115086|text|如果像OP这样重复单个字符，并且最大重复次数不是太高，那么可以使用简单的子字符串操作，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1115087|int+i+=+3;
String+someNum+=+"123";
someNum+%2B=+"00000000000000000000".substring(0,+i);|code-block|syntax|javascript|1115088|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|$]]

If you're repeating single characters like the OP, and the maximum number of repeats is not too high, then you could use a simple substring operation like this:

<pre><code>int i = 3;
String someNum = "123";
someNum += "00000000000000000000".substring(0, i);
</code></pre>

blocks|key|1329774|text|不是的。Java没有这个特性。您必须使用StringBuilder和某种类型的循环来创建字符串。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1329775|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/j2se/1.5.0/docs/api/java/lang/StringBuilder.html^0|K|D|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]]]]

No. Java does not have this feature. You'd have to create your String using a <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/StringBuilder.html" rel="noreferrer">StringBuilder</a>, and a loop of some sort.

blocks|key|1115134|text|做这件事的简单方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1115135|private+String+repeatString(String+s,int+count){
++++StringBuilder+r+=+new+StringBuilder();
++++for+(int+i+=+0;+i+<+count;+i%2B%2B)+{
++++++++r.append(s);
++++}
++++return+r.toString();
}|code-block|syntax|javascript|1115136|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|$]]

Simple way of doing this.

<pre><code>private String repeatString(String s,int count){
 StringBuilder r = new StringBuilder();
 for (int i = 0; i &lt; count; i++) {
 r.append(s);
 }
 return r.toString();
}
</code></pre>

blocks|key|1330443|text|Java+8提供了一种方法(尽管有点笨拙)。作为一种方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1330444|public+static+String+repeat(String+s,+int+n)+{
++++return+Stream.generate(()+->+s).limit(n).collect(Collectors.joining(""));
}|code-block|syntax|javascript|1330445|或者效率较低，但看起来更漂亮：|1330446|public+static+String+repeat(String+s,+int+n)+{
++++return+Stream.generate(()+->+s).limit(n).reduce((a,+b)+->+a+%2B+b);
}|1330447|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|$]]

Java 8 provides a way (albeit a little clunky). As a method:

<pre><code>public static String repeat(String s, int n) {
 return Stream.generate(() -&gt; s).limit(n).collect(Collectors.joining(""));
}
</code></pre>

or less efficient, but nicer looking IMHO:

<pre><code>public static String repeat(String s, int n) {
 return Stream.generate(() -&gt; s).limit(n).reduce((a, b) -&gt; a + b);
}
</code></pre>

blocks|key|1115360|text|我创建了一个方法，它可以做你想做的事情，请随意尝试：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1115361|public+String+repeat(String+s,+int+count)+{
++++return+count+>+0+?+s+%2B+repeat(s,+--count)+:+"";
}|code-block|syntax|javascript|1115362|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 created a method that do the same thing you want, feel free to try this:

<pre><code>public String repeat(String s, int count) {
 return count &gt; 0 ? s + repeat(s, --count) : "";
}
</code></pre>

blocks|key|1114927|text|使用Dollar|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1114928|String+s+=+"123"+%2B+$("0").repeat(3);+//+123000|code-block|syntax|javascript|1114929|entityMap|0|LINK|mutability|MUTABLE|url|http://bitbucket.org/dfa/dollar^0|2|6|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]]]]

with <a href="http://bitbucket.org/dfa/dollar" rel="noreferrer">Dollar</a>:

<pre><code>String s = "123" + $("0").repeat(3); // 123000
</code></pre>

blocks|key|1329923|text|我不相信Java本身就提供了这个特性，尽管它会很好。我偶尔会编写Perl代码，对于重复字符串，Perl中的x操作符非常方便！|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1329924|然而，commons-lang中的StringUtils+provides此功能。该方法称为repeat()。您唯一的其他选择是使用循环手动构建它。|1329925|entityMap|0|LINK|mutability|MUTABLE|url|http://commons.apache.org/lang/api-release/org/apache/commons/lang/StringUtils.html#repeat(java.lang.String,%2520int)^0|1H|1|0|3|C|H|B|1A|8|T|8|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|H|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

I don't believe Java natively provides this feature, although it would be nice. I write Perl code occasionally and the <code>x</code> operator in Perl comes in really handy for repeating strings!

However <code>StringUtils</code> in <code>commons-lang</code> <a href="http://commons.apache.org/lang/api-release/org/apache/commons/lang/StringUtils.html#repeat(java.lang.String,%20int)" rel="nofollow noreferrer">provides</a> this feature. The method is called <code>repeat()</code>. Your only other option is to build it manually using a loop.

blocks|key|1114904|text|使用Guava|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1114905|Joiner.on("").join(Collections.nCopies(i,+someNum));|code-block|syntax|javascript|1114906|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/p/guava-libraries/^0|2|5|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]]]]

With <a href="http://code.google.com/p/guava-libraries/" rel="nofollow noreferrer">Guava</a>:

<pre><code>Joiner.on("").join(Collections.nCopies(i, someNum));
</code></pre>

blocks|key|1330034|text|不，你不能。但是你可以使用这个函数来重复一个字符。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1330035|public+String+repeat(char+c,+int+times){
++++StringBuffer+b+=+new+StringBuffer();

++++for(int+i=0;i+&lt;+times;i%2B%2B){
++++++++b.append(c);
++++}

++++return+b.toString();
}|code-block|syntax|javascript|1330036|免责声明:我在这里输入了它。可能会有错误。|1330037|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

No, you can't. However you can use this function to repeat a character.

<pre><code>public String repeat(char c, int times){
 StringBuffer b = new StringBuffer();

 for(int i=0;i &amp;lt; times;i++){
 b.append(c);
 }

 return b.toString();
}
</code></pre>

Disclaimer: I typed it here. Might have mistakes.

blocks|key|1330362|text|Dave+Hartnoll的答案的概括(我主要采用荒谬的概念，也许不要在任何需要速度的地方使用它)。这允许用户使用给定模式后的i个字符来填充字符串。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1330363|int+i+=+3;
String+someNum+=+"123";
String+pattern+=+"789";
someNum+%2B=+"00000000000000000000".replaceAll("0",pattern).substring(0,+i);|code-block|syntax|javascript|1330364|如果你不需要模式，而只需要单个字符，你可以使用它(它的速度要快一点)：|1330365|int+i+=+3;
String+someNum+=+"123";
char+c+=+"7";
someNum+%2B=+"00000000000000000000".replaceAll("0",c).substring(0,+i);|1330366|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|$]]

A generalisation of Dave Hartnoll's answer (I am mainly taking the concept ad absurdum, maybe don't use that in anything where you need speed).
This allows one to fill the String up with i characters following a given pattern.

<pre><code>int i = 3;
String someNum = "123";
String pattern = "789";
someNum += "00000000000000000000".replaceAll("0",pattern).substring(0, i);
</code></pre>

If you don't need a pattern but just any single character you can use that (it's a tad faster):

<pre><code>int i = 3;
String someNum = "123";
char c = "7";
someNum += "00000000000000000000".replaceAll("0",c).substring(0, i);
</code></pre>

blocks|key|1115326|text|与前面所说的类似：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1115327|public+String+multStuff(String+first,+String+toAdd,+int+amount)+{+
++++String+append+=+"";
++++for+(int+i+=+1;+i+<=+amount;+i%2B%2B)+{
++++++++append+%2B=+toAdd;+++++++++++++++
++++}
++++return+first+%2B+append;
}|code-block|syntax|javascript|1115328|输入multStuff("123",+"0",+3);|offset|length|style|CODE|1115329|输出"123000"|1115330|entityMap^0|0|0|2|P|0|2|8|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@$I|W|J|X|K|L]]|9|@]|A|$]]|$1|O|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|P|$]]

Similar to what has already been said:

<pre><code>public String multStuff(String first, String toAdd, int amount) { 
 String append = "";
 for (int i = 1; i &lt;= amount; i++) {
 append += toAdd; 
 }
 return first + append;
}
</code></pre>

Input <code>multStuff("123", "0", 3);</code>

Output <code>"123000"</code>

blocks|key|1330562|text|我们可以在python中使用*创建多个字符串，但在java中不能，你可以在你的例子中使用for循环：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1330563|String+sample="123";
for(int+i=0;i<3;i%2B%2B)
{
sample=%2B"0";
}|code-block|syntax|javascript|1330564|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|$]]

we can create multiply strings using * in python but not in java you can use for loop in your case:

<pre><code>String sample="123";
for(int i=0;i&lt;3;i++)
{
sample=+"0";
}
</code></pre>

blocks|key|1114791|text|在Java中没有捷径可以做到这一点，就像您在Python中给出的示例一样。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1114792|你必须这样做：|1114793|for+(;i+>+0;+i--)+{
++++somenum+=+somenum+%2B+"0";
}|code-block|syntax|javascript|1114794|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

There's no shortcut for doing this in Java like the example you gave in Python.

You'd have to do this:

<pre><code>for (;i &gt; 0; i--) {
 somenum = somenum + "0";
}
</code></pre>

blocks|key|1330082|text|最简单的方法是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1330083|String+someNum+=+"123000";
System.out.println(someNum);|code-block|syntax|javascript|1330084|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 simplest way is:

<pre><code>String someNum = "123000";
System.out.println(someNum);
</code></pre>

I have something like the following:

<pre><code>int i = 3;
String someNum = "123";
</code></pre>

I'd like to append <code>i</code> "0"s to the <code>someNum</code> string. Does it have some way I can multiply a string to repeat it like Python does?

So I could just go:

<pre><code>someNum = sumNum + ("0" * 3);
</code></pre>

or something similar?

Where, in this case, my final result would be:

"123000".

Can I multiply strings in Java to repeat sequences?

Python

Java

Perl

我有一些类似以下的东西：int i = 3;String someNum = "123";我想将i“0”附加到someNum字符串。它有没有什么方法可以像Python那样乘以一个字符串来重复它呢？所以我可以直接说：someNum = sumNum + ("0" * 3);或者类似的东西？在这种情况下，我的最终结果是："123000“。

问我可以在Java中将字符串相乘以重复序列吗？
EN

回答 17

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问我可以在Java中将字符串相乘以重复序列吗？EN

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问我可以在Java中将字符串相乘以重复序列吗？
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