Can I multiply strings in Java to repeat sequences?

user_88470 0
Viewed 206028

I have something like the following:

int i = 3;
String someNum = "123";

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

So I could just go:

someNum = sumNum + ("0" * 3);

or something similar?

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

"123000".

java string
19 Answers

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:

    <dependency>
        <groupId>commons-lang</groupId>
        <artifactId>commons-lang</artifactId>
        <version>2.4</version>
    </dependency>

And then use StringUtils.repeat as follows:

import org.apache.commons.lang.StringUtils
...
someNum = sumNum + StringUtils.repeat("0", 3);
user_394890

Two ways comes to mind:

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

Way 2 can be shortened to:

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

More about String#format() is available in its API doc and the one of java.util.Formatter.

user_1578820

No. Java does not have this feature. You'd have to create your String using a StringBuilder, and a loop of some sort.

user_316100

with Dollar:

String s = "123" + $("0").repeat(3); // 123000
user_892660

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

However StringUtils in commons-lang provides this feature. The method is called repeat(). Your only other option is to build it manually using a loop.

user_2630040

With Guava:

Joiner.on("").join(Collections.nCopies(i, someNum));
finnw_120480

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

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

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

    return b.toString();
}

Disclaimer: I typed it here. Might have mistakes.

user_2511540

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

You'd have to do this:

for (;i > 0; i--) {
    somenum = somenum + "0";
}
user_2460140
Related