Simple way to repeat a string

String::repeat

". ".repeat(7)  // Seven period-with-space pairs: . . . . . . . 

New in Java 11 is the method String::repeat that does exactly what you asked for:

String str = "abc";
String repeated = str.repeat(3);
repeated.equals("abcabcabc");

Its Javadoc says:

/**
 * Returns a string whose value is the concatenation of this
 * string repeated {@code count} times.
 * <p>
 * If this string is empty or count is zero then the empty
 * string is returned.
 *
 * @param count number of times to repeat
 *
 * @return A string composed of this string repeated
 * {@code count} times or the empty string if this
 * string is empty or count is zero
 *
 * @throws IllegalArgumentException if the {@code count} is
 * negative.
 *
 * @since 11
 */ 

If you are using Java <= 7, this is as "concise" as it gets:

// create a string made up of n copies of string s
String.format("%0" + n + "d", 0).replace("0", s);

In Java 8 and above there is a more readable way:

// create a string made up of n copies of string s
String.join("", Collections.nCopies(n, s));

Finally, for Java 11 and above, there is a new repeat​(int count) method specifically for this purpose(link)

"abc".repeat(12);

Alternatively, if your project uses java libraries there are more options.

For Apache Commons:

StringUtils.repeat("abc", 12);

For Google Guava:

Strings.repeat("abc", 12);

Commons Lang StringUtils.repeat()

Usage:

String str = "abc";
String repeated = StringUtils.repeat(str, 3);

repeated.equals("abcabcabc");

Here is the shortest version (Java 1.5+ required):

repeated = new String(new char[n]).replace("\0", s);

Where n is the number of times you want to repeat the string and s is the string to repeat.

No imports or libraries needed.