重复字符串的简单方法

我正在寻找一个简单的公共方法或操作符，允许我重复一些字符串n次。我知道我可以使用for循环来写这个，但我希望在必要时避免for循环，并且应该在某个地方存在一个简单的直接方法。

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

repeated.equals("abcabcabc");

相关:

重复字符串javascript 通过重复给定次数的另一个字符串创建NSString

编辑

当它们不是完全必要的时候，我尽量避免使用for循环，因为:

They add to the number of lines of code even if they are tucked away in another function. Someone reading my code has to figure out what I am doing in that for loop. Even if it is commented and has meaningful variables names, they still have to make sure it is not doing anything "clever". Programmers love to put clever things in for loops, even if I write it to "only do what it is intended to do", that does not preclude someone coming along and adding some additional clever "fix". They are very often easy to get wrong. For loops involving indexes tend to generate off by one bugs. For loops often reuse the same variables, increasing the chance of really hard to find scoping bugs. For loops increase the number of places a bug hunter has to look.

当前回答

如果你只知道输出字符串的长度(它可能不能被输入字符串的长度整除)，那么使用这个方法:

static String repeat(String s, int length) {
    return s.length() >= length ? s.substring(0, length) : repeat(s + s, length);
}

使用演示:

for (int i = 0; i < 50; i++)
    System.out.println(repeat("_/‾\\", i));

不要使用空s，长度为> 0，因为在这种情况下不可能得到想要的结果。

2020-05-18 19:16:54

其他回答

public static String rep(int a,String k)

       {
           if(a<=0)
                return "";
           else 
           {a--;
               return k+rep(a,k);
       }

你可以使用这种递归方法实现你想要的目标。

2019-08-09 16:03:36

试试这个吧:

public static char[] myABCs = {'a', 'b', 'c'};
public static int numInput;
static Scanner in = new Scanner(System.in);

public static void main(String[] args) {
    System.out.print("Enter Number of Times to repeat: ");
    numInput = in.nextInt();
    repeatArray(numInput);
}

public static int repeatArray(int y) {
    for (int a = 0; a < y; a++) {
        for (int b = 0; b < myABCs.length; b++) {
            System.out.print(myABCs[b]);                
        }
        System.out.print(" ");
    }
    return y;
}

2013-11-13 14:25:22

我想要一个函数来为JDBC创建一个以逗号分隔的问号列表，然后找到了这篇文章。所以，我决定采用两个变体，看看哪个表现更好。在100万次迭代之后，普通的StringBuilder花了2秒(fun1)，而神秘的最优版本(fun2)花了30秒。又变得神秘有什么意义?

private static String fun1(int size) {
    StringBuilder sb = new StringBuilder(size * 2);
    for (int i = 0; i < size; i++) {
        sb.append(",?");
    }
    return sb.substring(1);
}

private static String fun2(int size) {
    return new String(new char[size]).replaceAll("\0", ",?").substring(1);
}

2012-12-06 14:42:04

这比你的问题包含的字符少

public static String repeat(String s, int n) {
    if(s == null) {
        return null;
    }
    final StringBuilder sb = new StringBuilder(s.length() * n);
    for(int i = 0; i < n; i++) {
        sb.append(s);
    }
    return sb.toString();
}

2009-08-05 19:23:28

如果你像我一样想使用谷歌Guava而不是Apache Commons。你可以在Guava Strings类中使用repeat方法。

Strings.repeat("-", 60);

2012-05-20 23:33:29

重复字符串的简单方法

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