字符串操作每 4 个字符插入一个字符

发布于 2024-10-02 13:56:54 字数 256 浏览 3 评论 0原文

在 Android 中，如果我有一个编辑文本并且用户输入 123456789012，我怎样才能让程序每 4 个字符插入一个破折号。 即：1234-5678-9012？

我想你需要说一些类似的话：- a=字符1~4，b=字符5~8，c=字符9-12，结果= a + "-" + b + "-" + c 。但我不确定这在 Android 中会是什么样子。

非常感谢您的帮助。

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奢华的一滴泪 2024-10-09 13:56:54

String s = "123456789012";
String s1 = s.substring(0, 4);
String s2 = s.substring(4, 8);
String s3 = s.substring(8, 12);

String dashedString = s1 + "-" + s2 + "-" + s3;
//String.format is extremely slow. Just concatenate them, as above.

substring() 参考

String s = "123456789012";
String s1 = s.substring(0, 4);
String s2 = s.substring(4, 8);
String s3 = s.substring(8, 12);

String dashedString = s1 + "-" + s2 + "-" + s3;
//String.format is extremely slow. Just concatenate them, as above.

substring() Reference

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丿*梦醉红颜 2024-10-09 13:56:54

或者使用 StringBuilder 的另一种替代方法，而不是将字符串拆分为多个部分，然后将它们连接起来：

String original = "123456789012";
int interval = 4;
char separator = '-';

StringBuilder sb = new StringBuilder(original);

for(int i = 0; i < original.length() / interval; i++) {
    sb.insert(((i + 1) * interval) + i, separator);
}

String withDashes = sb.toString();

Or another alternative way using a StringBuilder rather than to split the string in multiple parts and then join them :

String original = "123456789012";
int interval = 4;
char separator = '-';

StringBuilder sb = new StringBuilder(original);

for(int i = 0; i < original.length() / interval; i++) {
    sb.insert(((i + 1) * interval) + i, separator);
}

String withDashes = sb.toString();

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三生一梦 2024-10-09 13:56:54

替代方法：

String original = "123456789012";
int dashInterval = 4;
String withDashes = original.substring(0, dashInterval);
for (int i = dashInterval; i < original.length(); i += dashInterval) {
    withDashes += "-" + original.substring(i, i + dashInterval);
}

return withDashes;

如果您需要传递长度不是 dashInterval 倍数的字符串，则必须编写一个额外的位来处理它，以防止索引越界废话。

Alternative way:

String original = "123456789012";
int dashInterval = 4;
String withDashes = original.substring(0, dashInterval);
for (int i = dashInterval; i < original.length(); i += dashInterval) {
    withDashes += "-" + original.substring(i, i + dashInterval);
}

return withDashes;

If you needed to pass strings with lengths that were not multiples of the dashInterval you'd have to write an extra bit to handle that to prevent index out of bounds nonsense.

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