字符串操作每第4个字符插入一个字符 [英] String Manipulation insert a character every 4th character

问题描述

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

In Android if I have an edit text and the user entered 123456789012, how could I get the program to insert a dash every 4th character. ie: 1234-5678-9012?

我想您需要按照以下方式讲: a=Characters 1~4, b=Characters 5~8, c=Characters 9-12，结果 = a +-" + b +-" + c .但是我不确定在Android中会如何.

I guess you need to say something along the lines of:- a=Characters 1~4, b=Characters 5~8, c=Characters 9-12, Result = a + "-" + b + "-" + c. But I am unsure of how that would look in Android.

非常感谢您的帮助.

推荐答案

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

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