如何在一行中替换多个字符串？

Question

I want to insert "OB" before every vowel. I have tried the code below:

String out=txt.toUpperCase();

out=out.replaceAll("A","OBA");
out=out.replaceAll("E","OBE");
out=out.replaceAll("I","OBI");
out=out.replaceAll("O","OBO");
out=out.replaceAll("U","OBU");
out=out.replaceAll("Y","OBY");

When I use that code above, it replaces A with OBA , but then when it comes to replacing O to OBO it replaces the O from the original text and also the O in OBA . For example, for "I WON'T" I want the output "OBI WOBON'T" , but instead it gives "OBOBI WOBON'T" as the O from OBI from the first line has been treated as a vowel.

I need a solution which doesn't replace the new O from the encryption.

Answer 1

Since replaceAll takes regex, you can use references to captured elements in your replacement string:

out=out.replaceAll("[AEIOUY]", "OB$0");

• [AEIOUY] captures a single character from the AEIOUY list
• $0 in the replacement string stands for the character that has been captured.

Here is a demo .

Answer 2

您可以使用$1来引用匹配的组，因此替换为AB$1 ：

out.replaceAll("([AEIOUY])", "OB$1")

Answer 3

move "O","OBO" to the start will prevent duplication

String out=txt.toUpperCase();

out=out.replaceAll("O","OBO");
out=out.replaceAll("A","OBA");
out=out.replaceAll("E","OBE");
out=out.replaceAll("I","OBI");
out=out.replaceAll("U","OBU");
out=out.replaceAll("Y","OBY");

Answer 4

If you don't want to use regexes:

HashMap<Character, String> replace = new HashMap<Character, String>() {{
            put('A',"OBA");
            put('E',"OBE");
            put('I',"OBI");
            put('O',"OBO");
            put('U',"OBU");
            put('Y',"OBY");
}};

final StringBuilder res = new StringBuilder();
String test = "I WON'T";

test
 .chars()
 .mapToObj(c -> (char) c)
 .forEach(c -> res.append(replace.getOrDefault(c, Character.toString(c))));
System.out.println(res);

Answer 5

Something like this can also be done, replace OB with '-@' (any 2 characters that we can be sure of would not appear in the string) and in the end replace them with OB:

public static void main(String[] args) { String text = "I WON'T";

text = text.replaceAll("A", "-@A");
text = text.replaceAll("E", "-@E");
text = text.replaceAll("I", "-@I");
text = text.replaceAll("O", "-@O");
text = text.replaceAll("U", "-@U");
text = text.replaceAll("Y", "-@Y");
System.out.println(text);       
text = text.replaceAll("-@", "OB");     
System.out.println(text);
}

output

-@I W-@ON'T OBI WOBON'T