Why Isn't My Java String Replace Method Working?-javaTutorial-php.cn

Why Isn't My Java String Replace Method Working?

Susan Sarandon

Release： 2024-11-26 04:16:12

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Why Isn't My Java String Replace Method Working?

Troubleshooting Java String Replace Issue

When working with Java strings, it's important to remember that strings are immutable. This means that any changes made to a string create a new string object rather than modifying the existing one.

Consider the following code:

String delimiter = "\*\*";
String html = "<html><head></head><body>**USERNAME** AND **PASSWORD**</body></html>";
Map<String, String> mp = new HashMap<String, String>();
mp.put("USERNAME", "User A");
mp.put("PASSWORD", "B");
for (Entry<String, String> entry : mp.entrySet()) {
  html.replace(delimiter + entry.getKey()+ delimiter, entry.getValue());
}

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You may expect this code to replace the "USERNAME" and "PASSWORD" placeholders in the HTML string with values from the map. However, this doesn't happen because the replace() method doesn't modify the existing string. Instead, it creates a new string with the replacements made.

To solve this issue, you need to assign the new string to the html variable:

html = html.replace(delimiter + entry.getKey()+ delimiter, entry.getValue());

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By doing this, you'll create a new string that includes the replacements and assign it to the html reference. This way, the changes will be reflected in the original html string.

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