Added pattern string replacement example

Author: botenbreuk

src/main/java/nl/rdb/java_examples/string/StringExample.java

@@ -1,11 +1,18 @@
 package nl.rdb.java_examples.string;
 
+import java.util.HashMap;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
 import lombok.extern.slf4j.Slf4j;
 import nl.rdb.java_examples.scanner.Example;
 
 @Slf4j
 public class StringExample {
 
+    private static final Pattern PATTERN = Pattern.compile("\\{([^}]+)}");
+
     @Example
     void generateExample() {
         log.info(new CodeGenerator().getCode());
@@ -31,4 +38,66 @@ void replace() {
         log.info("{}", test.replace(".", "Test-"));
         log.info("{}", test.replaceAll("\\.", "Test-"));
     }
+
+    @Example
+    void replacePlaceHolders() {
+        String urlTemplate = "http://localhost/test/{id}/test/{id2}";
+
+        Map<String, String> params = new HashMap<>();
+        params.put("id", "12345");
+        params.put("id2", "user-profile");
+
+        log.info("Original URL Template: {}", urlTemplate);
+        log.info("User Variables: {}", params);
+
+        try {
+            String finalUrl = replace(urlTemplate, params);
+            log.info("Final URL: {}", finalUrl);
+        } catch (IllegalArgumentException e) {
+            // Log the error with the exception message.
+            log.error("Error replacing placeholders: {}", e.getMessage());
+        }
+    }
+
+    @Example
+    void replacePlaceHoldersMissingPlaceholder() {
+        String urlTemplate = "http://localhost/test/{id}/test/{id2}";
+
+        Map<String, String> params = new HashMap<>();
+        params.put("id", "12345");
+        params.put("id2", "user-profile");
+
+        Map<String, String> incompleteVariables = new HashMap<>();
+        incompleteVariables.put("id", "987");
+
+        log.info("Original URL Template: {}", urlTemplate);
+        log.info("Incomplete Variables: {}", incompleteVariables);
+
+        try {
+            String finalUrl = replace(urlTemplate, incompleteVariables);
+            log.info("Final URL: {}", finalUrl);
+        } catch (IllegalArgumentException e) {
+            // It's good practice to also log the exception object itself for a full stack trace
+            log.error("Error replacing placeholders: {}", e.getMessage(), e);
+        }
+    }
+
+    private String replace(String template, Map<String, String> variables) {
+        Matcher matcher = PATTERN.matcher(template);
+        StringBuilder resultBuilder = new StringBuilder();
+
+        while (matcher.find()) {
+            String placeholderName = matcher.group(1);
+            String replacement = variables.get(placeholderName);
+
+            if (replacement == null) {
+                throw new IllegalArgumentException("No value found for placeholder: %s".formatted(matcher.group(0)));
+            }
+
+            matcher.appendReplacement(resultBuilder, replacement);
+        }
+
+        matcher.appendTail(resultBuilder);
+        return resultBuilder.toString();
+    }
 }