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Named Placeholders in String Formatting (#12576)

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* Named Placeholders in String Formatting

* assert notEqualTo
This commit is contained in:
Kai Yuan 2022-08-16 02:48:15 +02:00 committed by GitHub
parent c8bb6d7603
commit 8ce82953c5
2 changed files with 78 additions and 0 deletions
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31
core-java-modules/core-java-string-operations-4/src/main/java/com/baeldung/namedformatting/NamedFormatter.java Normal file
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package com.baeldung.namedformatting;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class NamedFormatter {
private NamedFormatter() {}
public static String format(String template, Map<String, Object> parameters) {
StringBuilder newTemplate = new StringBuilder(template);
List<Object> valueList = new ArrayList<>();
Matcher matcher = Pattern.compile("[$][{](\\w+)}").matcher(template);
while (matcher.find()) {
String key = matcher.group(1);
String paramName = "${" + key + "}";
int index = newTemplate.indexOf(paramName);
if (index != -1) {
newTemplate.replace(index, index + paramName.length(), "%s");
valueList.add(parameters.get(key));
}
}
return String.format(newTemplate.toString(), valueList.toArray());
}
}

47
core-java-modules/core-java-string-operations-4/src/test/java/com/baeldung/namedformatting/NamedFormatterUnitTest.java Normal file
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package com.baeldung.namedformatting;
import org.apache.commons.text.StrSubstitutor;
import org.junit.jupiter.api.Test;
import java.util.HashMap;
import java.util.Map;
import static org.assertj.core.api.Assertions.assertThat;
class NamedFormatterUnitTest {
private static final String TEMPLATE = "Text: [${text}] Number: [${number}] Text again: [${text}]";
@Test
void givenTemplateWithNamedParam_whenCallingCommonsTextStrSubstitutor_shouldGetExpectedResult() {
Map<String, Object> params = new HashMap<>();
params.put("text", "It's awesome!");
params.put("number", 42);
String result = StrSubstitutor.replace(TEMPLATE, params, "${", "}");
assertThat(result).isEqualTo("Text: [It's awesome!] Number: [42] Text again: [It's awesome!]");
}
@Test
void givenTemplateWithNamedParam_whenCallingCommonsTextStrSubstitutorWithParameterNames_shouldNotWorkAsExpected() {
Map<String, Object> params = new HashMap<>();
params.put("text", "'${number}' is a placeholder.");
params.put("number", 42);
String result = StrSubstitutor.replace(TEMPLATE, params, "${", "}");
assertThat(result).isNotEqualTo("Text: ['${number}' is a placeholder.] Number: [42] Text again: ['${number}' is a placeholder.]");
assertThat(result).isEqualTo("Text: ['42' is a placeholder.] Number: [42] Text again: ['42' is a placeholder.]");
}
@Test
void givenTemplateWithNamedParam_whenCallingNamedFormatter_shouldGetExpectedResult() {
Map<String, Object> params = new HashMap<>();
params.put("text", "It's awesome!");
params.put("number", 42);
String result = NamedFormatter.format(TEMPLATE, params);
assertThat(result).isEqualTo("Text: [It's awesome!] Number: [42] Text again: [It's awesome!]");
params.put("text", "'${number}' is a placeholder.");
result = NamedFormatter.format(TEMPLATE, params);
assertThat(result).isEqualTo("Text: ['${number}' is a placeholder.] Number: [42] Text again: ['${number}' is a placeholder.]");
}
}