I have a String that is coming from an API or stored in my database, and I want to replace all tags with my tags at runtime. Is there any efficient way to achieve this?
Using if else is not efficient, since my model has more than 100 fields.
String rawText= "Hello %name% !, Nice to meet you! Your age is %age%."
I want replace all %____% text with my value stored in my Model.
class Person{
private String name;
private String age;
getter...
setter....
}
You can use reflection to get the field values by name:
class Person {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public String replaceTags(String rawText) {
Matcher m = Pattern.compile("%(.+?)%").matcher(rawText);
boolean result = m.find();
if (result) {
StringBuffer sb = new StringBuffer();
do {
m.appendReplacement(sb, Matcher.quoteReplacement(getField(m.group(1))));
result = m.find();
} while (result);
m.appendTail(sb);
return sb.toString();
}
return rawText.toString();
}
private String getField(String name) {
try {
return String.valueOf(this.getClass().getDeclaredField(name).get(this));
} catch (Exception e) {
throw new IllegalArgumentException("could not read value for field: " + name);
}
}
}
If you're on Java 9, you can simplify replaceTags() with a replacement function:
public String replaceTags(String rawText) {
return Pattern.compile("%(.+?)%").matcher(rawText)
.replaceAll(r -> Matcher.quoteReplacement(getField(r.group(1))));
}
If you have a JSON serialization library like Jackson, you can use it to handle the reflection automatically and build a map of values by field name:
Map<String, Object> fieldValues = new ObjectMapper()
.convertValue(this, new TypeReference<Map<String, Object>>() {});
Using Reflection You can do it with few lines of code :
import java.lang.reflect.Field;
public class Main {
public static void main(String arg[]) throws ClassNotFoundException, IllegalArgumentException, IllegalAccessException {
String rawText= "Hello %name% !, Nice to meet you! Your age is %age%.";
Field[] fields = Person.class.getFields();
Person person = new Person("TestName", "TestAge");
for(Field field: fields) {
rawText = rawText.replace("%"+field.getName()+"%", (String)field.get(person));
}
}
}
Just make the fields public in Person class.
String.replace() instead.
a$ is a valid field name. See what happens if you try replacing it as regex.you can use replaceAll
String rawText= "Hello %name% !, Nice to meet you! Your age is %age%.";
rawText = rawText.replaceAll("%name%", "new name");
rawText = rawText.replaceAll("%age%", "new age");
where the new name and new age can come from your model.
replace() unless you need regex.
I don't see any reason why regular string concatenation would not be sufficient here. Just define a helper method inside Person which builds the output string using the properties of a given person:
public class Person {
// ...
public String getGreeting() {
StringBuilder sb = new StringBuilder("");
sb.append("Hello ").append(name).append(", nice to meet you! Your age is ");
sb.append(age).append(".");
return sb.toString();
}
}
