Java Tutorial/Log/Log Filter

Custom filter

import java.util.logging.Filter;
import java.util.logging.Level;
import java.util.logging.LogRecord;
import java.util.logging.Logger;
class Person {
  private String name = null;
  private int age;
  public Person(String name, int age) {
    this.name = name;
    this.age = age;
  }
  public void setName(String name) {
    this.name = name;
  }
  public String getName() {
    return name;
  }
  public void setAge(int age) {
    this.age = age;
  }
  public int getAge() {
    return age;
  }
}
class AgeFilter implements Filter {
  public boolean isLoggable(LogRecord record) {
    boolean result = false;
    Object[] objs = record.getParameters();
    Person person = (Person) objs[0];
    if (person != null) {
      int age = person.getAge();
      if (age > 30)
        result = true;
      else
        result = false;
    }
    return result;
  }
}
public class Main {
  public static void main(String args[]) {
    Logger logger = Logger.getLogger("your.logging");
    AgeFilter filter = new AgeFilter();
    logger.setFilter(filter);
    Person person = new Person("YourName", 32);
    logger.log(Level.INFO, "Person has age " + person.getAge(), person);
  }
}

Setting a Filter on a Logger Handler

import java.util.logging.ConsoleHandler;
import java.util.logging.Filter;
import java.util.logging.LogRecord;
import java.util.logging.Logger;
public class Main {
  public static void main(String[] argv) throws Exception {
    ConsoleHandler handler = new ConsoleHandler();
    handler.setFilter(new Filter() {
      public boolean isLoggable(LogRecord record) {
       return true;
      }
    });
    // Add the handler to a logger
    Logger logger = Logger.getLogger("com.mycompany");
    logger.addHandler(handler);
  }
}

Simple filter

import java.util.logging.Filter;
import java.util.logging.Level;
import java.util.logging.LogRecord;
import java.util.logging.Logger;
public class MainClass {
  private static Logger logger = Logger.getLogger("SimpleFilter");
  static class A {
  };
  static class B {
  };
  static void sendLogMessages() {
    logger.log(Level.WARNING, "message 1!", new A());
    logger.log(Level.WARNING, "message 2!", new B());
  }
  public static void main(String[] args) {
    sendLogMessages();
    logger.setFilter(new Filter() {
      public boolean isLoggable(LogRecord record) {
        Object[] params = record.getParameters();
        if (params == null)
          return true;
        if (record.getParameters()[0] instanceof A)
          return true;
        return false;
      }
    });
    logger.info("After setting filter..");
    sendLogMessages();
  }
}