Wednesday, 3 May 2017

This week 8/2017

In this post I will write two small tips.

Slf4J - has one handy feature. One interface solves two problems:
1) firstly it check if message will be used, then transform parameters to String type and build all message,
2) helps to have clean code without concatenation of parameters

LOGGER.debug("Test message {} {} {}{}{}{}{}{}{}", 3, "+", 3, =, null, " 6");

Earlier I use to check logging level manually and use to format messages by String::printf


Lombok - builder pattern is great pattern to create immutable value object with many attributes. Lombok does it for you, you have only to add @Builder annotation. Unfortunately it has other standard of calling setter method (there is no set prefix) and it is useless to create builder for inheritance’s class.

Bellow I compare simple class with lombok annotations and equivalent to it. 
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import lombok.Builder;
import lombok.Data;
import lombok.NonNull;

@Data
@Builder
public class MyLoombok {

 @NonNull
 private final String attr1;

 @NonNull
 private final int attr2;
}


Generated code of builder.
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import lombok.NonNull;

public class MyLoombok {

 @NonNull
 private final String attr1;

 @NonNull
 private final int attr2;

 @java.beans.ConstructorProperties({"attr1", "attr2"})
 MyLoombok(String attr1, int attr2) {
  this.attr1 = attr1;
  this.attr2 = attr2;
 }

 public static MyLoombokBuilder builder() {
  return new MyLoombokBuilder();
 }

 @NonNull
 public String getAttr1() {
  return this.attr1;
 }

 @NonNull
 public int getAttr2() {
  return this.attr2;
 }

 public boolean equals(Object o) {
  if (o == this) return true;
  if (!(o instanceof MyLoombok)) return false;
  final MyLoombok other = (MyLoombok) o;
  if (!other.canEqual((Object) this)) return false;
  final Object this$attr1 = this.getAttr1();
  final Object other$attr1 = other.getAttr1();
  if (this$attr1 == null ? other$attr1 != null : !this$attr1.equals(other$attr1)) return false;
  if (this.getAttr2() != other.getAttr2()) return false;
  return true;
 }

 public int hashCode() {
  final int PRIME = 59;
  int result = 1;
  final Object $attr1 = this.getAttr1();
  result = result * PRIME + ($attr1 == null ? 43 : $attr1.hashCode());
  result = result * PRIME + this.getAttr2();
  return result;
 }

 protected boolean canEqual(Object other) {
  return other instanceof MyLoombok;
 }

 public String toString() {
  return "singleclass.MyLoombok(attr1=" + this.getAttr1() + ", attr2=" + this.getAttr2() + ")";
 }

 public static class MyLoombokBuilder {
  private String attr1;
  private int attr2;

  MyLoombokBuilder() {
  }

  public MyLoombok.MyLoombokBuilder attr1(String attr1) {
   this.attr1 = attr1;
   return this;
  }

  public MyLoombok.MyLoombokBuilder attr2(int attr2) {
   this.attr2 = attr2;
   return this;
  }

  public MyLoombok build() {
   return new MyLoombok(attr1, attr2);
  }

  public String toString() {
   return "singleclass.MyLoombok.MyLoombokBuilder(attr1=" + this.attr1 + ", attr2=" + this.attr2 + ")";
  }
 }
}
Autor: o
Etykiety: , ,

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