Adding equals implementation macro in Eclipse

In order to create new macro for Java equals implementation in Eclipse follow these steps (I have Eclipse 3.4 but steps should be similar for older versions also):

  • go to Preferences > "Java > Editor > Templates
  • Choose "New..." and enter following values:
    Name equals
    Description Default equals implementation
    Pattern 
    public boolean equals(Object obj) {
  if (this == obj) {
  	return true;
  }

  if (!(obj instanceof ${enclosing_type})) {
    return false;
  }
  ${enclosing_type} other = (${enclosing_type}) obj;
   
  //TODO finish equals
  throw new UnsupportedOperationException("Equals for ${enclosing_type} is not implemented");
}

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Comments (3)

 

  1. Aug 07, 2008

    Sven Filatov says:

    If you usually have commons-lang library included in your projects, then this mi...

    If you usually have commons-lang library included in your projects, then this might be useful as well:

    public boolean equals(Object obj) {
  if (this == obj) {
    return true;
  }
  
  if (!(obj instanceof ${enclosing_type})) {
    return false;
  }
  ${enclosing_type} other = (${enclosing_type}) obj;
  
  //TODO finish equals by adding more append() calls
  return new EqualsBuilder()
      .append(${getter:field}, other.${getter:field})
      ${cursor}
      .isEquals();
}

    And similar templates for hashCode() and toString() using HashCodeBuilder and ToStringBuilder as well.

    There's also trivial versions of the three methods possible:

    public boolean equals(Object obj) {
  return EqualsBuilder.reflectionEquals(this, obj, new String[] { "id" });
}

public int hashCode() {
  return HashCodeBuilder.reflectionHashCode(this, new String[] { "id" });
}

public String toString() {
  return ToStringBuilder.reflectionToString(this);
}

    But I wouldn't recommend this because usually there's at least one field you don't want to appear in equals() and hashCode(), and by specifying such field(s) you would lose refactoring support.

    1. Aug 07, 2008

      Sven Filatov says:

      For completeness' sake, here's the template for hashCode(): public int hashCod...

      For completeness' sake, here's the template for hashCode():

      public int hashCode() {
  //TODO finish hashCode by adding more append() calls
  return new HashCodeBuilder()
      .append(${getter:field})
      ${cursor}
      .toHashCode();
}

      And template for toString():

      public String toString() {
  //TODO finish toString by adding more append() calls
  return new ToStringBuilder(this)
      .append(${getter:field})
      ${cursor}
      .toString();
}

      1. Oct 09, 2008

        Anonymous says:

        You can also add a template for an import statement of the respective *Build...

        You can also add a template for an import statement of the respective *Builder.
        For instance:

        ${:import(org.apache.commons.lang.builder.EqualsBuilder)}

        which evaluates to nothing but adds an import statement if needed.