Letter.java
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public class Letter {
  public final double XHEIGHT = 6;
  public final double DEFAULT_DEPTH = 0;
  public String letter;
  private double size;
  public double height;
  public double depth;

  public Letter( String inputLetter ) {
    this.letter = inputLetter;
    this.height = XHEIGHT;
    this.depth = DEFAULT_DEPTH;
  }

  public void setHeight( double newHeight ) {
    this.height = newHeight;
  }

  public void setDepth( double newDepth ) {
    this.depth = newDepth;
  }

  public void calculateSize( ) {
    size = height + depth;
  }
}
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lowerCase.java
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public class lowerCase extends Letter {

  public lowerCase( String inputLetter ) {
    inputLetter = inputLetter.toLowerCase( );
    this.letter = inputLetter;
    this.height = XHEIGHT;
    this.depth = DEFAULT_DEPTH;
  }

}