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package edu.rice.cs.util;
import java.io.File;
import java.io.Serializable;

/** A null file.  This class is NOT a singleton because we need multiple, distinct null files for untitled documents. 
  * The equals method is overridden so that distinct NullFile objects (which all have the same path) are unequal. 
  */
public class NullFile extends File implements Serializable {
  
  private static volatile int ct = 0;

  public NullFile() { 
    this("*NullFile<" + ct + ">"); 
    ct++;
  }
  
  private NullFile(String lexiName) {
    super(lexiName);
  }
  
  /* The following two methods hide the fact that the name field of this file has the form "*NullFile<ct>".  They can
   * be commented out for debugging purposes. */
  public String toString() { return "(Untitled)"; }
  public String getName() { return "(Untitled)"; }
  
  public String getLexiName() { return ""; }
  
  /**  All distinct objects of type NullFile are unequal. */
  public boolean equals(Object o) { return o == this; } 
}