src/java/org/apache/lucene/index/TermEnum.java

package org.apache.lucene.index;

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import java.io.IOException;

/** Abstract class for enumerating terms.

  <p>Term enumerations are always ordered by Term.compareTo().  Each term in
  the enumeration is greater than all that precede it.  */

public abstract class TermEnum {
  /** Increments the enumeration to the next element.  True if one exists.*/
  abstract public boolean next() throws IOException;

  /** Returns the current Term in the enumeration.
    Initially invalid, valid after next() called for the first time.*/
  abstract public Term term();

  /** Returns the docFreq of the current Term in the enumeration.
    Initially invalid, valid after next() called for the first time.*/
  abstract public int docFreq();

  /** Closes the enumeration to further activity, freeing resources. */
  abstract public void close() throws IOException;
}