*
   * @param line the line read from the input, without delimiter
   * @return true to continue processing, false to stop
   */
  @CanIgnoreReturnValue // some uses know that their processor never returns false
  boolean processLine(String line) throws IOException;

  /** Return the result of processing all the lines. */
  @ParametricNullness
  T getResult();

          int seen;

          @Override
          public boolean processLine(String line) {
            seen++;
            return false;
          }

          @Override
          public Integer getResult() {
            return seen;
          }
        };
    assertEquals(
        "processLine was called more than once",
        1,
        CharStreams.readLines(r, alwaysFalse).intValue());

          int seen;

          @Override
          public boolean processLine(String line) {
            seen++;
            return false;
          }

          @Override
          public Integer getResult() {
            return seen;
          }
        };
    assertEquals(
        "processLine was called more than once",
        1,
        CharStreams.readLines(r, alwaysFalse).intValue());

    List<String> list =
        source.readLines(
            new LineProcessor<List<String>>() {
              List<String> list = Lists.newArrayList();

              @Override
              public boolean processLine(String line) throws IOException {
                list.add(line);
                return true;
              }

              @Override
              public List<String> getResult() {

    List<String> list =
        lines.readLines(
            new LineProcessor<List<String>>() {
              List<String> list = Lists.newArrayList();

              @Override
              public boolean processLine(String line) throws IOException {
                list.add(line);
                return true;
              }

              @Override
              public List<String> getResult() {

    List<String> list =
        source.readLines(
            new LineProcessor<List<String>>() {
              List<String> list = Lists.newArrayList();

              @Override
              public boolean processLine(String line) throws IOException {
                list.add(line);
                return true;
              }

              @Override
              public List<String> getResult() {

    List<String> list =
        lines.readLines(
            new LineProcessor<List<String>>() {
              List<String> list = Lists.newArrayList();

              @Override
              public boolean processLine(String line) throws IOException {
                list.add(line);
                return true;
              }

              @Override
              public List<String> getResult() {

    LineProcessor<List<String>> collectAndLowercaseAndTrim =
        new LineProcessor<List<String>>() {
          List<String> collector = new ArrayList<>();

          @Override
          public boolean processLine(String line) {
            collector.add(whitespace().trimFrom(line));
            return true;
          }

          @Override
          public List<String> getResult() {
            return collector;

    LineProcessor<List<String>> collectAndLowercaseAndTrim =
        new LineProcessor<List<String>>() {
          List<String> collector = new ArrayList<>();

          @Override
          public boolean processLine(String line) {
            collector.add(whitespace().trimFrom(line));
            return true;
          }

          @Override
          public List<String> getResult() {
            return collector;

    LineProcessor<List<String>> collect =
        new LineProcessor<List<String>>() {
          List<String> collector = new ArrayList<>();

          @Override
          public boolean processLine(String line) {
            collector.add(line);
            return true;
          }

          @Override
          public List<String> getResult() {
            return collector;
          }