Example.java

import java.util.concurrent.TimeUnit;

public final class TestClass {

    public static final String LOREM_IPSUM = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. " +
            "In in pellentesque sem, quis iaculis sapien. Quisque ut velit vel ex facilisis euismod in et " +
            "neque. Donec eget ex in nisl dapibus congue id ultricies odio. Nulla et nibh nec nunc pretium aliquet " +
            "in quis augue. Aenean sit amet nisi eu tortor malesuada tincidunt. Fusce in pulvinar sapien, vitae mollis orci. " +
            "Donec sed purus luctus, convallis metus sit amet, volutpat turpis. Sed quis nunc id nisl fringilla tincidunt a ut urna.";

    public static void main(String[] args) throws InterruptedException {
        Marquee marquee = Marquee.newMarquee()
                .text(LOREM_IPSUM) // the text we want to scroll
                .limit(32)         // The character limit to display
                .interval(500, TimeUnit.MILLISECONDS)   // The update interval
                .create();

        for (String text : marquee) {
            System.out.println('\r' + text);
            // This will constantly be rewriting the line, and not look nice.
            // To fix this, we sleep for a few hundred milliseconds
            Thread.sleep(250);
        }
    }

}

Marquee.java

import com.google.common.base.Preconditions;

import javax.annotation.Nonnull;
import java.util.Iterator;
import java.util.concurrent.TimeUnit;

public final class Marquee implements Iterator<String>, Iterable<String> {

    public interface Factory {
        @Nonnull
        Marquee create();
    }

    private String text;
    private int limit;
    private long interval;

    private String currentText;
    private int currentIndex;
    private long lastSent;

    private Marquee(String text, int limit, long interval) {
        this.text = text;
        this.limit = limit;
        this.interval = interval;
    }

    @Override
    public boolean hasNext() {
        return true;
    }

    @Override
    public String next() {

        if (this.text.length() - 1 <= limit) {
            return this.text;
        } else {

            // only update the current text if the time has passed.
            if  (System.nanoTime() >= lastSent + interval || lastSent <= 0) {

                if (this.currentIndex >= this.text.length() - 1) {
                    this.currentIndex = 0;
                }

                int finalLimit = Math.min(this.currentIndex + limit, this.text.length());

                if (finalLimit <= this.text.length()) {

                    if (finalLimit == this.text.length()) {
                        int diff = (this.currentIndex + limit) - this.text.length();

                        String endText = text.substring(this.currentIndex, finalLimit);
                        String startText = text.substring(0, diff);

                        this.currentText = String.valueOf(endText + " " + startText).substring(0, limit);

                    } else {
                        this.currentText = text.substring(this.currentIndex, finalLimit);
                    }

                }
                this.currentIndex++;

                if (this.interval > 0) {
                    this.lastSent = System.nanoTime();
                }
            }

            return this.currentText;
        }
    }


    @Override
    @Nonnull
    public Iterator<String> iterator() {
        return this;
    }


    @Nonnull
    public static Builder newMarquee() {
        return new Builder();
    }

    public static final class Builder implements Factory {

        private String text;
        private int limit;
        private long interval;

        public Builder text(String text) {
            Preconditions.checkArgument(text != null && !text.isEmpty(), "text cannot be null or empty!");

            this.text = text;

            return this;
        }

        public Builder limit(int limit) {
            Preconditions.checkArgument(limit >= 16 && limit <= 32, "limit not in range (must be between 16 & 32)!");

            this.limit = limit;

            return this;
        }

        public Builder interval(long time, TimeUnit unit) {
            this.interval = unit.toNanos(time);
            return this;
        }

        @Override
        @Nonnull
        public Marquee create() {
            return new Marquee(this.text, this.limit, this.interval);
        }
    }
}