Added the things that the added the things.

The things.

arrays/src/arrays/Main.java

@@ -1,15 +1,63 @@
 package arrays;
 
 import java.util.Iterator;
+import java.util.Queue;
 import tester.Tester;
 
 class Sieve implements Iterator<Integer> {
+    int cur;             // The current number.
+    int lim;             // The largest number to check.
+    boolean[] isntPrime; // Where true, not a prime.
 
-    public boolean hasNext() { return false; }
+    Sieve(int lim) {
+        if (lim < 2)
+            throw new UnsupportedOperationException(
+                "Can't find primes less than 2."
+            );
 
-    public Integer next() { return null; }
+        this.cur = 2; // Start with 2.
+        this.lim = lim;
+        this.isntPrime = new boolean[lim + 1];
+
+        this.isntPrime[3] = true;
+
+        /*
+        for (int i = this.cur; i <= this.lim; i += this.cur) {
+            this.isntPrime[i] = true;
+        }
+
+        for (int i = this.cur; !this.isntPrime[i]; i++) {}
+        */
+    }
+
+    // [ false false false false false false false ]
+    // [ 1     2     3     4     5     6     7 ]
+    //
+    // [ false false false false false false false ]
+    // [ 1     2     3     4     5     6     7 ]
+
+    public boolean hasNext() { return true; }
+
+    public Integer next() {
+        while (this.isntPrime[this.cur]) this.cur++;
+        return this.cur;
+    }
 }
 
 class Examples {
-    Iterator<Integer> i = new Sieve();
+    void testSieve(Tester t) {
+        Sieve sieve = new Sieve(10);
+        t.checkExpect(sieve.hasNext(), true);
+        t.checkExpect(sieve.next(), 2);
+        t.checkExpect(sieve.next(), 3);
+        t.checkExpect(sieve.next(), 5);
+        t.checkExpect(sieve.next(), 7);
+        t.checkExpect(sieve.next(), 11);
+        t.checkExpect(sieve.next(), 13);
+        t.checkExpect(sieve.next(), 17);
+        t.checkExpect(sieve.next(), 19);
+        t.checkExpect(sieve.next(), 23);
+        t.checkExpect(sieve.next(), 29);
+        t.checkExpect(sieve.next(), false);
+    }
 }