Stream merge: Difference between revisions
Added Java
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Line 1,035:
See implementation in https://github.com/bgamari/pipes-interleave/blob/master/Pipes/Interleave.hs
=={{header|Java}}==
<lang Java>import java.util.Iterator;
import java.util.List;
import java.util.Objects;
public class StreamMerge {
private static <T extends Comparable<T>> void merge2(Iterator<T> i1, Iterator<T> i2) {
T a = null, b = null;
while (i1.hasNext() || i2.hasNext()) {
if (null == a && i1.hasNext()) {
a = i1.next();
}
if (null == b && i2.hasNext()) {
b = i2.next();
}
if (null != a) {
if (null != b) {
if (a.compareTo(b) < 0) {
System.out.print(a);
a = null;
} else {
System.out.print(b);
b = null;
}
} else {
System.out.print(a);
a = null;
}
} else if (null != b) {
System.out.print(b);
b = null;
}
}
if (null != a) {
System.out.print(a);
}
if (null != b) {
System.out.print(b);
}
}
@SuppressWarnings("unchecked")
@SafeVarargs
private static <T extends Comparable<T>> void mergeN(Iterator<T>... iter) {
Objects.requireNonNull(iter);
if (iter.length == 0) {
throw new IllegalArgumentException("Must have at least one iterator");
}
Object[] pa = new Object[iter.length];
boolean done;
do {
done = true;
for (int i = 0; i < iter.length; i++) {
Iterator<T> t = iter[i];
if (null == pa[i] && t.hasNext()) {
pa[i] = t.next();
}
}
T min = null;
int idx = -1;
for (int i = 0; i < pa.length; ++i) {
T t = (T) pa[i];
if (null != t) {
if (null == min) {
min = t;
idx = i;
done = false;
} else if (t.compareTo(min) < 0) {
min = t;
idx = i;
done = false;
}
}
}
if (idx != -1) {
System.out.print(min);
pa[idx] = null;
}
} while (!done);
}
public static void main(String[] args) {
List<Integer> l1 = List.of(1, 4, 7, 10);
List<Integer> l2 = List.of(2, 5, 8, 11);
List<Integer> l3 = List.of(3, 6, 9, 12);
merge2(l1.iterator(), l2.iterator());
System.out.println();
mergeN(l1.iterator(), l2.iterator(), l3.iterator());
System.out.println();
System.out.flush();
}
}</lang>
{{out}}
<pre>1245781011
123456789101112</pre>
=={{header|Perl}}==
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