Guard against the addition of null columns

ctrueden · ctrueden · commit ebcdcce959b2 · 2022-11-02T21:34:58.000-05:00
And add a quick test that the problem is fixed.

This fix prevents cryptic exceptions like this one:

java.lang.NullPointerException: Cannot invoke "org.scijava.table.Column.size()" because "column" is null
    at org.scijava.table.AbstractTable.add(AbstractTable.java:167)
    at org.scijava.table.AbstractTable.add(AbstractTable.java:44)
    at org.scijava.util.SizableArrayList.setSize(SizableArrayList.java:90)
    at org.scijava.table.AbstractTable.setColumnCount(AbstractTable.java:75)
    at org.scijava.table.AbstractTable.&lt;init&gt;(AbstractTable.java:66)
    at org.scijava.table.DefaultFloatTable.&lt;init&gt;(DefaultFloatTable.java:49)

The above exception happens if too many initial columns are given,
because the SizableArrayList under the hood sometimes tries (if a certain
hack fails) to expand the size of the ArrayList by repeatedly adding nulls.

The new test checks that such tables can be created with lots of
initial columns, *and* that we can explicitly add null columns,
without this sort of exception getting thrown.
diff --git a/src/main/java/org/scijava/table/AbstractTable.java b/src/main/java/org/scijava/table/AbstractTable.java
@@ -164,22 +164,22 @@ public void set(final String colHeader, final int row, final T value) {
 
 	@Override
 	public boolean add(final C column) {
-		if (column.size() > rowCount) rowCount = column.size();
+		if (column != null && column.size() > rowCount) rowCount = column.size();
 		scaleColumns();
 		return super.add(column);
 	}
 
 	@Override
 	public void add(final int col, final C column) {
 		super.add(col, column);
-		if (column.size() > rowCount) rowCount = column.size();
+		if (column != null && column.size() > rowCount) rowCount = column.size();
 		scaleColumns();
 	}
 
 	@Override
 	public boolean addAll(final Collection<? extends C> c) {
 		for (final C column : c) {
-			if (column.size() > rowCount) rowCount = column.size();
+			if (column != null && column.size() > rowCount) rowCount = column.size();
 		}
 		scaleColumns();
 		return super.addAll(c);
@@ -188,7 +188,7 @@ public boolean addAll(final Collection<? extends C> c) {
 	@Override
 	public boolean addAll(final int col, final Collection<? extends C> c) {
 		for (final C column : c) {
-			if (column.size() > rowCount) rowCount = column.size();
+			if (column != null && column.size() > rowCount) rowCount = column.size();
 		}
 		scaleColumns();
 		return super.addAll(col, c);
diff --git a/src/test/java/org/scijava/table/DefaultFloatTableTest.java b/src/test/java/org/scijava/table/DefaultFloatTableTest.java
@@ -31,6 +31,8 @@
 package org.scijava.table;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertSame;
 
 import java.util.List;
@@ -304,6 +306,14 @@ public void testInsertRows() {
 		checkTableModifiedRows(table, values, 4, 5);
 	}
 
+	@Test
+	public void testNullColumns() {
+		final FloatTable table = new DefaultFloatTable(100, 10);
+		table.add(null);
+		assertNotNull(table.get(99));
+		assertNull(table.get(100));
+	}
+
 	// TODO - Add more tests.
 
 	// -- Helper methods --
