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fix: #158: ClassCastException in ComponentReportQuery.addZeroLengthArrays #165

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Merged
jasonk000 merged 1 commit into from
Mar 2, 2026
Merged

fix: #158: ClassCastException in ComponentReportQuery.addZeroLengthArrays #165

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4 changes: 2 additions & 2 deletions ...s/org.eclipse.mat.api/src/org/eclipse/mat/inspections/component/ComponentReportQuery.java
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Original file line number Diff line number Diff line change
Expand Up @@ -795,8 +795,8 @@ private void addZeroLengthArrays(SectionSpec componentReport, long totalSize, Hi
long size = Math.abs((Long) refinedTable.getColumnValue(row, 4));
if (size > threshold)
{
int numberOfObjects = (Integer) refinedTable.getColumnValue(row, 1);
String retainedSize = refinedTable.getFormattedColumnValue(row, 3);
int numberOfObjects = (Integer) refinedTable.getColumnValue(row, 2);
String retainedSize = refinedTable.getFormattedColumnValue(row, 4);

if (comment.length() == 0)
{
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33 changes: 33 additions & 0 deletions plugins/org.eclipse.mat.tests/src/org/eclipse/mat/tests/snapshot/QueriesTest.java
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Expand Up @@ -1611,4 +1611,37 @@ public void testSecondarySnapshot() throws SnapshotException, IOException
if (cls != null)
assertThat("Expect snapshot disposed so no classes", cls.size(), equalTo(0));
}

/**
* Regression test for issue #158: ClassCastException in addZeroLengthArrays.
* ArraysBySizeQuery groups by two keys (array length and single-instance size),
* so column 1 is the single-instance size (Long), not the count.
* The count is at column 2 (Integer). This test pins the column contract so
* that a layout change in ArraysBySizeQuery will be caught before it silently
* breaks ComponentReportQuery.addZeroLengthArrays.
*/
@Test
public void testArraysBySizeColumnTypes() throws SnapshotException
{
Collection<IClass> classes = snapshot.getClassesByName("byte[]", false);
assertNotNull(classes);
assertFalse(classes.isEmpty());
int[] objectIds = classes.iterator().next().getObjectIds();
assertTrue(objectIds.length > 0);

RefinedResultBuilder builder = SnapshotQuery.lookup("arrays_grouped_by_size", snapshot)
.setArgument("objects", objectIds)
.refine(new VoidProgressListener());
builder.setInlineRetainedSizeCalculation(true);
RefinedTable table = (RefinedTable) builder.build();

assertTrue(table.getRowCount() > 0);
Object row = table.getRow(0);
assertThat("col 0 (array length key) must be Integer",
table.getColumnValue(row, 0), instanceOf(Integer.class));
assertThat("col 1 (single-instance size key) must not be Integer - it is Long",
table.getColumnValue(row, 1), not(instanceOf(Integer.class)));
assertThat("col 2 (count) must be Integer",
table.getColumnValue(row, 2), instanceOf(Integer.class));
}
}