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Guava Repeat Duplicate Key Exception IllegalArgumentException

Here's a quick cut off.

Map<String, String> map = new HashMap<String, String>(); map.put("1", "1"); map.put("2", "1"); Ordering<String> valueComparator = Ordering.from(String.CASE_INSENSITIVE_ORDER).onResultOf(Functions.forMap(map)); Map<String, String> sortedMap = ImmutableSortedMap.copyOf(map, valueComparator);

When I run it, I get this exception.

 java.lang.IllegalArgumentException: Duplicate keys in mappings 2=1 and 1=1 at com.google.common.collect.ImmutableSortedMap.validateEntries(ImmutableSortedMap.java:304) at com.google.common.collect.ImmutableSortedMap.copyOfInternal(ImmutableSortedMap.java:281) at com.google.common.collect.ImmutableSortedMap.copyOf(ImmutableSortedMap.java:220) at com.dbs.datasource.TestBeans.test(TestBeans.java:90) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at junit.framework.TestCase.runTest(TestCase.java:168) at junit.framework.TestCase.runBare(TestCase.java:134) at org.springframework.test.ConditionalTestCase.runBare(ConditionalTestCase.java:76) at junit.framework.TestResult$1.protect(TestResult.java:110) at junit.framework.TestResult.runProtected(TestResult.java:128) at junit.framework.TestResult.run(TestResult.java:113) at junit.framework.TestCase.run(TestCase.java:124) at junit.framework.TestSuite.runTest(TestSuite.java:243) at junit.framework.TestSuite.run(TestSuite.java:238) at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:83) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

It seems like it is changing the key and value somewhere. Using guava-14.0-rc1.jar

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1 answer

It does exactly what you ask for - arranging the entries by the value associated with the key. I assume that you are aware of this part, given that you called the valueComparator variable.

So, your two keys are equal depending on the comparator used - and therefore it throws a documented exception:

IllegalArgumentException - if any two keys are equal according to the comparator

Perhaps you want to order by value and then by key to ensure uniqueness?

 Ordering<String> valueThenKeyComparator = Ordering.from(String.CASE_INSENSITIVE_ORDER) .onResultOf(Functions.forMap(map)) .compound(Ordering.<String> natural());
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