cloning, equals() - not understanding the behaviour

[Jan Groth]

good evening from germany,

i have a situation like this:

a data class:

...
public readRecord(long recNo) {
Record rec = _dataFactory.read(recNo);
return (String[]) rec.getValues().clone()
...

a test class:

  
String[] record = Data.readRecord(1);
String[] recordClone = (String[]) record.clone()
...
some test logic with record
...
record = recordClone;
assertTrue(Data.readRecord(1).equals(recordClone);

the test fails at the last line.

okay, first guess, easy: Data.readRecord(1) returns something else, that's the failure. but check this:

this is the output of my runtime debugger:

Data.readRecord(1)[0].equals(recordClone[0])    --> true
Data.readRecord(1)[1].equals(recordClone[1])    --> true
Data.readRecord(1)[2].equals(recordClone[2])    --> true
Data.readRecord(1)[3].equals(recordClone[3])    --> true
Data.readRecord(1)[4].equals(recordClone[4])    --> true
Data.readRecord(1)[5].equals(recordClone[5])    --> true
Data.readRecord(1).length --> 6
recordClone.length --> 6

my question:
if the two string arrays are equal on a line-by-line base, and have the same length, why does the direct equal() return true?

and idea appreciated,

thank you very much,

Jan

[Jan Groth]

stupid me, the question is:

if the two string arrays are equal on a line-by-line base, and have the same length, why does the direct equal() return false?

******

i would really appreciate a preview functionality in this forum...

[Ernest Friedman-Hill]

Because arrays don't override the "equals" method. Interestingly enough, someone just raised this very question over in the Java in General (Advanced) forum; see that thread for a more detailed answer.

There's a family of overloaded two-argument static methods named java.util.Arrays.equals() which you can use to compare arrays elementwise.

[Jan Groth]

perfect answer, thanks a lot!