It's a shame you'be been downvoted even while being correct - I gave you one upvote at least.
Decompile is irrelevant here, the only difference is 'str1' might have been named something different in the original code.
This is java code, so "string" != "string" will usually return true always, as you are checking if the objects are equal and not whether the contents are equal. Depending on the JRE this code runs on, it would give different output. [1]
I believe String literals are guaranteed to be == in the same source file by the spec, although it's been some years since I could quote chapter and verse for that.
You are correct (albeit substituting "class" for "source file" since runtime Java has no concept of source files), although the guarantee is stronger than that. Any two identical literals will refer to the same object, since literals are interned, regardless of what classes "own" them.
The OP is still correct though - don't use == for strings, always use .equals()
The problem with using == is maintainability and silent failure. Someone may change the program to accept the string from the command line, or just about anything else. As soon as this happens, a string can come in from elsewhere and still have the value "yes" but would still pass the inequality.
This bug would be completely silent and incredibly difficult to debug, possibly only arising in strange and unusual circumstances. The only way to really avoid this is to just use .equals() always. Using == for strings in Java is plain terrible coding, and the OP is therefore correct.
Decompile is irrelevant here, the only difference is 'str1' might have been named something different in the original code.
This is java code, so "string" != "string" will usually return true always, as you are checking if the objects are equal and not whether the contents are equal. Depending on the JRE this code runs on, it would give different output. [1]
[1] http://stackoverflow.com/questions/513832/how-do-i-compare-s...