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String.format Locale Bug: Why “1234,50” Throws NumberFormatException on Android

October 9, 2026 by Arsam
Calculator on euro banknotes, illustrating a String.format locale bug in an Android checkout amount

A String.format locale bug turns 1234.50 into 1234,50 or Arabic digits, so toDouble() throws NumberFormatException. Runnable repro, fix and interview answer.

Categories Bug-Squash Interview, Java Interview Tags android, debugging-interview, interview-prep, kotlin, localization, technical-interview Leave a comment

Why a Listener That Removes Itself Throws ConcurrentModificationException

October 2, 2026 by Arsam
For loop in syntax-highlighted code on a dark screen, illustrating a listener loop that throws ConcurrentModificationException

Unregistering a listener inside its own callback throws ConcurrentModificationException or skips listeners. Why, JVM vs Android, and the snapshot fix.

Categories Bug-Squash Interview, Java Interview Tags android, interview-prep, java-collections, kotlin, live-coding, technical-interview Leave a comment

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