Check the collection contract before tracing the handler.
Review indexed removal, set uniqueness, map replacement, unmodifiable lists, parsing exceptions and catch order.
The count records matching keys among these six selected Java 25 tasks. It is not a developer level, percentile, hiring cutoff or qualification. Every explanation and this full revision guide remain available at every count.
Six explicit collection and failure outcomes
These tasks use a mutable ArrayList, a set’s size, a map’s single-key value, a factory-created unmodifiable list and two small exception examples. They distinguish an operation that succeeds, an operation that throws and is handled, and a program that cannot compile. Only deterministic output is requested. The set is not printed in an assumed order, and the map task does not depend on its iteration order or an implementation’s internal layout.
Change a map value without adding another key
For a fresh unscored example, place gate→3 in a Map<String,Integer>, then put gate→8. Looking up gate gives eight, and the map has one mapping. A map associates one current value with an equal key; it does not accumulate every past value unless you deliberately store a collection as that value. This is why a size result and a returned value answer different questions. Write both when tracing a replacement, rather than inferring size from how many put calls you saw.
Read the declared operation and collection type
An int argument to remove selects the indexed List operation in this bank, and indexes start at zero. A Set rejects duplicate equal elements, so repeated equal strings do not each add to its size. List.of creates an unmodifiable list, while copying those elements into a new ArrayList creates a different structure that can be changed. None of those statements promises deep immutability of every contained object or a universal policy about null for every collection implementation.
Distinguish compile-time rejection from a caught failure
In the parsing example, Integer.parseInt receives text that is not a decimal integer. It throws before a numeric result reaches print; a matching catch prints the chosen label, and the normally reached finally adds its suffix. The broad-catch-first example is rejected because a later subtype catch is already covered. It never reaches runtime handler selection. Read the stage and the exact exception class before selecting an outcome, rather than treating every failure as an uncaught crash.
Predict the size, value and failure separately
Make a disposable Java 25 program with invented short labels. First predict a list’s contents after one indexed removal, then a set’s size after a duplicate add, then a map’s value after replacement. In a separate small program, catch one expected parsing exception and print a marker from finally. Keep these examples separate so one failure does not hide all later outputs. The site requires no file upload and does not execute visitor code; this routine is optional practice in your own environment.
Use an explanation to locate the violated contract
When an answer differs, name the exact assumption: index versus element value, uniqueness versus count of add attempts, replacement versus accumulation, modifiable versus unmodifiable structure, or compilation versus runtime handling. The six-task count can guide which explanation to revisit, but it does not audit exception safety in a production system. A perfect result does not demonstrate concurrent collection design, resource management or the ability to recover user data after a real failure.
A fixed practice bank remains a limited sample
All selected answers, keys and complete explanations appear after the 24 valid choices, with every revision guide available regardless of correct count. There are no expert bands, job matches, time rewards or certification claims. The snippets are independently authored and compiler checked against the stated Java 25 environment, rather than copied from a proprietary employer screen. Repeating the same bank after studying the answers can reflect memory. Use a new miniature program when exploring whether you can apply the distinction elsewhere.