XPath to Android UiSelector: can Claude 5.5 replace a converter?

TL;DR

• UiSelector is faster than XPath on Android: it won all 30 benchmark cases. It saved 49 % per lookup at 100 elements and 12 % at 2000 (emulator). Below level 70 of the tree, XPath finds nothing at all.
• 73 % of 1645 real XPath locators convert to a UiSelector. Every converted one ran on an emulator with 0 wrong results; the rest are skipped with a reason. Strict by default; --loose gives simpler, case-insensitive forms.
• Claude 5.5 without rules: 47–63 wrong UiSelectors out of 680 (7–9 %). They look right and often pass a quick check. 65 of the 170 are textContains, which ignores case: wrong by a strict definition, and open to debate. With a rules prompt, Opus and Sonnet made 1 and Haiku 4, and still no model beat the converter.

npx xpath-to-uiselector ./tests          # preview the diff
npx xpath-to-uiselector ./tests --write  # apply it

Or paste your XPaths into the online converter.

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Contents

1. Why leave XPath on Android
2. What a UiSelector is
3. Why converting by hand goes wrong
4. What the converter does
5. How I checked it
6. Claude 5.5 against the converter
   • Is textContains really wrong?
7. Android is harder than iOS
8. The future of UiSelector
9. What I would use
10. Limits

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This is the Android follow-up to my iOS posts. In part 1 I built a converter from XPath to iOS class chain; in part 2 I asked Claude to do the same job. On iOS the best model came within a few points of the converter.

On Android I did both in one go: I built xpath-to-uiselector, then asked Claude Opus, Sonnet and Haiku 5.5 to convert the same locators. Android turned out to be much harder for the models, and the reason is in the API, not in the models.

Why leave XPath on Android

With the Appium UiAutomator2 driver, an XPath lookup first serializes the whole UI tree to XML and then runs the query on it. A UiSelector (the -android uiautomator strategy) walks the live tree and, for findElement, stops at the first match. I measured both in a separate benchmark: 30 cases (10 XPath shapes × 3 targets), each found by both strategies, on screens of 100 to 2000 elements.

• UiSelector won all 30 cases at every size. The saving in milliseconds grows with the tree (22 ms → 133 ms), the saving in percent shrinks (49 % → 12 %).
• The depth limit matters more than the speed. The driver's snapshotMaxDepth is 70: below that, XPath and the page source see nothing. On a chain 100 levels deep, XPath found its last marker at level 66, and UiSelector found every marker down to level 100.
• It is not 10–50× faster. Blog posts often say that, without showing a measurement. I measured 12–49 %: worth having on big screens and in long suites, but not a miracle.

What a UiSelector is

UiSelector is the androidx UiAutomator query builder. Appium takes it as a Java-like string and evaluates it on the device:

XPath	UiSelector
//android.widget.Button	new UiSelector().className("android.widget.Button")
//*[@text="Pay"]	new UiSelector().text("Pay")
//*[@content-desc="Cart"]	new UiSelector().description("Cart")
//*[@resource-id="com.app:id/ok"]	new UiSelector().resourceId("com.app:id/ok")
//*[@checked="true"]	new UiSelector().checked(true)
(//android.widget.EditText)[2]	new UiSelector().className("android.widget.EditText").instance(1)

It has no direct-child or parent step and no position among siblings: childSelector means any descendant, and fromParent searches among the siblings.

Why converting by hand goes wrong

The simple rows above are what everyone converts correctly. The trouble is the methods whose names promise the same thing as XPath but behave differently. All of these were checked on the emulator:

• contains(@text,"Total") → textContains("Total") textContains and textStartsWith ignore case: this also finds "TOTAL". Exact: textMatches("(?s).*Total.*").
• matches(@resource-id,".*\.ok") → resourceIdMatches(".*\\.ok") (in the locator text) The server's string literal unescapes only \", so the regex gets \\., a literal backslash. It matches nothing.
• (//ScrollView//ImageView)[3] → …childSelector(…ImageView.instance(2)) Inside childSelector, instance() counts per container, not across the screen.
• //* → classNameMatches(".*") With classNameMatches, findElements iterates index(i) and loses elements. Exact: new UiSelector().
• //ListView/TextView → …childSelector(…) That is any descendant. UiSelector has no direct child, so there is no exact form.
• ends-with(@text,"USD") → "skip: XPath 2.0" The driver runs XPath 2.0 unless enforceXPath1 is set: matches(), ends-with(), lower-case() all work.

The server accepts all of these: no syntax error, just other elements (or none). The first one is debatable (more on that below), but it changes what the locator finds without anyone noticing: the test passes today and taps another element when someone adds a "TOTAL" label above it.

What the converter does

xpath-to-uiselector scans your test files (Java, Kotlin, Python, JS/TS, C#, Ruby, JSON, YAML), finds the XPath strings and rewrites each one together with its strategy call:

- AppiumBy.xpath("(//android.widget.TextView[@content-desc='price'])[2]")
+ AppiumBy.androidUIAutomator("new UiSelector().className(\"android.widget.TextView\").description(\"price\").instance(1)")

- (AppiumBy.XPATH, '//*[@content-desc="Cart" and contains(@text, "USD")]')
+ (AppiumBy.ANDROID_UIAUTOMATOR, 'new UiSelector().description("Cart").textMatches("(?s).*USD.*")')

[skip] UiSelector has no direct-child criterion: //android.widget.ListView/android.widget.TextView[1]

Every XPath ends up in one of three groups:

• Exact: the UiSelector finds the same elements in the same order.
• Close: the same first element, but not always the same list, for example //A//B → childSelector. It comes with a warning, and --exact leaves these alone.
• Skip: there is no exact UiSelector. Most skips come with a hint on how to rewrite the locator by hand.

The default is strict: a converted locator finds the same elements as your XPath, so contains(@text,"Total") becomes the case-sensitive textMatches("(?s).*Total.*"). If you prefer simpler, more tolerant locators, --loose writes textContains / textStartsWith (they ignore case) and turns a direct child //A/B into childSelector. Each loose form is marked close with a warning. On the real locators, --loose converts 77 % instead of 73 %.

The bare command only previews. --write saves, --json writes a report with every skip and warning. Node.js 20+, no dependencies. To try a single XPath without installing anything, use the online converter: it runs the same code in the browser.

How I checked it

The order was facts first, the converter last:

1. The source code: the UiAutomator2 server, androidx UiSelector and the XPath engine the driver uses, at pinned versions. That is where the case-insensitive Contains and the \"-only unescaping came from.
2. 170 edge cases (6 of them for --loose), each with a hand-written expected answer, ran on an Android emulator before the converter existed: XPath and UiSelector side by side, comparing the elements they find. Where the device disagreed with me, the case was corrected.
3. 1645 real XPath locators from 20 open-source Appium projects. Every converted one (1169 distinct XPaths) ran on random screens built from its own values and on screens built to break each condition. 0 wrong.
4. Checking the check: 1718 deliberately wrong UiSelectors; the screens caught 99.5 % of them.

Android 16 emulator (and Android 17 for the edge cases), Appium 3.8.0, UiAutomator2 driver 8.7.0, default driver settings. The result: 73 % convert (64 % exact, 9 % close). Most of the rest have no exact UiSelector at all: direct children, absolute /hierarchy/… paths, sibling positions, web and iOS attributes.

Claude 5.5 against the converter

I used the same setup as in the iOS comparison:

• 680 XPaths: 149 edge cases and 531 real locators from 19 projects, shuffled, with neutral ids.
• One request per run: "convert each one to a UiSelector, or skip it with a reason". Claude Code CLI in an empty folder, Read and Write tools only, effort medium, one run per model.
• The judge: every answer that differs from the converter's ran on the emulator next to the XPath.

Scoring: a correct UiSelector earns 1 point, a close one 0.5, a skip 0, and a wrong one −1 (on iOS a wrong chain scored 0): it is worse than a skip, because it looks like a valid locator and finds another element. S is the score on the edge cases, R on the real-world locators, each out of 100 over the locators that have a UiSelector at all: 104 of 149 edge cases and 387 of 531 real ones. The converter scores S 94.2 / R 96.5, not 100, because for some locators it has only a close form, worth half a point. No model beat it on any locator.

Run	Correct	Close	Wrong	Skip	Missed	S	R	Min	Cost
Converter	452	39	0	189	–	94.2	96.5	< 0.1	free
Opus 5.5	400	32	47	179	22	56.7	80.1	12.2	$3.00
Sonnet 5.5	401	32	60	176	11	43.8	80.5	4.9	$0.95
Haiku 5.5	390	32	63	169	26	37.0	78.7	5.2	$0.12

"Missed" means the model skipped a locator that the converter converts correctly. Cost is the API list price the CLI reports.

• On real locators the three models are close to each other (R 79–80), but 16 points below the converter, and each still wrote 31–32 wrong answers there.
• Edge cases tell the models apart: S 37 to 57 against 94.2.
• 7–9 % of all answers were wrong, and they look exactly like the correct ones.
• Opus thought longest and was still wrong 47 times. Most of its 22 missed locators came from assuming that the driver runs XPath 1.0.

What the models get wrong

More than a third of all wrong answers are one pattern: textContains for contains(). Every model wrote it 20–23 times. The next group is a regex without (?s), where . stops at a line break; real resource ids have no line breaks, so those are mostly harmless. Then come the Java-style \\ (Sonnet alone: 15), values that exist only in the page source (an empty text, a toast, a slider's value), and positions inside childSelector.

Mistakes per model

Mistake	Opus	Sonnet	Haiku
Case-insensitive textContains / descriptionContains / textStartsWith	20	23	22
Missing (?s) in a regex	14	8	16
Java-style \\ in a regex or value	1	15	2
Values only the page source has (@text="", a toast, a range widget's value)	0	9	9
Positions: instance() in childSelector, //X[1]	8	0	3
classNameMatches, (?i) for translate(), dropped existence tests, criteria UiSelector does not have	4	5	11
Wrong	47	60	63

Each wrong answer is counted once, under the first mistake it shows.

Is textContains really wrong?

By the definition of this test, yes: contains(@text,"Total") does not find "TOTAL", and textContains("Total") does. The judge screens include such traps on purpose, so every one of the 65 answers found other elements than the XPath there.

In a real app it is less clear. Many people who write contains(@text,"Total") probably never thought about case, and a case-insensitive locator survives a designer switching a label to upper case. The cost is the other side of the same thing: a migration of hundreds of locators quietly makes each one wider. Where a "TOTAL" header sits above the "Total: $5" line, findElement now returns the header. And a check that the label reads "Total" no longer catches a change to "TOTAL".

That is why the converter is strict by default and --loose is a flag you turn on knowingly. In fact, 55 of the 65 answers are character for character what the converter writes with --loose; the other 10 are edge cases where --loose keeps the strict form (substring(), matches(), text(), a value with \). So without rules, Claude converts the way --loose does, only without saying that the locator became wider. If you count textContains as acceptable, the models made at least 27, 37 and 41 wrong answers without rules instead of 47, 60 and 63. Which side are you on? Tell me in the comments.

A prompt with rules

As on iOS, most of these mistakes are about knowing the driver, not about intelligence. So I wrote them down as general rules (about 8,000 characters, rules.md, no answers for particular locators) and ran the three models again:

Run	Correct	Close	Wrong	Skip	Missed	S	R	Min	Cost
Converter	452	39	0	189	–	94.2	96.5	< 0.1	free
Opus 5.5 + rules	448	37	1	189	5	89.4	96.3	5.9	$1.84
Sonnet 5.5 + rules	448	37	1	189	5	89.4	96.3	4.1	$0.89
Haiku 5.5 + rules	443	37	4	189	7	87.5	94.7	6.3	$0.33

• Wrong answers dropped from 47–63 to 1–4, S rose from 37–57 to 88–89 and R from 79–80 to 95–96. The one left for Opus and Sonnet is a line-break case: string-length(@text)=5 → textMatches("(?s).{5}"), where ICU's . takes CR LF as one character. Haiku also dropped the className three times, against an explicit rule.
• Opus got cheaper and faster with the rules: half the time, 60 % of the cost, a quarter of the thinking.
• This is an upper bound. The rules were written from the mistakes on the same 680 locators, and every run was done once.

What the models gave back

The comparison also tested the converter. The first Opus run found one real converter bug: contains(@text,"1.5") was marked exact, but a slider at 1.5 has that text only in the page source, so the XPath finds the slider and the UiSelector does not. It is now a close match with a warning. Across the six runs, the models also found 8 locators the converter skipped although an exact UiSelector exists (normalize-space(), string-length(), translate(), if … then … else, and a few more). I checked each one on the emulator and added all 8 to the converter. After that, no model beats the converter on any locator.

Android is harder than iOS

On iOS, the same three Claude 5.5 models with a plain request made 4–7 wrong class chains out of 676. On Android they made 47–63 out of 680, roughly ten times as many. The gap shows on the real locators too: on iOS the models were within 2 points of the converter (R 94–95 against 96.0), on Android 16 points below it (R 79–80 against 96.5). Part of that is the scoring, since a wrong chain scored 0 on iOS and a wrong UiSelector costs 1 here: at 0, the Android R would be 87–89.

The reason is the target language, not the models. Both converters are strict in the same way: a converted locator must find the same elements as the XPath. On iOS, the obvious answer is usually also the strict one. A class chain filter is an NSPredicate, and its string operators behave like XPath's: CONTAINS and BEGINSWITH are case-sensitive unless you add [c]. So [contains(@label,"Total")] becomes [`label CONTAINS "Total"`], and that is exact.

On Android, the obvious answer is often wider than the XPath. UiSelector has methods with XPath-like names and different behaviour:

• textContains and textStartsWith ignore case. This one trap is 65 of the 170 wrong answers, and it has no iOS counterpart.
• The string literal is not Java: the server unescapes only \", so a Java-style \\ stays two characters.
• instance() inside childSelector counts per container, not across the screen.

A model that "knows" UiSelector from Java code samples has seen these methods used, but rarely with the details that make them differ from XPath. So the case-insensitive, --loose-like answers are an Android problem: on iOS the same habit would produce the exact chain. Even if textContains counts as fine, the Android models made at least 27–41 wrong answers, about four to ten times the iOS count. The iOS mistakes were mostly of other kinds: raw line breaks inside a chain and positions such as [-1].

The two runs are not identical (iOS ran at low and medium effort, Android at medium; the locators are different), so take the ratio as a direction, not a measurement.

The future of UiSelector

Google plans to deprecate and remove UiSelector from UiAutomator, and the UiAutomator2 driver warns that every -android uiautomator locator will then stop working. No date or version is set: UiAutomator 2.4.0 (July 2026) still ships it, and the driver's server bundles 2.3.0. Appium has not announced a replacement yet (appium-uiautomator2-driver#812 is open).

So converting today is a bet that UiSelector stays until Appium moves on; no date is set yet. XPath locators are not affected, and the converter only rewrites strings, so going back is a git revert. The repository has a monthly job that opens an issue when the driver changes a file the conversion rules depend on.

What I would use

The short answer: without rules, no Claude model is safe for a bulk migration; with rules, all three get close to the converter. But the rules are what building and device-checking the converter taught me. Without that work, there would be nothing to put in the prompt.

1. The converter first. It is free, offline, takes under a second for 680 locators, gives the same answer every time and made no wrong UiSelector.
2. A model only for what the converter skips, with the rules in the prompt. With the rules, Sonnet 5.5 at medium scored the same as Opus for half the cost. Most skips have no exact UiSelector at all, so expect an explanation rather than a conversion.
3. Never paste a model's UiSelector into a test without running it on the screen it is meant for. Without the rules, about one in twelve was wrong, and none of them looked wrong.
4. Pick the strictness you want. By default the converter writes exact conversions and close ones with a warning (//A//B → childSelector); --exact writes only the exact ones. --loose adds simpler, case-insensitive forms, also as close with a warning. That is roughly how Claude converts without rules (55 of its 65 textContains answers are the same as --loose), except that the converter tells you the locator became wider.

If you use Claude Code, the repository has a skill that does exactly that: it runs the converter, then reviews each skipped locator and suggests a rewrite, marked as unverified.

Limits

• Emulator only. Android 16 (and 17 for part of the checks), AOSP and Google Play images on an M1 Pro. No real phone, no older Android versions, no OEM builds.
• Default driver settings only. enforceXPath1, allowInvisibleElements and similar settings change the answers.
• Speed was measured on one synthetic View-based app. Compose and WebView screens were not measured.
• One run per model. Two runs with the same rules gave Haiku different mistakes.
• The rules were fitted on the same 680 locators they are scored on.
• Only Claude models. Other LLMs were not tested.

Try it

• Online converter: domovou69.github.io/xpath-to-uiselector
• npx xpath-to-uiselector ./tests (npm, GitHub)
• The full LLM report: audit/llm/report.md
• iOS counterpart: xpath-to-class-chain

Acknowledgements

Thanks to Anthropic: Claude Code helped me build the converter, the checks and the comparison, and the Claude models are also the subject of the test. All numbers come from real runs.

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Mikhail Yesipchuk, SDET/Senior QA Automation Engineer. Have you moved Android locators off XPath, and what broke? Tell me on LinkedIn or open an issue on GitHub.