Comparison

統計DS発展対策 vs Java SE 21 Developer

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

統計DS発展対策

Features
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統計DS発展 全500問に対応した問題集アプリ。章別演習・ランダム出題・模擬試験など複数モードで効率的に学習できます。

About

Java SE 21 Developer

Features
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Keep studying across your phone, tablet and desktop. Use your phone on the move and a tablet or desktop when you want more room to study. Connect the same StudyCert account to continue your learning in the app and on the desktop web. Prepare for Oracle Java SE 21 / 1Z0-830 with 500 practice questions and 149 key terms. Study coverage · 10 areas • Handling Date, Time, Text, Numeric and Boolean Values • Controlling Program Flow • Using Object-Oriented Concepts in Java • Handling Exceptions • Working with Arrays and Collections • Working with Streams and Lambda expressions • Packaging and Deploying Java Code • Managing Concurrent Code Execution • Using Java I/O API • Implementing Localization 1. Build your foundation with key terms Use flashcards to learn meanings, exam context and selection cues. Mark terms as known or not yet known, then revisit unstudied or unfamiliar cards. Edit card content to suit your learning and restore the original when needed. 2. Practice and understand each answer Study in 50-question sets, by domain or by difficulty. Work through single- and multiple-choice questions, then read the explanation for the answer and each option. Choose all, unfinished or wrong questions; shuffle questions and choices; use a study timer; and resume where you left off. From the results of domain study, continue with key terms and related questions in the next domain. 3. Review mistakes and uncertain concepts Choose recent errors, review marks or repeated mistakes on the Review screen and practice them again. Check accuracy by domain alongside the terms you know or still need to learn. The glossary report shows term-learning status and accuracy on related questions together. 4. Check your preparation with a mock exam Practice time management with 50 questions in 120 minutes. Change answers before submission, resume a saved exam and receive grading when time expires. Afterwards, see correct, wrong and unanswered counts, your score and domain results, then revisit mistakes. This practice feature uses the included questions and does not determine an official exam score or pass result. Tools that fit your study routine Optional audio study reads terms and meanings aloud. Choose whether to include exam context and selection cues, set repeats and pauses, and control playback with the mini player. In the mobile app, audio can continue in the background and with the screen locked. A study calendar, learning streaks, weekly goals, reminders for unmet goals and light, dark or system themes support your routine. Learning records are managed for each supported language. Some features require paid access. Check the included features and price on the purchase screen. Purchase restoration is supported. This is an independent study aid, not an official, affiliated or endorsed app of any exam administrator or certification body. Exam names and trademarks belong to their respective owners.

Screenshots

統計DS発展対策4 screens
Java SE 21 Developer4 screens

Verdict

The call

The clearest difference is price: Java SE 21 Developer at Free against 統計DS発展対策's $4.99. 統計DS発展対策's advantage is in-app purchases (none vs 1) and update cadence (every 3 days vs weekly). On ads, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Java SE 21 Developer is free to download; 統計DS発展対策 costs $4.99 up front. Java SE 21 Developer sells 1 one-off in-app purchase. 統計DS発展対策 asks for nothing beyond the download.

UpkeepUpdate frequency

統計DS発展対策 ships an update every 3 days, Java SE 21 Developer weekly. Both last shipped on November 13, 2026.

Scorecard3 real differences · 3 level
統計DS発展対策 versus Java SE 21 Developer: the parameters behind the verdict, then further details
Parameter統計DS発展対策Java SE 21 Developer
Price$4.99Free — better
Update frequencyEvery 3 days — betterWeekly
AdsNoNo
In-app purchasesNo — betterYes
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.115.1
Further details — not scored
Size34 MB233 MB
Age rating4+4+
Developersatoshi yoshidaCHOI SEONGMIN

In-app purchases

None

統計DS発展対策

No in-app purchases

1 purchases

Java SE 21 Developer

One-time1
  • Lifetime Access$4.99

Questions

Is 統計DS発展対策 free?
統計DS発展対策 costs $4.99, with no in-app purchases.
Is Java SE 21 Developer free?
Java SE 21 Developer is free to download, with in-app purchases available.
Do 統計DS発展対策 or Java SE 21 Developer have ads?
Neither 統計DS発展対策 nor Java SE 21 Developer shows ads.
Which is updated more often, 統計DS発展対策 or Java SE 21 Developer?
統計DS発展対策 ships an update every 3 days, and Java SE 21 Developer weekly. Most recently, 統計DS発展対策 was updated on November 13, 2026 and Java SE 21 Developer on November 13, 2026.

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