Convert String to Uppercase & Lowercase using Java Stream API | Java Coding Interview Question

Published: 07 April 2026
on channel: codemonarch

🔥 In this video we solve a clean and practical Java coding
problem — Convert a String to Uppercase and Lowercase using
Java Stream API! Simple, modern and beginner friendly Java
8 solution explained step by step!

✅ Problem statement explained clearly
✅ Using map() with toUpperCase() in Stream API
✅ Using map() with toLowerCase() in Stream API
✅ Convert each character individually using chars()
✅ Using Collectors.joining() to rebuild the string
✅ Convert alternate characters upper and lowercase
✅ Multiple clean Java 8 approaches compared
✅ Time and space complexity analysis

💡 String case conversion using Stream API is a very common
warm-up question in Java interviews! It perfectly tests your
understanding of map(), chars(), Collectors.joining() and
method references — all core Java 8 Stream concepts!

🎯 Perfect for:
👉 Java developers preparing for coding interviews
👉 Java 8 Stream API learners
👉 Students practicing String problems in Java
👉 Anyone who wants clean functional Java solutions

👍 If this video helped you please LIKE, SHARE & SUBSCRIBE
for more Java Stream API coding problems. Drop your solution
or questions in the COMMENTS — we read every single one!

#Java #StreamAPI #JavaInterview #JavaCodingInterview #Java8
#JavaStreams #CodingInterview #JavaString #LearnJava
#JavaDeveloper

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