• Codecademy: https://www.codecademy.com/learn/learn-java

 

• Coding Bat is a website filled with amazing practice problems which give responsive feedback. It also has a large amount of reading to help further your java knowledge: https://codingbat.com/java

 

• FreeCodeCamp: https://www.youtube.com/results?search_query=freecodecamp+intermediate+java

 

• ​​FreeCodeCamp: https://www.youtube.com/results?search_query=freecodecamp+advanced+java

 

• Free Java textbook used for competitions: http://www.bluepelicanjava.co

 

• Free youtube playlist from an APCS teacher with his entire course: https://www.youtube.com/playlist?list=PL64DA018268EC0E2C

 

• ​GeeksforGeeks: https://www.geeksforgeeks.org/arrays-tostring-in-java-with-examples/​

 

• Oracle (Official Java Tutorial): https://docs.oracle.com/javase/tutorial/java/index.html

 

• Programiz: https://www.programiz.com/java-programming/packages-import

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• The Java API (There are over two dozen other methods for an Array List): https://docs.oracle.com/javase/8/docs/api/java/util/ArrayList.html

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• The Java API is a large database with info about all the default Java classes. It features info on all the familiar data types and methods which can be used with them: https://docs.oracle.com/javase/7/docs/api/

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• Tutorialspoint: https://www.tutorialspoint.com/java/java_overview.htm

 

• ​w3schools.com: https://www.w3schools.com/java/

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• Repl.it (Code, create, and learn together-compiler): https://repl.it/