Should I buy books on Android 2 and Java 7 if Android 5 and Java 8 are now?

Question

Java

Hello, I was looking for books on development for Android and Java, all new books are either expensive or in the original in English.
Then I found used books on Android 2 and Java 7.
The price of a book on Android is very, very low, only $ 1.
For Java, $ 5
But I’m thinking of buying them and learning, or are they no longer relevant today?
I don't want to pay twice and keep them in my collection.

Answer 1

Java 7 is very relevant. Enterprise solutions are never in a hurry to upgrade to newer versions, so you don’t have to worry about this, but Android 2 is clearly outdated

Answer 2

If you need Java for Android development, then you don't need Java 8. Only Android started supporting Java 7. Java 8 on Android will come in a couple of years, not earlier.