Is there a way to go back to Java 7?

Is there a way to go back to Java 7?

Currently, Android applications are programmed by using Android Studio and usually use Java 7.

If you import the library symja-java8, you will get a compilation error like this

Error: Error converting bytecode to dex:
Cause: Dex can not parse version 52 byte code.
This is caused by library dependencies that have been compiled using Java 8 or above.
If you are using the 'java' gradle plugin in a library submodule add
targetCompatibility = '1.7'
sourceCompatibility = '1.7'
to that submodule's build.gradle file.

I added those two lines to build.gradle but did not work.

I have tried to fix for a long time but there is no way to compile this library.

Who has compiled symja-java8 library on Android Studio?

I also enable jack. But this only support Android N a above.

Error:Default method org.hipparchus.analysis.solvers.BracketedRealFieldUnivariateSolver$Interval solveInterval(int null, org.hipparchus.analysis.RealFieldUnivariateFunction null, org.hipparchus.RealFieldElement null, org.hipparchus.RealFieldElement null) not supported in Android API level less than 24
Error:Default method org.hipparchus.analysis.solvers.BracketedUnivariateSolver$Interval solveInterval(int null, org.hipparchus.analysis.UnivariateFunction null, double null, double null) not supported in Android API level less than 24
Error:Default method boolean isTransposable() not supported in Android API level less than 24
Error:Default method org.hipparchus.linear.RealVector operateTranspose(org.hipparchus.linear.RealVector null) not supported in Android API level less than 24
Error:Execution failed for task ':app:transformClassesWithPreJackPackagedLibrariesForDebug'.
        > com.android.build.api.transform.TransformException: com.android.builder.core.JackToolchain$ToolchainException: Jack compilation exception

If possible, please move on to Java 7, the Java version 7 works very stable.

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