Java Question lambda expressions are not supported in -source 7

lambda expressions are not supported in -source 7
        runOnUiThread(() -> {
                         ^
  (use -source 8 or higher to enable lambda expressions)
1 error

javac 11.0.1

Error.

    private void showHintDialog() {
        runOnUiThread(() -> {

        });
    }

Completed successfully.
Starting step: Creating jar file.
Completed successfully.
Starting step: Creating XML file.
javadoc: warning - The old Doclet and Taglet APIs in the packages
com.sun.javadoc, com.sun.tools.doclets and their implementations
are planned to be removed in a future JDK release. These
components have been superseded by the new APIs in jdk.javadoc.doclet.
Users are strongly recommended to migrate to the new APIs.
C:\Users\johans\Documents\Basic4Android\b4aProjects\JamesNFC\Nfcregtest\app\src\com\reginald\nfcregtest\CheckCardCallbackV2Wrapper.java:3: error: package android.os does not exist
import android.os.Bundle;
                 ^
C:\Users\johans\Documents\Basic4Android\b4aProjects\JamesNFC\Nfcregtest\app\src\com\reginald\nfcregtest\CheckCardCallbackV2Wrapper.java:4: error: package android.os does not exist
import android.os.RemoteException;
                 ^
C:\Users\johans\Documents\Basic4Android\b4aProjects\JamesNFC\Nfcregtest\app\src\com\reginald\nfcregtest\CheckCardCallbackV2Wrapper.java:5: error: package android.util does not exist
import android.util.Log;
                   ^
C:\Users\johans\Documents\Basic4Android\b4aProjects\JamesNFC\Nfcregtest\app\src\com\reginald\nfcregtest\CheckCardCallbackV2Wrapper.java:10: error: cannot access IInterface
public class CheckCardCallbackV2Wrapper extends CheckCardCallbackV2.Stub {
       ^
  class file for android.os.IInterface not found
java.lang.NullPointerException
    at jdk.compiler/com.sun.tools.javac.comp.TypeEnter$MembersPhase.runPhase(TypeEnter.java:934)
    at jdk.compiler/com.sun.tools.javac.comp.TypeEnter$Phase.doCompleteEnvs(TypeEnter.java:282)
    at jdk.compiler/com.sun.tools.javac.comp.TypeEnter$MembersPhase.doCompleteEnvs(TypeEnter.java:877)
    at jdk.compiler/com.sun.tools.javac.comp.TypeEnter$Phase.completeEnvs(TypeEnter.java:251)
    at jdk.compiler/com.sun.tools.javac.comp.TypeEnter$Phase.completeEnvs(TypeEnter.java:266)
    at jdk.compiler/com.sun.tools.javac.comp.TypeEnter$Phase.completeEnvs(TypeEnter.java:266)
    at jdk.compiler/com.sun.tools.javac.comp.TypeEnter$Phase.completeEnvs(TypeEnter.java:266)
    at jdk.compiler/com.sun.tools.javac.comp.TypeEnter.complete(TypeEnter.java:198)
    at jdk.compiler/com.sun.tools.javac.code.Symbol.complete(Symbol.java:642)
    at jdk.compiler/com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:1326)
    at jdk.compiler/com.sun.tools.javac.comp.Enter.complete(Enter.java:583)
    at jdk.compiler/com.sun.tools.javac.comp.Enter.main(Enter.java:560)
    at jdk.javadoc/com.sun.tools.javadoc.main.JavadocEnter.main(JavadocEnter.java:81)
    at jdk.javadoc/com.sun.tools.javadoc.main.JavadocTool.getRootDocImpl(JavadocTool.java:222)
    at jdk.javadoc/com.sun.tools.javadoc.main.Start.parseAndExecute(Start.java:426)
    at jdk.javadoc/com.sun.tools.javadoc.main.Start.begin(Start.java:238)
    at jdk.javadoc/com.sun.tools.javadoc.main.Start.begin(Start.java:224)
    at jdk.javadoc/com.sun.tools.javadoc.Main.execute(Main.java:174)
    at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:419)
    at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:344)
    at jdk.javadoc/jdk.javadoc.internal.tool.Main.execute(Main.java:63)
    at jdk.javadoc/jdk.javadoc.internal.tool.Main.main(Main.java:52)
javadoc: error - fatal exception

Error.