Cannot use lambda functions in Android with Java 1.8

Question

The library I'm using is bychan, I can't even include it in a Nougat empty app project either loaded as module or through jar.

So this is an example of what was returned in Android Studio's messages:

Can someone explain what they mean by "unknown interface" in the errors below?

Error:TokenDefinitionBuilder.java:118-119: Lambda coming from jar file need their interfaces on the classpath to be compiled, unknown interfaces are java.util.function.Function
Error:TokenDefinitionBuilder.java:118-119: Lambda coming from jar file need their interfaces on the classpath to be compiled, unknown interfaces are java.util.function.Predicate
...
Error:com.android.jack.JackAbortException

This came from a library I've used. I thought adding the types in angle brackets would help? I don't know if it did anything though.

This is the line 118-119 in that library:

strings.stream().<StringMatcher>map(StringMatcher::new).map(
    m -> m.tryMatch(input, searchStart)).filter(Objects::nonNull).findFirst().orElse(null));

I'm not sure what it is complaining about? What should I do or change to evade this problem? I had thought that maybe Android doesn't support Lambda Expressions, but the error clearly stated "Lambda coming from...", which means it recognized I used a lambda expression.

Please help.

---

Update

I have included the library by compiling it in a jar inside another jar library, if that helps. I'm new to the world of Android if you can't tell.

Updates 2

I don't think this is related to the API version? I've set my build target to 25. But the build is still failing.

Also, if you look below, I don't see an option for 1.8? But I've set the build JDK to my 1.8 JDK location.

---

Gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.0"
    defaultConfig {
        applicationId "this.is.where.i.have.my.id"
        minSdkVersion 25
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        jackOptions {
            enabled true
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.0.1'
    compile 'com.android.support:support-v4:25.0.0'
    compile 'com.android.support:design:25.0.0'
    compile 'com.android.support:preference-v7:25.0.0'
    compile 'com.android.support:preference-v14:25.0.0'
    compile 'com.google.android.gms:play-services-appindexing:9.8.0'
    testCompile 'junit:junit:4.12'
    compile 'com.google.code.gson:gson:2.8.0'
    compile files('libs/my_lib_that_contains_lambda.jar')
}

Answer 1

I would not suggest to use java 8. It is not supported nowadays. But, even, it will: remember, that each devices has got its own java machine that will not update. I mean, if you wanna be sure your app works properly setup your project as java 6. Old devices this never support up-to-date JMV

Read this discussion too

Which JDK version (Language Level) is required for Android Studio?