2020-12-28 16:12:27.797 16794-16794/com.yucha.retrofit W/.yucha.retrofi: Accessing hidden method Lcom/android/org/conscrypt/OpenSSLSocketImpl;->setUseSessionTickets(Z)V (greylist-max-q,core-platform-api, reflection, denied)
2020-12-28 16:12:27.798 16794-16794/com.yucha.retrofit D/AndroidRuntime: Shutting down VM
    
    
    --------- beginning of crash
2020-12-28 16:12:27.802 16794-16794/com.yucha.retrofit E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.yucha.retrofit, PID: 16794
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:414)
        at android.view.View.performClick(View.java:7448)
        at android.view.View.performClickInternal(View.java:7425)
        at android.view.View.access$3600(View.java:810)
        at android.view.View$PerformClick.run(View.java:28305)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409)
        at android.view.View.performClick(View.java:7448) 
        at android.view.View.performClickInternal(View.java:7425) 
        at android.view.View.access$3600(View.java:810) 
        at android.view.View$PerformClick.run(View.java:28305) 
        at android.os.Handler.handleCallback(Handler.java:938) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:223) 
        at android.app.ActivityThread.main(ActivityThread.java:7656) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) 
     Caused by: java.lang.ExceptionInInitializerError
        at okhttp3.internal.platform.Platform.get(Platform.java:85)
        at okhttp3.OkHttpClient.newSslSocketFactory(OkHttpClient.java:263)
        at okhttp3.OkHttpClient.<init>(OkHttpClient.java:229)
        at okhttp3.OkHttpClient.<init>(OkHttpClient.java:202)
        at retrofit2.Retrofit$Builder.build(Retrofit.java:614)
        at com.yucha.retrofit.MainActivity.getRequest(MainActivity.java:31)
        at java.lang.reflect.Method.invoke(Native Method) 
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409) 
        at android.view.View.performClick(View.java:7448) 
        at android.view.View.performClickInternal(View.java:7425) 
        at android.view.View.access$3600(View.java:810) 
        at android.view.View$PerformClick.run(View.java:28305) 
        at android.os.Handler.handleCallback(Handler.java:938) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:223) 
        at android.app.ActivityThread.main(ActivityThread.java:7656) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) 
     Caused by: java.lang.IllegalStateException: Expected Android API level 21+ but was 30
        at okhttp3.internal.platform.AndroidPlatform.buildIfSupported(AndroidPlatform.java:238)
        at okhttp3.internal.platform.Platform.findPlatform(Platform.java:202)
        at okhttp3.internal.platform.Platform.<clinit>(Platform.java:79)
        at okhttp3.internal.platform.Platform.get(Platform.java:85) 
        at okhttp3.OkHttpClient.newSslSocketFactory(OkHttpClient.java:263) 
        at okhttp3.OkHttpClient.<init>(OkHttpClient.java:229) 
        at okhttp3.OkHttpClient.<init>(OkHttpClient.java:202) 
        at retrofit2.Retrofit$Builder.build(Retrofit.java:614) 
        at com.yucha.retrofit.MainActivity.getRequest(MainActivity.java:31) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409) 
        at android.view.View.performClick(View.java:7448) 
        at android.view.View.performClickInternal(View.java:7425) 
        at android.view.View.access$3600(View.java:810) 
        at android.view.View$PerformClick.run(View.java:28305) 
        at android.os.Handler.handleCallback(Handler.java:938) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:223) 
        at android.app.ActivityThread.main(ActivityThread.java:7656) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) 
2020-12-28 16:12:27.888 16794-16794/? I/Process: Sending signal. PID: 16794 SIG: 9

gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.yucha.retrofit"
        minSdkVersion 29
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

dependencies {
    implementation fileTree(dir: "libs", include: ["*.jar"])
    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
    implementation 'com.squareup.retrofit2:retrofit:2.7.1'
    

}

@拉大锯