安卓网络连接Retrofit和使用ViewModel

Step 1: Add Retrofit dependencies to Gradle

Open build.gradle (Module: app).
In the dependencies section, add these lines for the Retrofit libraries:

implementation "com.squareup.retrofit2:retrofit:$version_retrofit"
implementation "com.squareup.retrofit2:converter-scalars:$version_retrofit"

version_retrofit = "2.9.0"(project-level)

Step 2: Add support for Java 8 language features

Many third party libraries including Retrofit2 use Java 8 language features. The Android Gradle plugin provides built-in support for using certain Java 8 language features. To use these built-in features, update the module’s build.gradle file, as shown below:

android {
  ...

  compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }
  
  kotlinOptions {
    jvmTarget = JavaVersion.VERSION_1_8.toString()
  }
}

use ViewModel->LiveData

//ViewModel
implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0'