title: Failed to resolve: com.android.support:appcompat-v7:27.+ (Dependency Error)
body: <p>I am having this issue in Android studio.</p>
  
  <pre><code>Error:Failed to resolve: com.android.support:appcompat-v7:27.+
  &lt;a href="install.m2.repo"&gt;Install Repository and sync project&lt;/a&gt;&lt;br&gt;&lt;a href="open.dependency.in.project.structure"&gt;Show in Project Structure 
  dialog&lt;/a&gt;
  </code></pre>
  
  <p>My Android Studio is full of error android studio cannot identify libraries. The whole screen looks like this.</p>
  
  <p><img src="https://i.stack.imgur.com/lzuZo.png" alt="image"></p>
  
  <p>This is my <code>Gradle</code> code:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 27
      buildToolsVersion "27.0.1"
  
      defaultConfig {
          applicationId "com.example.hp.temp"
          minSdkVersion 21
          targetSdkVersion 27
          versionCode 1
          versionName "1.0"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      testCompile 'junit:junit:4.12'
      compile 'com.android.support:appcompat-v7:27.+'
  }
  </code></pre>