Android Studio Error “does not support annotation type ...”

Code.

package zaynukov.com.project4; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; public class MainActivity extends AppCompatActivity { public double pervoeChislo (){ EditText chislo1 = (EditText) findViewById(R.id.chislo1); return Double.parseDouble(chislo1.getText().toString()); } public double vtoroeChislo (){ EditText chislo2 = (EditText) findViewById(R.id.chislo2); return Double.parseDouble(chislo2.getText().toString()); } View.OnClickListener OnClick = new View.OnClickListener() { @Override public void onClick(View view) { power power = new power(); TextView resultat = (EditText) findViewById(R.id.resultat); switch (view.getId()){ case R.id.plusButton: resultat.setText(power.resPlus(pervoeChislo(),vtoroeChislo())); break; case R.id.minusButton: resultat.setText(power.resMinus(pervoeChislo(),vtoroeChislo())); break; case R.id.umnButton: resultat.setText(power.resUmn(pervoeChislo(),vtoroeChislo())); break; case R.id.delButton: resultat.setText(power.resDel(pervoeChislo(),vtoroeChislo())); break; case R.id.korenButton: resultat.setText(power.resKoren(pervoeChislo())); break; } } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button plusButton = (Button) findViewById(R.id.plusButton); Button minusButton = (Button) findViewById(R.id.minusButton); Button umnButton = (Button) findViewById(R.id.umnButton); Button delButton = (Button) findViewById(R.id.delButton); Button korenButton = (Button) findViewById(R.id.korenButton); plusButton.setOnClickListener(); umnButton.setOnClickListener(); minusButton.setOnClickListener(); delButton.setOnClickListener(); korenButton.setOnClickListener(); } } 

The build.gradle file contains:

 apply plugin: 'com.android.application' android { compileSdkVersion 25 buildToolsVersion "25.0.0" defaultConfig { applicationId "zaynukov.com.project4" minSdkVersion 15 targetSdkVersion 25 versionCode 1 versionName "1.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } } dependencies { compile fileTree(dir: 'libs', include: ['*.jar']) androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', { exclude group: 'com.android.support', module: 'support-annotations' }) compile 'com.android.support:appcompat-v7:25.0.0' testCompile 'junit:junit:4.12' } 

Android Studio gives errors:

Error: (57, 6) error-type annotations are not supported in -source 1.7 (use -source 8 or higher to enable type annotations)

Error: (51, 5) error: illegal start of expression

Error: (51, 14) error: ';' expected

Error: Execution failed for task ': app: compileDebugJavaWithJavac'. Compilation failed; see the compiler error output for details.