I want to translate english text to hindi using followong API : **Following is my TextActivity**
    package com.ds.texar;
    
    import android.app.Activity;
    import android.content.ClipData;
    import android.content.ClipboardManager;
    import android.content.Context;
    import android.os.Bundle;
    import android.speech.tts.TextToSpeech;
    import android.support.design.widget.FloatingActionButton;
    import android.support.v7.app.AppCompatActivity;
    import android.support.v7.widget.Toolbar;
    import android.view.View;
    import android.widget.TextView;
    import android.widget.Toast;
    import android.widget.ToggleButton;
    import com.google.api.translate.Language;
    import com.google.api.translate.Translate;
    
    import java.util.Locale;
    import java.util.concurrent.ExecutionException;
    
    public class TextActivity extends AppCompatActivity {
    
        Context context;
        TextToSpeech textToSpeech;
        private String textFromMain = "";
        ToggleButton languageToggleButton;
        private String outputHindiString = "";
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_text);
            Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
            setSupportActionBar(toolbar);
    
            //setting text string received from main activity
            final TextView textView = (TextView)findViewById(R.id.mtextview);
            textFromMain = getIntent().getStringExtra("mytext");
            textView.setText(textFromMain);
            context = getApplicationContext();
    
            textToSpeech = new TextToSpeech(getApplicationContext(), new TextToSpeech.OnInitListener(){
                @Override
                public void onInit(int status) {
                    if(status != TextToSpeech.ERROR) {
                        textToSpeech.setLanguage(Locale.UK);
                    }
                }
            });
    
            languageToggleButton = (ToggleButton) findViewById(R.id.language_toggle_button);
            languageToggleButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if(languageToggleButton.isChecked()){
                            try {
                                Translate.setHttpReferrer("http://android-er.blogspot.com/");
                                outputHindiString = Translate.execute(textFromMain,
                                        Language.ENGLISH, Language.HINDI);
                            } catch (Exception ex) {
                                ex.printStackTrace();
                                outputHindiString = "Error";
                            }
                            textView.setText(outputHindiString);
                    }
                    else{
                        textView.setText(textFromMain);
                    }
                }
            });
    
            FloatingActionButton copyText = (FloatingActionButton) findViewById(R.id.copy_text);
            copyText.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
    //                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
    //                        .setAction("Action", null).show();
                    ClipboardManager clipboard = (ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE);
                    ClipData clip = ClipData.newPlainText("myText", textFromMain);
                    clipboard.setPrimaryClip(clip);
                    Toast.makeText(context, "Your text copied.", Toast.LENGTH_SHORT).show();
    //                toast.setGravity(Gravity.TOP| Gravity.LEFT, 10, 300);
    //                toast.show();
                }
            });
    
            final FloatingActionButton textToSpeechButton = (FloatingActionButton) findViewById(R.id.text_to_speech);
            textToSpeechButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
    //                Toast.makeText(getApplicationContext(), textFromMain, Toast.LENGTH_SHORT).show();
                    textToSpeech.speak(textFromMain, TextToSpeech.QUEUE_FLUSH, null, null);
                }
            });
        }
    
        @Override
        public void onPause(){
            if(textToSpeech !=null){
                textToSpeech.stop();
                textToSpeech.shutdown();
            }
            super.onPause();
        }
    }
    
Here is Layout xml file

    <?xml version="1.0" encoding="utf-8"?>
    <android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        tools:context="com.ds.texar.TextActivity">
    
        <android.support.design.widget.AppBarLayout
            android:id="@+id/app_bar"
            android:layout_width="match_parent"
            android:layout_height="@dimen/app_bar_height"
            android:fitsSystemWindows="true"
            android:theme="@style/AppTheme.AppBarOverlay">
    
            <android.support.design.widget.CollapsingToolbarLayout
                android:id="@+id/toolbar_layout"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:fitsSystemWindows="true"
                app:contentScrim="?attr/colorPrimary"
                app:layout_scrollFlags="scroll|exitUntilCollapsed">
    
                <android.support.v7.widget.Toolbar
                    android:id="@+id/toolbar"
                    android:layout_width="match_parent"
                    android:layout_height="?attr/actionBarSize"
                    app:layout_collapseMode="pin"
                    app:popupTheme="@style/AppTheme.PopupOverlay" />
    
            </android.support.design.widget.CollapsingToolbarLayout>
        </android.support.design.widget.AppBarLayout>
    
        <include
            android:id="@+id/include2"
            layout="@layout/content_text" />
    
        <android.support.design.widget.FloatingActionButton
            android:id="@+id/text_to_speech"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/fab_margin"
            app:layout_anchor="@id/app_bar"
            app:layout_anchorGravity="bottom|end"
            app:srcCompat="@android:drawable/ic_lock_silent_mode_off" />
    
        <android.support.design.widget.FloatingActionButton
            android:id="@+id/copy_text"
            android:layout_width="51dp"
            android:layout_height="55dp"
            android:layout_gravity="top|left"
            android:layout_margin="16dp"
            android:clickable="true"
            app:fabSize="mini"
            app:layout_anchor="@+id/include2"
            app:layout_anchorGravity="bottom|right"
            app:srcCompat="?attr/actionModeCopyDrawable" />
    
        <ToggleButton
            android:id="@+id/language_toggle_button"
            android:layout_width="65dp"
            android:layout_height="wrap_content"
            android:layout_gravity="top|center_horizontal"
            android:layout_margin="16dp"
            android:background="@drawable/check"
            android:textOff=""
            android:textOn=""
            android:focusable="false"
            android:focusableInTouchMode="false"
            app:layout_anchor="@+id/include2"
            app:layout_anchorGravity="bottom|center_horizontal" />
    
    
    </android.support.design.widget.CoordinatorLayout>
Here is AndroidManifest.xml

    <?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
        package="com.ds.texar">
    
        <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
        <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
        <uses-permission android:name="android.permission.CAMERA" />
        <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    
        <uses-feature
            android:name="android.hardware.camera"
            android:required="true" />
        <uses-feature android:name="android.hardware.camera.autofocus" />
        <uses-feature android:name="android.hardware.sensor.accelerometer" />
        <uses-feature android:name="android.hardware.sensor.light" />
    
        <meta-data
            android:name="com.google.android.gms.vision.DEPENDENCIES"
            android:value="ocr" />
    
        <application
            android:allowBackup="true"
            android:icon="@mipmap/ic_launcher"
            android:label="@string/app_name"
            android:roundIcon="@mipmap/ic_launcher_round"
            android:supportsRtl="true"
            android:theme="@style/AppTheme">
            <activity
                android:name=".MainActivity"
                android:label="@string/app_name"
                android:theme="@style/AppTheme.NoActionBar">
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
    
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>
            <activity
                android:name=".TextActivity"
                android:label="@string/title_activity_text"
                android:theme="@style/AppTheme.NoActionBar"></activity>
        </application>
    
    </manifest>
Error log:

> Information:Gradle tasks [:app:generateDebugSources,
> :app:mockableAndroidJar, :app:prepareDebugUnitTestDependencies,
> :app:generateDebugAndroidTestSources, :app:compileDebugSources,
> :app:compileDebugUnitTestSources, :app:compileDebugAndroidTestSources]
> C:\Users\DELL_PC\Desktop\Texar\app\src\main\java\com\ds\texar\TextActivity.java
> Error:(16, 32) error: package com.google.api.translate does not exist
> Error:(17, 32) error: package com.google.api.translate does not exist
> Error:(58, 29) error: cannot find symbol variable Translate Error:(60,
> 37) error: cannot find symbol variable Language Error:(60, 55) error:
> cannot find symbol variable Language Error:(59, 49) error: cannot find
> symbol variable Translate Error:Execution failed for task
> ':app:compileDebugJavaWithJavac'.
> > Compilation failed; see the compiler error output for details. Information:BUILD FAILED Information:Total time: 6.836 secs
> Information:7 errors Information:0 warnings Information:See complete
> output in console

