Bring up keyboard when clicking on EditText

As the title says, I want to bring up the keyboard when I click/tap on the EditText. I've looked at other questions asking for the same thing but the answers just aren't working for me. I don't think the other questions are trying to do this in the onCreate() method and I don't think that they're using this answer for not focusing on the EditText when the app begins. I've added a list of code segments of what I tried and didn't work to avoid redundant answers.

MainActivity.java:

public class MainActivity extends ActionBarActivity {

    private boolean mIsPlaying;
    private int primesLE;
    private GridView mGridView;
    private ImageAdapter mAdapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mIsPlaying = false;

        ViewGroup.LayoutParams layoutParams;

        primesLE = 0;
        int numOfColumns = (int)Math.round(Math.sqrt((double) primesLE));
        int numOfRows = (int)Math.ceil((double)primesLE/(double)numOfColumns);

        View relativeLayout = findViewById(R.id.relativeLayout);
        View title_horizontalScrollView = relativeLayout.findViewById(R.id.title_horizontalScrollView);
        View dataLayout = title_horizontalScrollView.findViewById(R.id.dataLayout);
        mGridView = (GridView) dataLayout.findViewById(R.id.mGridView);
        layoutParams = mGridView.getLayoutParams();
        layoutParams.width = 150*numOfColumns; //this is in pixels
        mGridView.setLayoutParams(layoutParams);
        mGridView.setNumColumns(numOfColumns);
        mAdapter = new ImageAdapter(this, android.R.layout.simple_list_item_1, primesLE);
        mGridView.setAdapter(mAdapter);

        View inputLayout = relativeLayout.findViewById(R.id.inputLayout);
        EditText inputEditText = (EditText)inputLayout.findViewById(R.id.inputEditText);

        //list of what doesn't work

        /*
        inputEditText.setOnFocusChangeListener(new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View v, boolean hasFocus) {
                if (hasFocus) {
                    getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
                }
            }
        });
        */
        /*
        InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.showSoftInput(inputEditText, InputMethodManager.SHOW_IMPLICIT);
        */

        /*
        inputEditText.setFocusableInTouchMode(true);
        inputEditText.setFocusable(true);
        InputMethodManager imm = (InputMethodManager) MainActivity.this.getApplicationContext().getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.hideSoftInputFromWindow(inputEditText.getWindowToken(), 0);
        inputEditText.requestFocus();
        imm.showSoftInput(inputEditText, 0);
        */
        /*        
            inputEditText.setOnKeyListener(new View.OnKeyListener() {

            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
                imm.hideSoftInputFromWindow(
                    inputEditText.getWindowToken(), 0);
                return true;
            }

            });
         */   

    }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    private void playSoE(){

        for(int i = 0; i < primesLE; i++){
            mAdapter.setPositionColor(i, 0xffff0000 + 0x100 * i);
        }
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        Log.d("Menu","Button Pressed");
        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        else if (id == R.id.action_status){
            if(mIsPlaying) {
                mIsPlaying = false;
                item.setIcon(R.drawable.ic_action_play);
                item.setTitle("Play");
                playSoE();
            }
            else {
                mIsPlaying = true;
                item.setIcon(R.drawable.ic_action_pause);
                item.setTitle("Pause");
            }
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/relativeLayout"
    >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:id="@+id/inputLayout"
        android:layout_alignParentTop="true"
        android:background="#a9a9a9"
        >
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:id="@+id/textView"
            android:text="All primes lower this number:"
            />

        <!-- Dummy item to prevent AutoCompleteTextView from receiving focus -->
        <LinearLayout
            android:focusable="true" android:focusableInTouchMode="true"
            android:layout_width="0px" android:layout_height="0px"/>

        <!-- :nextFocusUp and :nextFocusLeft have been set to the id of this component
             to prevent the dummy from receiving focus again -->
        <AutoCompleteTextView android:id="@+id/autotext"
            android:layout_width="fill_parent" android:layout_height="wrap_content"
            android:nextFocusUp="@id/autotext" android:nextFocusLeft="@id/autotext"/>

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:inputType="numberSigned"
            android:ems="10"
            android:id="@+id/inputEditText"
            android:layout_weight="1" />
    </LinearLayout>


    <HorizontalScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/inputLayout"

        android:id="@+id/title_horizontalScrollView"
        android:fillViewport="true">

        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            tools:context=".MainActivity"
            android:id="@+id/dataLayout"
            >

            <GridView
                android:id="@+id/mGridView"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:columnWidth="90dp"
                android:verticalSpacing="10dp"
                android:horizontalSpacing="10dp"
                android:stretchMode="columnWidth"
                android:gravity="center"
                android:layout_alignParentBottom="true" />

        </RelativeLayout>

    </HorizontalScrollView>

</RelativeLayout>

ImageAdapter.java:

public class ImageAdapter extends ArrayAdapter {
    private Context mContext;
    private int mCount;
    private boolean setBlueBackground = false;
    private int[] gridColors;

    public ImageAdapter(Context c, int resource, int count) {
        super(c, resource);
        mContext = c;
        mCount = count;
        gridColors = new int[mCount];
        Arrays.fill(gridColors,Color.LTGRAY);
    }


    public int getCount() {
        return mCount;
    }

    public Object getItem(int position) {
        return null;
    }

    public long getItemId(int position) {
        return 0;
    }

    // create a new ImageView for each item referenced by the Adapter
    public View getView(int position, View convertView, ViewGroup parent) {
        TextView textView;

        if (convertView == null) {
            // if it's not recycled, initialize some attributes
            textView = new TextView(mContext);
            textView.setGravity(Gravity.CENTER);
            textView.setLayoutParams(new GridView.LayoutParams(100, 100));

        } else {
            textView = (TextView) convertView;
        }


        textView.setBackgroundColor(gridColors[position]);

        textView.setText("" + position);
        return textView;
    }

    public void setPositionColor(int position, int color) {
        gridColors[position] = color;
        notifyDataSetChanged();
    }

}

menu_main.xml:

<?xml version="1.0" encoding="utf-8"?>
    <menu xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto">
    <item android:id="@+id/action_status"
        android:icon="@drawable/ic_action_play"
        android:title="Play"
        app:showAsAction="always"/>
    <item android:id="@+id/action_stop"
        android:icon="@drawable/ic_action_stop"
        android:title="Stop"
        app:showAsAction="always"/>
    <item android:id="@+id/action_settings"
            android:title="@string/action_settings"
            app:showAsAction="never"  />

    </menu>

P.S. I'm trying to bring up the keyboard with numbers only, and figure out how how to close it and execute it too.