Geocoding is the process of finding the geographical coordinates of the given location, So if you looking help to create Geo Location function see code example below. Here I have created edit text using place name for users. When User enters any place like country, city etc user will get that particular location latitude along with in below example I have used GoogleMapsActivity. Below code will clearly described you how to create Geo Location coding in android.

Step(1)MainActivity

public class MainActivity extends Activity {

    double latitude, longitude;
    EditText locationName;
    Button okbtn;
    TextView result;

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

        locationName = (EditText) findViewById(R.id.location);
        okbtn = (Button) findViewById(R.id.button1);
        result = (TextView) findViewById(R.id.textView1);
        okbtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                Geocoder geocoder = new Geocoder(getBaseContext(), Locale
                        .getDefault());

                try {
                    List<Address> address;

                    address = geocoder.getFromLocationName(locationName
                            .getText().toString(), 1);
                    if (address.size() > 0) {
                        latitude = address.get(0).getLatitude();
                        longitude = address.get(0).getLongitude();
                    }

                } catch (IOException e) {
                    e.printStackTrace();
                } finally {

                }

                result.setText("" + latitude + "\n" + longitude);

            }
        });
    }

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

}

Step(2)-main.xml layout-

<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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />



    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView1"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="86dp"
        android:text="OK" />

    <EditText
        android:id="@+id/location"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/button1"
        android:layout_below="@+id/textView1"
        android:layout_marginTop="22dp"
        android:ems="10" >

        <requestFocus />
    </EditText>

</RelativeLayout>