button.xml

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">


    <Button xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/hashtagbutton"
        android:textColor="#000000"
        android:textSize="12sp"
        android:text="xxx"
        android:background="@drawable/buttonshape"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
</LinearLayout>

buttonshape.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
    <corners
        android:radius="5dp"
        />
    <solid
        android:color="#ffffff"
        />
    <padding
        android:left="0dp"
        android:top="0dp"
        android:right="0dp"
        android:bottom="0dp"
        />
    <size
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
    <stroke
        android:width="1dp"
        android:color="#cccccc"
        />
</shape>

main.java



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

        String[] Hashtags = new String[]{"a", "b", "c", "d"};

        createButtons(Hashtags);

    }

    private void createButtons(String[] Hashtags) {

        ArrayList<Button> buttons = new ArrayList<Button>();
        RelativeLayout bg = (RelativeLayout) findViewById(R.id.Hashtags);

        View view = (View)LayoutInflater.from(this).inflate(R.layout.button, null);
        Button buttonByXml = (Button) view.findViewById(R.id.hashtagbutton);

        Integer i = 0;
        for(String Hashtag : Hashtags){

            Button newButton = new Button(this);
            newButton.setId(i + 1);
            newButton.setText("#" + Hashtag);
            newButton.setLayoutParams(new LayoutParams(buttonByXml.getLayoutParams()));

            buttons.add(newButton);

            RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);


            if(i > 0) {
                int id = buttons.get(i - 1).getId();
                lp.addRule(RelativeLayout.RIGHT_OF, id);
            }
            i++;

            bg.addView(newButton,lp);
        }

    }