ActivityMain.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:gravity="center"
        android:layout_marginBottom="10dp">

        <EditText
            android:id="@+id/noqr"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:ems="10"
            android:imeOptions="actionDone"
            android:singleLine="true"
            android:hint="Input Nomor Barcode" />

        <Button
            android:id="@+id/cekqr"
            android:layout_width="80dp"
            android:layout_height="35dp"
            android:layout_marginLeft="20dp"
            android:background="@color/colorAccent"
            android:text="CEK" />

    </LinearLayout>

    <Button
        android:id="@+id/scanqrbt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="SCAN QR CODE" />

    <WebView
        android:id="@+id/webhasil"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>