how to make a walker to this (in bootstrap, i try but not work)

I use this navwalker

<?php
class wp_bootstrap_navwalker extends Walker_Nav_Menu {

    public function start_lvl( &$output, $depth = 0, $args = array() ) {
    $indent = str_repeat( "\t", $depth );
    $output .= "\n$indent<ul role=\"menu\" class=\" dropdown-menu\">\n";
}


public function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
    $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';

    if ( strcasecmp( $item->attr_title, 'divider' ) == 0 && $depth === 1 ) {
        $output .= $indent . '<li role="presentation" class="divider">';
    } else if ( strcasecmp( $item->title, 'divider') == 0 && $depth === 1 ) {
        $output .= $indent . '<li role="presentation" class="divider">';
    } else if ( strcasecmp( $item->attr_title, 'dropdown-header') == 0 && $depth === 1 ) {
        $output .= $indent . '<li role="presentation" class="dropdown-header">' . esc_attr( $item->title );
    } else if ( strcasecmp($item->attr_title, 'disabled' ) == 0 ) {
        $output .= $indent . '<li role="presentation" class="disabled"><a href="#">' . esc_attr( $item->title ) . '</a>';
    } else {

        $class_names = $value="";

        $classes = empty( $item->classes ) ? array() : (array) $item->classes;
        $classes[] = 'menu-item-' . $item->ID;

        $class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args ) );

        if ( $args->has_children )
            $class_names .= ' dropdown';

        if ( in_array( 'current-menu-item', $classes ) )
            $class_names .= ' active';

        $class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';

        $id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args );
        $id = $id ? ' id="' . esc_attr( $id ) . '"' : '';

        $output .= $indent . '<li' . $id . $value . $class_names .'>';

        $atts = array();
        $atts['title']  = ! empty( $item->title )   ? $item->title  : '';
        $atts['target'] = ! empty( $item->target )  ? $item->target : '';
        $atts['rel']    = ! empty( $item->xfn )     ? $item->xfn    : '';

        // If item has_children add atts to a.
        if ( $args->has_children && $depth === 0 ) {
            $atts['href']           = '#';
            $atts['data-toggle']    = 'dropdown';
            $atts['class']          = 'dropdown-toggle';
            $atts['aria-haspopup']  = 'true';
        } else {
            $atts['href'] = ! empty( $item->url ) ? $item->url : '';
        }

        $atts = apply_filters( 'nav_menu_link_attributes', $atts, $item, $args );

        $attributes="";
        foreach ( $atts as $attr => $value ) {
            if ( ! empty( $value ) ) {
                $value = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );
                $attributes .= ' ' . $attr . '="' . $value . '"';
            }
        }

        $item_output = $args->before;


        if ( ! empty( $item->attr_title ) )
            $item_output .= '<a'. $attributes .'><span class="glyphicon ' . esc_attr( $item->attr_title ) . '"></span>&nbsp;';
        else
            $item_output .= '<a'. $attributes .'>';

        $item_output .= $args->link_before . apply_filters( 'the_title', $item->title, $item->ID ) . $args->link_after;
        $item_output .= ( $args->has_children && 0 === $depth ) ? ' <span class="caret"></span></a>' : '</a>';
        $item_output .= $args->after;

        $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
    }
}


public function display_element( $element, &$children_elements, $max_depth, $depth, $args, &$output ) {
    if ( ! $element )
        return;

    $id_field = $this->db_fields['id'];

    // Display this element.
    if ( is_object( $args[0] ) )
       $args[0]->has_children = ! empty( $children_elements[ $element->$id_field ] );

    parent::display_element( $element, $children_elements, $max_depth, $depth, $args, $output );
}


public static function fallback( $args ) {
    if ( current_user_can( 'manage_options' ) ) {

        extract( $args );

        $fb_output = null;

        if ( $container ) {
            $fb_output="<" . $container;

            if ( $container_id )
                $fb_output .= ' id="' . $container_id . '"';

            if ( $container_class )
                $fb_output .= ' class="' . $container_class . '"';

            $fb_output .= '>';
        }

        $fb_output .= '<ul';

        if ( $menu_id )
            $fb_output .= ' id="' . $menu_id . '"';

        if ( $menu_class )
            $fb_output .= ' class="' . $menu_class . '"';

        $fb_output .= '>';
        $fb_output .= '<li><a href="' . admin_url( 'nav-menus.php' ) . '">Add a menu</a></li>';
        $fb_output .= '</ul>';

        if ( $container )
            $fb_output .= '</' . $container . '>';

        echo $fb_output;
        }
    }
}

Then call the navwalker in your menu array like so

<?php /* Primary navigation */
  wp_nav_menu( array(
    'menu' => 'top navigation',
    'depth' => 2,
    'container' => false,
    'menu_class' => 'nav navbar-nav',
    'theme_location' => 'main-nav',             // where it's located in the theme
    //Process nav menu using our custom nav walker
    'walker' => new wp_bootstrap_navwalker())
  );
  ?>

Code source https://github.com/twittem/wp-bootstrap-navwalker