Grouped notification

gistfile1.txt

static final String CHANNEL_ID = "orders";
static final String GROUP_KEY = "group_orders";

void postGroupedNotifications(Context ctx) {
    NotificationManager nm = ctx.getSystemService(NotificationManager.class);

    if (Build.VERSION.SDK_INT >= 26) {
        NotificationChannel ch = new NotificationChannel(
            CHANNEL_ID, "Orders", NotificationManager.IMPORTANCE_DEFAULT);
        nm.createNotificationChannel(ch);
    }

    Notification child1 = new NotificationCompat.Builder(ctx, CHANNEL_ID)
        .setSmallIcon(R.drawable.ic_notification)
        .setContentTitle("注文 #1001")
        .setContentText("出荷準備中")
        .setGroup(GROUP_KEY)
        .build();

    Notification child2 = new NotificationCompat.Builder(ctx, CHANNEL_ID)
        .setSmallIcon(R.drawable.ic_notification)
        .setContentTitle("注文 #1002")
        .setContentText("支払い確認済み")
        .setGroup(GROUP_KEY)
        .build();

    Notification summary = new NotificationCompat.Builder(ctx, CHANNEL_ID)
        .setSmallIcon(R.drawable.ic_notification)
        .setContentTitle("注文の更新（2）")
        .setStyle(new NotificationCompat.InboxStyle()
            .addLine("注文 #1001: 出荷準備中")
            .addLine("注文 #1002: 支払い確認済み")
            .setSummaryText("ショップ名"))
        .setGroup(GROUP_KEY)
        .setGroupSummary(true)
        .build();

    nm.notify(1001, child1);
    nm.notify(1002, child2);
    nm.notify(9999, summary);
}