I am having a problem that I don't know how to check if the bucket can pick up the liquid? And I tried this but this only work with bucket that inside Vanilla

for (int i = 0; i < this.craftMatrix.getSlots(); ++i) {
    if (this.craftMatrix.getStackInSlot(i) != null && (this.craftMatrix.getStackInSlot(i).getItem() == Items.WATER_BUCKET || this.craftMatrix.getStackInSlot(i).getItem==Items.LAVA_BUCKET)) {
        this.craftMatrix.setStackInSlot(i, new ItemStack(Items.BUCKET));
    } else {
        this.craftMatrix.extractItem(i, 1, false);
    }
}

 I would greatly appreciated your help!

Use the IFluidHandler capability for fluid-related operations. You can pass false as the second argument of IFluidHandler#fill and IFluidHandler#drain to simulate the filling/draining without actually modifying the contents of the IFluidHandler.