Can I use a charger with the following values:
Input 100-240V 1.5A Output 19V 2.40A
Input 100-240V 1.6A Output 19V 3.42A
First, you need to check what your device REQUIRES.
If the device requires a steady 3.42 amps and you're providing only 2.4 amps max, then the device (laptop?) will attempt to pull more current than the PSU was equipped for. Which could result in PSU failure, laptop failure or even worse, a fire.
Now, assuming the device ONLY needs to pull 19V and 2 amps, then you are within spec. And that would probably be OK. But I always prefer a safety margin. If a device requires 2 amps I like to make sure the PSU can provide 3 or more.
NEVER assume that because two power supplies fit, are from the same manufacturer, etc. that it is safe to use.
ALWAYS ALWAYS check the specs on the device you're needing to power.
A similar question, at one point marked as a duplicate, focuses on a voltage difference between the original charger and a replacement. The answers on that one do a good job of addressing that issue. Here you're talking about 1/3 lower current rating, which is a different issue.
The current rating is a capacity. The charger will supply only what the device requires, up to the rated capacity. You don't need to worry about a charger with a higher current rating, but a lower rating might, or might not, be a problem.
The chargers are often "generic", designed to work with a range of models. The capacity of the original might be more than your device needs, in which case the replacement might be fine. In this case, if your device could actually work with a 2.4A charger, the originial would have been nearly 50% more than required, which seems unusual.
The only situation in which you should use a smaller charger is if you can determine that it meets the specifications for the device. Your device should have a sticker on it that shows its power requirements. If the sticker is no longer readable, you may be able to get the information from the user manual or the manufacturer's web site. The replacement must meet or exceed the device's amperage requirement.
If you use an inadequate charger, you will overload it, which could damage the charger or cause its overload protection to shut it down. Even if it does work, you would probably be unable to both charge the battery and power the device simultaneously. The charger would also run very hot, which could shorten its life.
If you are unable to determine the laptop's power requirements, go one of two routes: