I've made a player "springboard" that launches them into the air. I want to log the player's velocity every 5 ticks and log it all neatly in a text file after which you could plug the data in Logger Pro and graph it. I am having trouble doing this and as a novice programmer have this mess below:

 

public void onLanded(World worldIn, Entity entityIn)
	    {
	        if (entityIn.isSneaking())
	        {
	            super.onLanded(worldIn, entityIn);
	        }
	        else if (entityIn.motionY < 0.0D)
	        {
	        	entityIn.motionY = 2;
	        	entityIn.motionX = 0;
	        		        	
	        	try{
					File file = new File("data_log.txt"); 
				
					if(!file.exists()) {
						file.createNewFile();
					}
				FileWriter fw = new FileWriter(file); 
				PrintWriter pw = new PrintWriter(fw);

				pw.println(entityIn.motionY);
				//World world = Minecraft.getMinecraft().world;
				
				//double start = world.getTotalWorldTime();
				//while(entityIn.motionY != 0) {
				//if(world != null && (world.getWorldTime() - start) % 5 == 0) {
					pw.println(entityIn.motionY);
				//}
				//}
				pw.close();
				
	        	}
				
				catch(IOException e) {e.printStackTrace();}

	            if (!(entityIn instanceof EntityLivingBase))
	            {
	            	entityIn.motionY *= 0.0D;
                }}}

 

~The commented sections cause a crash~

Block#onLanded will be called on the server side.

Calling Minecraft.getMinecraft().world on the server side will cause a crash.

Instead, you should use the instance of World given in the parameter of Block#onLanded.

Edited May 27, 20196 yr by DavidM

Thank for you for your response; I followed your advice. On execution, however, the while loop produced, for a few seconds before crashing, a 1.57GB file filled with lines stating the player's initial assigned velocity (2.0). To fix this, I think I would like to have this velocity measurement run every 5 ticks or so. I've read about Forge's TickEvent - I frankly don't know how to use it though.

 

Here is my code:

 

	    public void onLanded(World worldIn, Entity entityIn)
	    {
	        if (entityIn.isSneaking())
	        {
	            super.onLanded(worldIn, entityIn);
	        }
	        else if (entityIn.motionY < 0.0D)
	        {
	        	entityIn.motionY = 2;
	        	entityIn.motionX = 0;
	        		        	
	        	try{
					File file = new File("data_log.txt"); 
				
					if(!file.exists()) {
						file.createNewFile();
					}
				FileWriter fw = new FileWriter(file); 
				PrintWriter pw = new PrintWriter(fw);

				double start = worldIn.getTotalWorldTime();
				
				while(entityIn.collidedVertically != true) {
				if(worldIn != null && (worldIn.getWorldTime() - start) % 5 == 0) {
					pw.println(entityIn.motionY);
				}
				}
				pw.close();
				
	        	}
				
				catch(IOException e) {e.printStackTrace();}

	            if (!(entityIn instanceof EntityLivingBase))
	            {
	            	entityIn.motionY *= 0.0D;
	            }
	            }
                }

 

This is not how anything works. While blocks execution untill it resolves(as literally any other statement). 

So not only are you not writing your line each tick(you are writing it as many times a second as your PC can handle actually, whoch explains the size of the log) your loop wouldn't ever exit, so you basically have a while(true) here.

All of this is basic java.

1 hour ago, thisisatest said:

I've read about Forge's TickEvent - I frankly don't know how to use it though.

You MUST use the tick event for this purpose.

https://mcforge.readthedocs.io/en/latest/events/intro/

On 5/27/2019 at 9:19 AM, thisisatest said:

after which you could plug the data in Logger Pro and graph it

Just out of curiosity, are you doing this for physics class (IGCSE Physics or something)?

 

You could mark the player that used the springboard, and in your subscriber for TickEvent.PlayerTickEvent (can't remember the spelling), check if the player if marked by the springboard and log his/her position accordingly.

Edited May 29, 20196 yr by DavidM

 

Edited June 3, 20196 yr by thisisatest