Python: How can I get a loop to break if the value == 'null' shows up multiple times in a row while reading a log?

Reading an android display mode monitor which gives the value of the plugged in resolution. I want the loop to break if it reads "null" multiple times in a row:

Display Mode:  720p60hz                                                                                       
Display Mode:  720p60hz                                                                                       
Display Mode:  null                                                                                       
Display Mode:  null                                                                                       
Display Mode:  null                                                                                       
Display Mode:  null

BREAK! 

CODE

import time
import subprocess

while True:

z = subprocess.getoutput("adb shell cat /sys/class/display/mode")
time.sleep(.1)
print(f'Display Mode:  {z}')

t1 = time.time()
t2 = time.time()
if z == 'null':


print(f't1 is :{t1}')

else:
continue

if z == 'null'
print(f't2 is :{t2}')
print('i am null')

if t2-t1 > .1:
  
  break

>Solution :

Your code is a bit hard to read because the indentation was left out, and indentation is a part of Python syntax.
But here’s my best guess for what you’re looking for:

import time
import subprocess

THRESHOLD_BAD_DISPLAY_READS = 10  # Set this to the number of bad reads in a row that you can tolerate
num_bad_display_reads = 0

while num_bad_display_reads < THRESHOLD_BAD_DISPLAY_READS:
    display_mode = subprocess.getoutput("adb shell cat /sys/class/display/mode")
    time.sleep(.1)
    if display_mode == 'null' or display_mode is None:
        num_bad_display_reads += 1  # Start counting up
    else:
        display_mode = num_bad_display_reads = 0  # Reset the count
        #print(f'Display Mode:  {display_mode}')  # Uncomment this during debugging

# You have now left the display loop. Feel free to do something else.

My guess is that you would like to re-enter the loop if the display recovers. If that’s true, then I recommend that you post some specifics about that in another SO question.

Note: I renamed z to display_mode.