Java正则表达式1=1

I need to look for java regex pattern that finds input string in the format of 1=1 where prefix of "=" should have same count of digits with the suffix. Also here both prefix & suffix values should be the same like 1=1, 11=11, 223=223. Values like 1=2, 3=22, 33=22 should not match the patternI need to look for java regex pattern that find