Since an infinite string is converted into an integer, it must be a string composed of numbers. In Java, if a number is too big, you can consider using large number operation. There is a BigInteger class in the java.math package, which is used to calculate very large numbers. The specific method is: firstly, import the java.math package by importing java.math.biginteger; Secondly, you need to define a BigInteger object. The method is BigInteger Big1= New BigInteger ("infinite number to be operated"). This will convert an infinite number into an integer. Of course, you can also define a second BigInteger object, so that you can convert the second infinite number into integers, and then use the addition, subtraction, multiplication and division methods provided in the BigInteger class to operate on these infinite numbers (the specific addition, subtraction, multiplication and division methods can be found in the java.math package in the API).