如何在没有 NumberFormatException 的情况下将 String 转换为 long？

Question

I want to append these long variables, so I turned them into Strings first. When I return them back into a long it throws a NumberFormatException.

public long BLZ = 12345678l;
public long KNr = 1234567890l;
public String landCode = "1314";
long fedor = Long.parseLong(String.valueOf(BLZ) + String.valueOf(KNr) + 
landCode + "00"); 

Answer 1

long BLZ = 12345678l;
long KNr = 1234567890l;
String landCode = "1314";
System.out.println(Long.MAX_VALUE);
System.out.println(String.valueOf(BLZ) + String.valueOf(KNr) + landCode + "00"); 

leads to the output

9223372036854775807

123456781234567890131400

The number you try to parse in is bigger than a long can handle.

Edit: You asked how to solve your problem. In the comments of your question there is the theory that you want to calculate the checksum of an IBAN. You can do that by using java.math.BigInteger :

System.out.println(Long.MAX_VALUE);
long BLZ = 12345678l;
long KNr = 1234567890l;
String landCode = "1314";
String val = String.valueOf(BLZ) + String.valueOf(KNr) + landCode + "00";
System.out.println(val); 
System.out.println(BigInteger.valueOf(98).subtract(new BigInteger(val).mod(BigInteger.valueOf(97))));

This leads to the following output:

9223372036854775807

123456781234567890131400

87

Alternatively you can check the IBAN Documentation (it's german but that shouldn't be problem for you I suppose ;-) where in chapter 4 there is a description of a way to calculate the checksum if you're limited (like here). You will still need longs to be able to implement that, because 9-digit numbers can exceed the range of an int .