Integer.parseInt(String str) java.lang.NumberFormatException: Errors

Question

I keep getting number format expectations, even though I'm trimming the strings and they don't contain non numerical characters bizarrely it works for some numbers and not others. Below is an example of a string I get number format exception for. Also, any string starting with 0 e.g "0208405223", is returned 208405223, there's no zero anymore is that supposed to happen?

String n="3020857508";
Integer a = Integer.parseInt(n.trim());
System.out.println(a);

This is the exception:

Exception in thread "main" java.lang.NumberFormatException: For input string: "3020857508"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:583)
    at java.lang.Integer.parseInt(Integer.java:615)
    at JavaBeans.Main.main(Main.java:15)

Solution 1

It's because 3020857508 exceeds Integer.MAX_VALUE. You should use long to convert the string to number.

java> String n="3020857508";
//=> java.lang.String n = "3020857508"
java> Integer a = Integer.parseInt(n.trim());
//=> java.lang.NumberFormatException: For input string: "3020857508"
java> Integer.MAX_VALUE
//=> java.lang.Integer res2 = 2147483647
java> Long a = Long.parseLong(n.trim());
//=>java.lang.Long a = 3020857508

The above is javarepl output.

If you are using JDK9 or above, you can see the same result in jshell.

jshell> String n="3020857508"
n ==> "3020857508"

jshell> Integer a = Integer.parseInt(n.trim())
|  Exception java.lang.NumberFormatException: For input string: "3020857508"
|        at NumberFormatException.forInputString (NumberFormatException.java:65)
|        at Integer.parseInt (Integer.java:652)
|        at Integer.parseInt (Integer.java:770)
|        at (#2:1)

jshell> Integer.MAX_VALUE
$3 ==> 2147483647

jshell> Long a = Long.parseLong(n.trim());
a ==> 3020857508

Solution 2

The largest number parseable as an int is 2147483647 (2³¹-1), and the largest long is 9223372036854775807 (2⁶³-1), only about twice as long.

To parse arbitrarily long numbers, use:

import java.math.BigInteger;

BigInteger number = new BigInteger(str);

Solution 3

MAX_INT is 2147483647 and you're trying to parse a bigger number as Integer.

You can use Long.parseLong instead:

System.out.println(Long.parseLong("3020857508")); // 3020857508