parse long to negative number

Question

code:

public class Main{
    public static void main(String[] a){
        long t=24*1000*3600;
        System.out.println(t*25);
        System.out.println(2         


        

Answer 1

If you want to do mathematical operations with large numerical values without over flowing, try the BigDecimal class.

Let's say I want to multiply

200,000,000 * 2,000,000,000,000,000,000L * 20,000,000

int testValue = 200000000;
System.out.println("After Standard Multiplication = " +
                                                       testValue * 
                                                       2000000000000000000L * 
                                                       20000000);

The value of the operation will be -4176287866323730432, which is incorrect.

By using the BigDecimal class you can eliminate the dropped bits and get the correct result.

int testValue = 200000000;        
System.out.println("After BigDecimal Multiplication = " +
                              decimalValue.multiply(
                              BigDecimal.valueOf(2000000000000000000L).multiply(
                              BigDecimal.valueOf(testValue))));

After using the BigDecimal, the multiplication returns the correct result which is

80000000000000000000000000000000000