compareTo()和equals()
import java.math.*;
import java.util.*;
public class Main {
public static void main(String []args){
Scanner cin = new Scanner (System.in);
BigInteger a,b,c,d;
a=cin.nextBigInteger();
b=cin.nextBigInteger();
c=cin.nextBigInteger();
d=cin.nextBigInteger();
if(a.compareTo(b)<0)//此时由于a<b,则返回值小于0;
{
System.out.println("a<b");
}
if(b.equals(c))//此时由于b==c,则返回值等于0;
{
System.out.println("b==c");
}
if(d.compareTo(c)>0)//此时由于d>c,则返回值大于0;
{
System.out.println("d>c");
}
}
}