How to use comparison operators like >, =, < on

Question

I have a domain class with unitPrice set as BigDecimal data type. Now I am trying to create a method to compare price but it seems like I can't have comparison operators in BigDecimal data type. Do I have to change data type or is there other way around?

Answer 1

BigDecimal isn't a primitive, so you cannot use the <, > operators. However, since it's a Comparable, you can use the compareTo(BigDecimal) to the same effect. E.g.:

public class Domain {
    private BigDecimal unitPrice;

    public boolean isCheaperThan(BigDecimal other) {
        return unitPirce.compareTo(other.unitPrice) < 0;
    }

    // etc...
}

Answer 2

You can use method named compareTo, x.compareTo(y). It will return 0 if x and y are equal, 1 if x is greater than y and -1 if x is smaller than y

Answer 3

Use the compareTo method of BigDecimal :

public int compareTo(BigDecimal val) Compares this BigDecimal with the specified BigDecimal.

Returns:
-1, 0, or 1 as this BigDecimal is numerically less than, equal to, or greater than val.

Answer 4

Every object of the Class BigDecimal has a method compareTo you can use to compare it to another BigDecimal. The result of compareTo is then compared > 0, == 0 or < 0 depending on what you need. Read the documentation and you will find out.

The operators ==, <, > and so on can only be used on primitive data types like int, long, double or their wrapper classes like Integerand Double.

From the documentation of compareTo:

Compares this BigDecimal with the specified BigDecimal.

Two BigDecimal objects that are equal in value but have a different scale (like 2.0 and 2.00) are considered equal by this method. This method is provided in preference to individual methods for each of the six boolean comparison operators (<, ==, >, >=, !=, <=). The suggested idiom for performing these comparisons is: (x.compareTo(y) <op> 0), where <op> is one of the six comparison operators.

Returns: -1, 0, or 1 as this BigDecimal is numerically less than, equal to, or greater than val.

Answer 5

To be short:

firstBigDecimal.compareTo(secondBigDecimal) < 0 // "<"
firstBigDecimal.compareTo(secondBigDecimal) > 0 // ">"    
firstBigDecimal.compareTo(secondBigDecimal) == 0 // "=="  
firstBigDecimal.compareTo(secondBigDecimal) >= 0 // ">="    

Answer 6

Here is an example for all six boolean comparison operators (<, ==, >, >=, !=, <=):

BigDecimal big10 = new BigDecimal(10);
BigDecimal big20 = new BigDecimal(20);

System.out.println(big10.compareTo(big20) < -1);  // false
System.out.println(big10.compareTo(big20) <= -1); // true
System.out.println(big10.compareTo(big20) == -1); // true
System.out.println(big10.compareTo(big20) >= -1); // true
System.out.println(big10.compareTo(big20) > -1);  // false
System.out.println(big10.compareTo(big20) != -1); // false

System.out.println(big10.compareTo(big20) < 0);   // true
System.out.println(big10.compareTo(big20) <= 0);  // true
System.out.println(big10.compareTo(big20) == 0);  // false
System.out.println(big10.compareTo(big20) >= 0);  // false
System.out.println(big10.compareTo(big20) > 0);   // false
System.out.println(big10.compareTo(big20) != 0);  // true

System.out.println(big10.compareTo(big20) < 1);   // true
System.out.println(big10.compareTo(big20) <= 1);  // true
System.out.println(big10.compareTo(big20) == 1);  // false
System.out.println(big10.compareTo(big20) >= 1);  // false
System.out.println(big10.compareTo(big20) > 1);   // false
System.out.println(big10.compareTo(big20) != 1);  // true