BigDecimal's addition, subtraction, multiplication and division, size comparison, rounding up and down, and BigDecimal's set accumulation, judge whether BigDecimal has decimal

In fact, online about Bigdecimal There are many documents about the operation of , Here is a summary , Put these routine operations into a document , For future viewing

Bigdecimal Addition, subtraction, multiplication and division

BigDecimal b1 = new BigDecimal("10");
BigDecimal b2 = new BigDecimal("5");
BigDecimal b3 = null;

// Add 
b3 = b1.add(b2);
System.out.println("b1 + b2 =" + b3);// Output 15

// Subtraction 
b3 = b1.subtract(b2);
System.out.println("b1 - b2 = " + b3);// Output 5

// Multiplication 
b3 = b1.multiply(b2);
System.out.println("b1 * b2 = " + b3);// Output 50

// division 
b3 = b1.divide(b2);
System.out.println("b1 / b2 = " + b3);// Output 2

Bigdecimal Compare the size of

BigDecimal a = new BigDecimal("10");
BigDecimal b = new BigDecimal("5");

if(a.compareTo(b) == -1){
    
    System.out.println("a Less than b");
}

 if(a.compareTo(b) == 0){
    
     System.out.println("a be equal to b");
 }

 if(a.compareTo(b) == 1){
    
     System.out.println("a Greater than b");
 }

 if(a.compareTo(b) > -1){
    
     System.out.println("a Greater than or equal to b");
 }

 if(a.compareTo(b) < 1){
    
     System.out.println("a Less than or equal to b");
 }

Bigdecimal Rounding up and rounding down

BigDecimal a = new BigDecimal("0.9");
System.out.println(" Rounding down ：" + a.setScale(0,BigDecimal.ROUND_FLOOR));

BigDecimal b = new BigDecimal("0.1");
System.out.println(" Rounding up ：" + b.setScale(0,BigDecimal.ROUND_UP));

Judge BigDecimal Is there a decimal

BigDecimal b = new BigDecimal(20.5);
if (new BigDecimal(b.intValue()).compareTo(b) != 0) {
    
	System.out.println("b  Is the decimal ");
} else {
    
	System.out.println("b  Is an integer ");
}

Bigdecimal Set accumulation of

image Bigdecimal Cumulative scenes are rare , Although not common , But there will be , unfortunately , I'll use it today （ Smile to cry ~）, So also record this .

There are two scenarios , One is that the set is directly Bigdecimal Of , as follows

 List<BigDecimal> list = new ArrayList<>();

Another is in the form of set objects , Then there are Bigdecimal Properties of type , as follows

List<Employee> list = new ArrayList<>();

// You can see Employee There is an attribute in the class salary, The type is Bigdecimal

@Data
public class Employee {
    
    private int id;
    private String name;
    private int age;
    private BigDecimal salary;
}

Accumulation method of scenario one

List<BigDecimal> list = new ArrayList<>();
list.add(new BigDecimal("1"));
list.add(new BigDecimal("2"));
list.add(new BigDecimal("3"));

BigDecimal decimal = list.stream().reduce(BigDecimal.ZERO, BigDecimal::add);
System.out.println(decimal);  // Output 6

Accumulation method of scenario 2 ： Get... From the object

List<Employee> list = new ArrayList<>();

list.add(new Employee(1," Wang ba ",BigDecimal.valueOf(5)));
list.add(new Employee(2," Chu Yuan ",BigDecimal.valueOf(10)));

BigDecimal result = list.stream()
     //  take Employee Object's salary out  map Return to Bigdecimal
     .map(Employee::getSalary)
     //  Use reduce() Aggregate functions , Implement accumulator 
     .reduce(BigDecimal.ZERO,BigDecimal::add);

System.out.println(result);// Output 15

The above two methods mainly use JDK8 In new features Stream, If you don't understand, you can check this article ：JDK8 New characteristics - Detailed explanation

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because Bigdecimal Similar ones are commonly used in actual development , Make a special note to deepen your influence , Of course , If it helps you , It's also my pleasure ~