Example 3: Third component using expectations

ExpectationsExample.java

package thirdcomponent;

import java.math.BigDecimal;
import java.math.MathContext;

public class ExpectationsExample {

  public static void main(String[] args) {
    final BigDecimal one = BigDecimal.ONE;
    final BigDecimal three = BigDecimal.valueOf(3L);
    final ExpectationsExample comp = new ExpectationsExample(
        MathContext.DECIMAL32);
    System.out.println(comp.calculate(one, three));
    // prints 0.3333333
  }

  // provided, external choice
  // final as we don't allow ad hoc changes
  // value is dictated by environment, not managed by instance
  private final MathContext c;

  public ExpectationsExample(MathContext mc) {
    this.c = mc;
  }

  public BigDecimal calculate(BigDecimal x, BigDecimal y) {
    return x.divide(y, c);
  }
}