First Table

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Creating Your First Decision Table

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Example Use Case: Shipping Charges

• Free shipping when:
• The order has 4+ items AND the total is $300+
• Standard shipping is selected (4-5 business days)
• Otherwise, shipping charges vary based on:
• Number of items
• Delivery speed (Next day, 2nd day, or Standard)
• Order total (less than $300 or$300+)

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Step 1: Create a New Excel Spreadsheet

1. Open Microsoft Excel® or your preferred spreadsheet application
2. Create a new blank workbook
3. Save it as ShippingCharges.drl.xlsx in your project’s src/main/resources/rules directory.

Important: Starting with Drools v8, file extension must end in either .drl.xls, .drl.xlsx, or .drl.csv

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Step 2: Define the RuleSet Area

1. In cell A1, type a descriptive comment like Shipping Charges Decision Table
2. In cell B1, type RuleSet
3. In cell C1, type com.example.shipping (this will be your rule package name)
4. Move to the next row (row 2)
5. In cell B2, type Import
6. In cell C2, type com.example.model.Order, com.example.model.Charge

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Step 3: Define the First RuleTable

1. Skip a row and in cell B4, type RuleTable followed by a name: RuleTable Shipping Under 300
2. In row 5, define the condition and action headers:
3. Cell B5: CONDITION
4. Cell C5: CONDITION
5. Cell D5: ACTION
6. In row 6, define the object types:
7. Cell B6: $order : Order
8. Cell C6: Order
9. Cell D6: (leave empty)
10. In row 7, define the constraints and actions:
11. Cell B7: total < 300
12. Cell C7: itemsCount == $1, deliverInDays == $2
13. Cell D7: insert(new Charge($param));
14. In row 8, add descriptive column headers:
15. Cell B8: Under $300
16. Cell C8: Items & Delivery
17. Cell D8: Shipping Charge

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Step 4: Create the Second RuleTable

1. Skip a row after the previous table
2. In cell B16, type RuleTable Shipping Over 300
3. Repeat the same headers and descriptive rows as with the first table
4. Change B19 (the constraint) to total >= 300
5. Use the same format for the other condition and action cells

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Step 5: Create the Data Models

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Order.java

package com.example.model;

public class Order {
    private int itemsCount;
    private double total;
    private int deliverInDays;

    public Order() {
    }

    public Order(int itemsCount, double total, int deliverInDays) {
        this.itemsCount = itemsCount;
        this.total = total;
        this.deliverInDays = deliverInDays;
    }

    public int getItemsCount() {
        return itemsCount;
    }

    public void setItemsCount(int itemsCount) {
        this.itemsCount = itemsCount;
    }

    public double getTotal() {
        return total;
    }

    public void setTotal(double total) {
        this.total = total;
    }

    public int getDeliverInDays() {
        return deliverInDays;
    }

    public void setDeliverInDays(int deliverInDays) {
        this.deliverInDays = deliverInDays;
    }
}

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Charge.java

package com.example.model;

public class Charge {
    private double amount;

    public Charge() {
    }

    public Charge(double amount) {
        this.amount = amount;
    }

    public double getAmount() {
        return amount;
    }

    public void setAmount(double amount) {
        this.amount = amount;
    }

    @Override
    public String toString() {
        return "Shipping charge: $" + amount;
    }
}

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Complete Example