init

source/src/main/model/Amount.java

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+package model;
+
+/**
+ * Represents a monetary amount. Immutable; all arithmetic returns new instances.
+ */
+public class Amount {
+    private final double value;
+
+    /**
+     * Creates an Amount with the specified value.
+     *
+     * @param value The monetary value.
+     */
+    public Amount(double value) {
+        this.value = value;
+    }
+
+    /**
+     * Returns a new Amount that is the sum of this amount and the given amount.
+     *
+     * @param other The amount to add.
+     * @return A new Amount representing the sum.
+     */
+    public Amount add(Amount other) {
+        return new Amount(this.value + other.value);
+    }
+
+    /**
+     * Returns a new Amount that is the difference of this amount minus the given amount.
+     *
+     * @param other The amount to subtract.
+     * @return A new Amount representing the difference.
+     */
+    public Amount subtract(Amount other) {
+        return new Amount(this.value - other.value);
+    }
+
+    /**
+     * Returns the raw numeric value of this amount.
+     *
+     * @return The monetary value as a double.
+     */
+    public double getValue() {
+        return value;
+    }
+
+    /**
+     * Returns a formatted string representation of this amount.
+     *
+     * @return A string in the form {@code "123.45 SEK"}.
+     */
+    @Override
+    public String toString() {
+        return String.format("%.2f SEK", value);
+    }
+}