diff -r 251d0ed461fb -r 58ec6da75f6f task4/solution07/src/org/apidesign/apifest08/currency/MonetaryAmount.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/task4/solution07/src/org/apidesign/apifest08/currency/MonetaryAmount.java	Sat Oct 11 23:38:46 2008 +0200
@@ -0,0 +1,89 @@
+package org.apidesign.apifest08.currency;
+
+import java.math.BigDecimal;
+import java.util.Currency;
+
+/**
+ * An amount of a currency.
+ * Immutable.
+ * @author jdvorak
+ */
+public class MonetaryAmount {
+
+    private final BigDecimal amount;
+    private final Currency currency;
+    
+    /**
+     * A new amount.
+     * @param amount the quantity of the currency; must not be null
+     * @param currency the currency; must not be null
+     */
+    public MonetaryAmount( final BigDecimal amount, final Currency currency ) {
+        this.amount = amount;
+        this.currency = currency;
+        if ( amount == null ) {
+            throw new NullPointerException( "The amount" );
+        }
+        if ( currency == null ) {
+            throw new NullPointerException( "The currency" );
+        }
+    }
+    
+    /**
+     * A new amount.
+     * @param amount the quantity of the currency; must not be null
+     * @param currency the currency; must not be null
+     */
+    public MonetaryAmount( final double amount, final Currency currency ) {
+        this( new BigDecimal( amount ), currency );
+    }
+    
+    /**
+     * The amount.
+     * @return the amount
+     */
+    public BigDecimal getAmount() {
+        return amount;
+    }
+    
+    /**
+     * The currency.
+     * @return the currency
+     */
+    public Currency getCurrency() {
+        return currency;
+    }
+
+    /**
+     * The string representation of the monetary amount.
+     * @return the amount, a non-breakable space, the currency
+     */
+    @Override
+    public String toString() {
+        return amount.toPlainString() + "\u00a0" + currency.toString();
+    }
+    
+    /**
+     * Two monetary amounts are equal to each other iff they have equal amounts of equal currencies.
+     * @param other the other object
+     * @return equality
+     */
+    @Override
+    public boolean equals( final Object other ) {
+        if ( other instanceof MonetaryAmount ) {
+            final MonetaryAmount otherMonetaryAmount = (MonetaryAmount) other;
+            return getAmount().equals( otherMonetaryAmount.getAmount() ) && getCurrency().equals( otherMonetaryAmount.getCurrency() );
+        }
+        return false;
+    }
+    
+    /**
+     * The hash code combines the hash codes of the amount and of the currency.
+     * @return hash code
+     */
+    @Override
+    public int hashCode() {
+        return amount.hashCode() * 37 + currency.hashCode();
+    }
+    
+}