// package inheritance;

public interface Asset {
	
	// how much the asset is worth
	public double getMarketValue();

	// how much money has been made on this asset
	public double getProfit();
}



// package inheritance;

public class Cash implements Asset {
	private double amount; // amount of money held

	// constructs a cash investment of the given amount
	public Cash(double amount) {
		this.amount = amount;
	}

	// returns this cash investment's market value, which
	// is equal to the amount of cash
	public double getMarketValue() {
		return amount;
	}

	// since cash is a fixed asset, it never has any profit
	public double getProfit() {
		return 0.0;
	}

	// sets the amount of cash invested to the given value
	public void setAmount(double amount) {
		this.amount = amount;
	}

	// this method overrides the equals method in the Object class
	@Override
	public boolean equals(Object obj) {

		if (obj == null) {
			return false;
		}

		if (obj.getClass() != this.getClass()) {
			return false;
		}

		final Cash cash = (Cash) obj;
		if (!((Double.valueOf(this.amount)).equals(Double.valueOf(cash.amount)))) {
			return false;
		}

		return true;
	}

	@Override
	public int hashCode() {

		// chose a random prime number for better hash functionality
		int hash = 31;
		hash = 17 * hash + (Double.valueOf(this.amount) != null ? Double.valueOf(this.amount).hashCode() : 0);

		return hash;
	}
	
	
	
	public static void main(String args[]) {
		
		Cash cash = new Cash(452.6);
		Cash cash1 = new Cash(685.56);
		Cash cash2 = new Cash(543.87);
		Cash cash3 = new Cash(685.56);
		
		System.out.println("Are cash and cash2 objects have same values? " + cash.equals(cash2));
		System.out.println("Are cash1 and cash3 objects have same values? " + cash1.equals(cash3));	
	}

}

Output:

Are cash and cash2 objects have same values? false
Are cash1 and cash3 objects have same values? true