使用Account对象输入和输出浮点数。
import java.util.Scanner; public class Main {//N o w J a v a . c o m - 时 代 Java public static void main(String[] args) { Account account1 = new Account("James Bond", 50.00); Account account2 = new Account("Michael Bates", -7.53); // display initial balance of each object System.out.printf("%s balance: $%.2f%n", account1.getName(), account1.getBalance()); System.out.printf("%s balance: $%.2f%n%n", account2.getName(), account2.getBalance()); // create a Scanner to obtain input from the command window Scanner input = new Scanner(System.in); /* n o w j a v a . c o m - 时 代 Java 提供 */ System.out.print("Enter deposit amount for account1: "); // prompt double depositAmount = input.nextDouble(); // obtain user input System.out.printf("%nadding %.2f to account1 balance%n%n", depositAmount); account1.deposit(depositAmount); // add to account1's balance // display balances System.out.printf("%s balance: $%.2f%n", account1.getName(), account1.getBalance()); System.out.printf("%s balance: $%.2f%n%n", account2.getName(), account2.getBalance()); System.out.print("Enter deposit amount for account2: "); // prompt depositAmount = input.nextDouble(); // obtain user input System.out.printf("%nadding %.2f to account2 balance%n%n", depositAmount); account2.deposit(depositAmount); // add to account2 balance // display balances System.out.printf("%s balance: $%.2f%n", account1.getName(), account1.getBalance()); System.out.printf("%s balance: $%.2f%n%n", account2.getName(), account2.getBalance()); } } class Account { private String name; // instance variable private double balance; // instance variable // Account constructor that receives two parameters public Account(String name, double balance) { this.name = name; // assign name to instance variable name // validate that the balance is greater than 0.0; if it's not, // instance variable balance keeps its default initial value of 0.0 if (balance > 0.0) // if the balance is valid this.balance = balance; // assign it to instance variable balance } // method that deposits (adds) only a valid amount to the balance public void deposit(double depositAmount) { if (depositAmount > 0.0)