编写帐簿类AccountBook类。类中有三个属性：accountName(String类型)、income(double类型)和outcome(double类型)。定义通过收入和支出自动计算余额的方法compute。再编写测试类，在测试类中用AccoutnBook类创建一个帐簿对象，设置名称是“Zhangsan”，收入30，支出10，并将帐户名称“Zhangsan”，该帐户收入额和支出额及该账户的余额输出到控制台。

public class AccountBook {
    private String accountName;
    private double income;
    private double outcome;
    
    public AccountBook(String accountName, double income, double outcome) {
        this.accountName = accountName;
        this.income = income;
        this.outcome = outcome;
    }
    
    public void compute() {
        double balance = this.income - this.outcome;
        System.out.println("账户余额为：" + balance);
    }
    
    public String getAccountName() {
        return accountName;
    }
    
    public void setAccountName(String accountName) {
        this.accountName = accountName;
    }
    
    public double getIncome() {
        return income;
    }
    
    public void setIncome(double income) {
        this.income = income;
    }
    
    public double getOutcome() {
        return outcome;
    }
    
    public void setOutcome(double outcome) {
        this.outcome = outcome;
    }
}

public class TestAccountBook {
    public static void main(String[] args) {
        AccountBook book = new AccountBook("Zhangsan", 30, 10);
        System.out.println("账户名称：" + book.getAccountName());
        System.out.println("收入额：" + book.getIncome());
        System.out.println("支出额：" + book.getOutcome());
        book.compute();
    }
}