Question

我有一个银行账户的Java类示例：

public class Account {
    private Integer accountNumber;
    private Integer authPin;
    private Integer transactionPin;

    public Account(Integer accountNumber, Integer authPin, Integer transactionPin) {
        this.accountNumber = accountNumber;
        this.authPin = authPin;
        this.transactionPin = transactionPin;
    }

    public Integer getAccountNumber() {
        return accountNumber;
    }

    public void setAccountNumber(Integer accountNumber) {
        this.accountNumber = accountNumber;
    }

    public Integer getAuthPin() {
        return authPin;
    }

    public void setAuthPin(Integer authPin) {
        this.authPin = authPin;
    }

    public Integer getTransactionPin() {
        return transactionPin;
    }

    public void setTransactionPin(Integer transactionPin) {
        this.transactionPin = transactionPin;
    }

    @Override
    public String toString() {
        return accountNumber + "," + authPin + "," + transactionPin;
    }

    @Override
    public boolean equals(Object obj) {
        Account account = (Account) obj;
        return (this.accountNumber == account.getAccountNumber() && this.authPin == account.getAuthPin()
                && this.transactionPin == account.getTransactionPin());
    }

    @Override
    public int hashCode() {
        // TODO Auto-generated method stub
        return Objects.hashCode(this.getAccountNumber());
    }
}

从代码片段中可以看出，我已经覆盖了equals（）和hashCode（）方法。但是当我尝试使用jUnit进行简单的断言检查时，它失败了：

public class TestFileIO {
    Account account;

    @Before
    public void setUp() throws Exception {
        account = new Account(7, 2708, 2708);
    }

    @Test
    public void testReadTransactionFile() {
        assertEquals(account, new Account(7, 2708, 2708));
    }

我错过了一些重要的事情吗？

Answer 1

而不是比较Integer对象引用：

return (this.accountNumber == account.getAccountNumber() && this.authPin == account.getAuthPin()
        && this.transactionPin == account.getTransactionPin());

因为，Integer对象引用不等于，例如此断言失败：

// different identities -> this assertion fails
assert new Integer(7) == new Integer(7);

使用.equals：

return (Objects.equals(this.accountNumber, account.getAccountNumber())
        && Objects.equals(this.authPin, account.getAuthPin())
        && Objects.equals(this.transactionPin, account.getTransactionPin()));

如果保证字段永远不会是null，则将其类型更改为int：

private int accountNumber;
private int authPin;
private int transactionPin;

然后您不需要更改equals实现，就像它一样。

@overriding Java类中的equals（）和hashCode（）

1 个答案: