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我正在尝试将电话号码作为字符串从 Dynamodb 加载，但它显示 NullPointer 错误

这是我试图记录数据的我的活动代码

public class TokenActivity extends Activity {
    DynamoDBMapper dynamoDBMapper;
    @Override
    public void onCreate(final Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_hello_token);

        AWSMobileClient.getInstance().initialize(this).execute();
        AWSCredentialsProvider credentialsProvider = AWSMobileClient.getInstance().getCredentialsProvider();
        AWSConfiguration configuration = AWSMobileClient.getInstance().getConfiguration();


        AmazonDynamoDBClient dynamoDBClient = new AmazonDynamoDBClient(credentialsProvider);

        this.dynamoDBMapper = DynamoDBMapper.builder()
                .dynamoDBClient(dynamoDBClient)
                .awsConfiguration(configuration)
                .build();


        readName();
    }

    public void readName() {
        new Thread(new Runnable() {
            @Override
            public void run() {

                LoginCredentialsDO newsItem = dynamoDBMapper.load(
                        LoginCredentialsDO.class,
                        "userId",
                        "Phone Number");
                // Item read
                  Log.d("News Item:", newsItem.getPhoneNumber());
            }
        }).start();
    }

和 LoginCredentialsDO 包含从数据库中检索数据的方法。

块引用

public class LoginCredentialsDO {
    private String _userId;
    private String _phoneNumber;
    private String _emailId;
    private String _name;

    @DynamoDBHashKey(attributeName = "userId")
    @DynamoDBAttribute(attributeName = "userId")
    public String getUserId() {
        return _userId;
    }

    public void setUserId(final String _userId) {
        this._userId = _userId;
    }
    @DynamoDBRangeKey(attributeName = "Phone Number")
    @DynamoDBAttribute(attributeName = "Phone Number")
    public String getPhoneNumber() {
        return _phoneNumber;
    }

    public void setPhoneNumber(final String _phoneNumber) {
        this._phoneNumber = _phoneNumber;
    }
    @DynamoDBAttribute(attributeName = "Email Id")
    public String getEmailId() {
        return _emailId;
    }

    public void setEmailId(final String _emailId) {
        this._emailId = _emailId;
    }
    @DynamoDBAttribute(attributeName = "Name")
    public String getName() {
        return _name;
    }

    public void setName(final String _name) {
        this._name = _name;
    }

}

我收到 NullPointer 异常错误

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.....LoginCredentialsDO.getPhoneNumber()' on a null object reference
        at com......TokenActivity$4.run(TokenActivity.java:153)
        at java.lang.Thread.run(Thread.java:764)

谁能解释为什么我得到空点错误，因为我已经定义了所有变量并且我正在访问的数据库项也不为空？

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0 回答 0