Question

我正在尝试将数据推送到AWS DynamoDB，但我一直面临这个错误：

java.lang.NullPointerException：尝试调用虚方法com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper com.uploadtodatabasevts.amazonaws.AWSMobileClient.getDynamoDBMapper（）＆＃39;在空对象引用上

对于遗漏的内容或错误输入的内容有任何想法吗？我似乎无法找到答案。

以下是nil类：

对于MainActivity，假设它是主键自动增量，但我不知道如何在AWS DynamoDB NoSQL上执行此操作，因此我目前正在手动推送ID。

＆＃13;

outfitID

＆＃13;

以下是AWSMobileClient：

＆＃13;

package com.uploadtodatabasevts;

import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import com.amazonaws.AmazonClientException;
import com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBMapper;
import com.uploadtodatabasevts.amazonaws.AWSMobileClient;
import com.uploadtodatabasevts.amazonaws.DynamoDBUtils;
import com.uploadtodatabasevts.amazonaws.OutfitDO;
import com.uploadtodatabasevts.amazonaws.ThreadUtils;

public class MainActivity extends AppCompatActivity {

    private static final String LOG_TAG = MainActivity.class.getName();
    String pID, pDetails;
    double oID;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        EditText outfitID = (EditText)findViewById(R.id.eTxtOutfitID);


        EditText productID = (EditText)findViewById(R.id.eTxtProductID);
        pID = productID.getText().toString();

        EditText productDetails = (EditText)findViewById(R.id.eTxtProductDetails);
        pDetails = productDetails.getText().toString();

        Button confirm = (Button)findViewById(R.id.btnConfirm);
        confirm.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                insertData();

            }
        });

    }

    private void insertData() throws AmazonClientException {
        final DynamoDBMapper dynamoDBMapper = AWSMobileClient.defaultMobileClient().getDynamoDBMapper();
        final OutfitDO outfitDO = new OutfitDO();

        outfitDO.setOutfitId((double) 10);
        outfitDO.setOutfitId(oID);
        outfitDO.setItemOneId(pID);
        outfitDO.setItemOneDetails(pDetails);
        AmazonClientException lastException = null;

        try {
            dynamoDBMapper.save(outfitDO);
        }  catch (final AmazonClientException ex) {
            Log.e(LOG_TAG, "Failed saving item : " + ex.getMessage(), ex);
            lastException = ex;
        }

        if (lastException != null){
            throw lastException;
        }

    }
}

＆＃13;

Answer 1

您的Application类应具有通过调用AWSMobileClient.initializeMobileClientIfNecessary(context)来初始化移动客户端的代码，否则AWSMobileClient.defaultMobileClient（）将返回null。如果您没有自定义Application类，则可以在Activity的AWSMobileClient.initializeMobileClientIfNecessary(context)生命周期方法中调用onCreate()。

错误 - 尝试调用虚拟方法＆＃39; ＆＃39;在null对象引用上

1 个答案: