HarmonyOS鸿蒙Next中云存储下载文件时出现java.lang.NullPointerException: Attempt to invoke virtual method如何解决

HarmonyOS鸿蒙Next中云存储下载文件时出现java.lang.NullPointerException: Attempt to invoke virtual method如何解决

W/System.err: java.lang.NullPointerException: Attempt to invoke virtual method ‘com.huawei.agconnect.cloud.storage.core.StorageTask com.huawei.agconnect.cloud.storage.core.DownloadTask.addOnSuccessListener(com.huawei.hmf.tasks.OnSuccessListener)’ on a null object reference

W/System.err: at com.lqc.cloud_storage.MainActivity.downloadFile(MainActivity.java:117) at com.lqc.cloud_storage.MainActivity.downloadFile(MainActivity.java:104) at java.lang.reflect.Method.invoke(Native Method)

在这个报错我定位到的错误代码如下：

：

downloadTask.addOnSuccessListener(downloadResult -> mShowResultTv.setText("download success!"))
        .addOnFailureListener(e -> mShowResultTv.setText("download failure!"))
        .addOnProgressListener(downloadResult -> mshowProgerss
                .setText(String.format("progress: %f", (downloadResult.getBytesTransferred()*1.0)/downloadResult.getTotalByteCount()*100)+"%")

是哪里出现了空指针，没找明白

downloadTask明明赋值了，怎么会是空的呢？

下载代码：

private void downloadFile() {
    String fileName = "download_" + System.currentTimeMillis() + ".jpg";
    final String path = "test.jpg";
    String agcSdkDirPath = getAGCSdkDirPath();
    final File file = new File(agcSdkDirPath, fileName);
    StorageReference storageReference = mAGCStorageManagement.getStorageReference(path);
    DownloadTask downloadTask = storageReference.getFile(file);

    try {
        downloadTask.addOnSuccessListener(downloadResult -> mShowResultTv.setText("download success!"))
                .addOnFailureListener(e -> mShowResultTv.setText("download failure!"))
                .addOnProgressListener(downloadResult -> mshowProgerss
                        .setText(String.format("progress: %f", (downloadResult.getBytesTransferred()*1.0)/downloadResult.getTotalByteCount()*100)+"%");
    } catch (Exception e) {
        e.printStackTrace();
    }
}

private String getAGCSdkDirPath() {
    String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/AGCSdk/";
    System.out.println("path=" + path);
    File dir = new File(path);
    if (!dir.exists()) {
        dir.mkdirs();
    }
    return path;
}