获取空值?

1l5u6lss  于 2021-06-29  发布在  Java
关注(0)|答案(2)|浏览(245)

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21天前关门了。
改进这个问题
在这个项目中,getimagelist()方法在正确的位置传递正确的值之后,返回null值。我还做了一些日志来验证它。
请看一下。
代码如下:

public class GalleryImage extends AppCompatActivity {

private ArrayList<StoryModel> arrayList;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_gallery_image);

ListView listView = findViewById(R.id.galleryListView);
Intent intent = getIntent();

String file = intent.getStringExtra("fileName");
String[] files = intent.getStringArrayExtra("filesName");

StoryModel model;

GalleryImage image = new GalleryImage();
arrayList = new ArrayList<>();

for (String s : files) {
    model = new StoryModel();
    String concat = file + "/" + s;
    model.setPath(concat);
    arrayList.add(model);
    Log.i(TAG, "onCreate: Path " + model.getPath());
    Log.i(TAG, "onCreate: ArrayList " + arrayList.add(model));
    Log.i(TAG, "onCreate: getImageList: " + image.getImageList());
}

CustomAdapter galleryAdapter = new CustomAdapter(GalleryImage.this, R.layout.whatsapp_gallery_image, image.getImageList(), files);
listView.setAdapter(galleryAdapter);
}

private ArrayList<StoryModel> getImageList() {
return arrayList;
}

}

这是logcat:

2020-12-16 23:39:06.082 2628-2628/com.example.whatsappstatusdownloader I/GalleryImage: onCreate: Path /storage/emulated/0/WhatsApp Status Downloader/0914b4b418414982960aabe18f718e1d.jpg

2020-12-16 23:39:06.082 2628-2628/com.example.whatsappstatusdownloader I/GalleryImage: onCreate: ArrayList true

2020-12-16 23:39:06.082 2628-2628/com.example.whatsappstatusdownloader I/GalleryImage: onCreate: getImageList: null

2020-12-16 23:39:06.083 2628-2628/com.example.whatsappstatusdownloader I/GalleryImage: onCreate: Path /storage/emulated/0/WhatsApp Status Downloader/bf51fb0d3efa4ec89b71b86bfe0534f9.jpg

2020-12-16 23:39:06.083 2628-2628/com.example.whatsappstatusdownloader I/GalleryImage: onCreate: ArrayList true

2020-12-16 23:39:06.083 2628-2628/com.example.whatsappstatusdownloader I/GalleryImage: onCreate: getImageList: null
q7solyqu

q7solyqu1#

注意代码中的arraylist声明。你有两个。在oncreate中,您可以这样声明:

arrayList = new ArrayList<>();

然后填充此列表,而image.getimagelist()返回另一个示例:

private ArrayList<StoryModel> arrayList;
igsr9ssn

igsr9ssn2#

你创造形象。但你什么都不加。所以,它将完全返回null

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