如何使用 ArrayAdapter 在 ArrayList 中的 ListView 中显示项目（图像的路径）？

Posted 2023-04-19

【中文标题】如何使用 ArrayAdapter 在 ArrayList 中的 ListView 中显示项目（图像的路径）？

【英文标题】：How to display items (paths of images) in ListView from ArrayList using ArrayAdapter?

【发布时间】：2020-05-01 15:55:47

【问题描述】：

如何使用 ArrayAdapter 从 ArrayList 在 ListView 中显示项目（图像的路径）？我的代码不起作用 - 它不打印图像路径列表。

public class MainActivity extends Activity 

    ImageView imageView;
    Button button;

    private static final int PICK_IMAGE = 100;
    Uri imageUri;

    ArrayList<String> urllist = new ArrayList<>();
    ListView list;

    TextView tv;

    @Override
    public void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imageView = (ImageView)findViewById(R.id.imageView);
        button = (Button)findViewById(R.id.buttonLoadPicture);
        list = (ListView) findViewById(R.id.list);
        //tv=(TextView) findViewById(R.id.tv);

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, urllist);
        list.setAdapter(adapter);

        button.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View v) 
                openGallery();

            
        );
    
    private void openGallery() 
        Intent gallery = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.INTERNAL_CONTENT_URI);
        startActivityForResult(gallery, PICK_IMAGE);
    
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data)
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK && requestCode == PICK_IMAGE)
            imageUri = data.getData();
            imageView.setImageURI(imageUri);
            String name = data.getData().getPath();
            urllist.add(name); //here I add each path to list
            //tv.setText(TextUtils.concat(tv.getText(), " ", name));
            Toast.makeText(this, name, Toast.LENGTH_SHORT).show();
        
    

【问题讨论】：

也许你必须调用 notifyDataSetChanged 方法

【参考方案1】：

在更新urllist 时，您还需要通知适配器。为此，请将您的 adapter 改为一个字段。

那么当您向urllist 添加项目时，别忘了致电adapter.notifyDataSetChanged()。

ArrayList<String> urllist = new ArrayList<>();

// Make adapter a field
ArrayAdapter<String> adapter;

@Override
public void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // ...

    adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, urllist);
    list.setAdapter(adapter);

    // ...


@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
    super.onActivityResult(requestCode, resultCode, data);
    if (resultCode == RESULT_OK && requestCode == PICK_IMAGE)
        // ...

        urllist.add(name); //here I add each path to list
        // Notify the adapter
        adapter.notifyDataSetChanged();
    

【参考方案2】：

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
    super.onActivityResult(requestCode, resultCode, data);
    if (resultCode == RESULT_OK && requestCode == PICK_IMAGE)
        imageUri = data.getData();
        imageView.setImageURI(imageUri);

        String name = data.getData().getPath();
        urllist.add(name); //here I add each path to list
        Toast.makeText(this, name, Toast.LENGTH_SHORT).show();

        // assign urllist to adapter      
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, urllist);
        list.setAdapter(adapter);