运行应用程序时，Android ListView不显示任何内容

Question

我正在尝试显示产品列表，但是当我运行应用程序时，它确实在设备上显示任何内容。我无法弄清楚我的问题在哪里。我想在MainActivity.java上填充数据。

MainActivity.java

TwoDimensionalShape* ptr_shape = dynamic_cast<TwoDimensionShape*>(object);
if(ptr_shape)
{
    ptr_shape->getPerimeter(/*arguments here if you have them...*/)
}

ProductListAdapater.java

public class MainActivity extends AppCompatActivity {

//    ProductsListAdapter productsListAdapter;

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


        ListView productlistview = (ListView) findViewById(R.id.productlistview);
//        productsListAdapter = new ProductsListAdapter()
//        productlistview.setAdapter(productsListAdapter);

    }

    private List<Product> createListofProducts(){
        ArrayList<Product> productArrayList = new ArrayList<Product>();

        productArrayList.add(new Product("Kimbo", 50.0, 0, " "));

        productArrayList.add(new Product("Sugar", 60.0, 0, " "));

        productArrayList.add(new Product("Oil", 70.0, 0, " "));

        productArrayList.add(new Product("Bread", 40.0, 0, " "));

        productArrayList.add(new Product("water", 30.0, 0, " "));

        return productArrayList;
    }
}

Answer 1

这样的事情怎么样？

ListView productlistview = (ListView) findViewById(R.id.productlistview);
productsListAdapter = new ProductsListAdapter(this, createListofProducts())
productlistview.setAdapter(productsListAdapter);