Question

我是Android应用程序开发的初学者，在stackoverflow上可能有类似的问题，但我无法找到这个问题的确切解决方案。我在SO上尝试了很多链接。帮助感谢。如果需要上传任何其他文件，请告诉我。

我非常确定这些项目是否已插入列表视图中，因为当我将项目保存为0时，我得到以下输出。Toast.makeText to display item0 of listview l1 因此将数据插入listview没有问题。问题可能在于显示

// fragment_cart layout - where the listview is stored.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical">

<ListView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/listview_cart"
   />
</LinearLayout>

Cartlist_layout - listview的结构

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">
</TextView>

// addtocart_layout

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

<TextView
    android:text="Total :    Rs"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/textView10"
    android:textSize="20sp"
    android:textStyle="normal|bold"
    android:layout_marginTop="16dp"
    android:layout_below="@+id/textView9"
    android:layout_alignStart="@+id/textView9" />

<EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:inputType="number"
    android:ems="4"
    android:id="@+id/editText6"
    android:text="1"
    android:layout_alignBaseline="@+id/textView9"
    android:layout_alignBottom="@+id/textView9"
    android:layout_alignStart="@+id/textView11" />

<TextView
    android:text="0"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/textView11"
    android:textStyle="normal|bold"
    android:textSize="20sp"
    android:layout_alignBaseline="@+id/textView10"
    android:layout_alignBottom="@+id/textView10"
    android:layout_alignParentEnd="true"
    android:layout_marginEnd="142dp" />

<TextView
    android:text="Quantity"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/textView9"
    android:textSize="20sp"
    android:textStyle="normal|bold"
    android:layout_marginTop="36dp"
    android:layout_below="@+id/textView7"
    android:layout_toStartOf="@+id/textView11"
    android:layout_marginEnd="45dp" />

<TextView
    android:text="ItemName"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/textView7"
    android:textStyle="normal|bold"
    android:textSize="20sp"
    android:layout_marginTop="95dp"
    android:layout_alignParentTop="true"
    android:layout_toEndOf="@+id/textView10"
    android:layout_marginStart="12dp" />

</RelativeLayout>

CartDialog - java文件

public class CartDialog extends DialogFragment {
    String item;
    TextView iname,t11;
    EditText qty;
    LayoutInflater inflater;
    View view;
    NumberPicker numberPicker;
    public static int sprice[]={40,50,60,25,30,30,25,25,20,20,20,15,15};
    public String names[]=new String[]{"Item1","Item2","Item3"};
    public ListView l1;
    int i=0;
    List itemName;
    LinearLayout rl;

    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        inflater=getActivity().getLayoutInflater();
        itemName=new ArrayList();
        view=inflater.inflate(R.layout.addtocart_layout,null);
        rl = (LinearLayout)view.inflate(this.getContext(), R.layout.fragment_cart,null);
        //#s1 This code is for some other functionality.  
        iname=(TextView)view.findViewById(R.id.textView7);
        iname.setText(MyMenu.item1);
        int id=Integer.parseInt(MyMenu.childid);
        qty=(EditText)view.findViewById(R.id.editText6);
        t11=(TextView)view.findViewById(R.id.textView11);
            t11.setText(Integer.toString(Integer.parseInt(qty.getText().toString())*sprice[id]));
    qty.addTextChangedListener(
            new TextWatcher() {
                int id=Integer.parseInt(MyMenu.childid);
                @Override
                public void beforeTextChanged(CharSequence s, int start, int count, int after) {

                }

                @Override
                public void onTextChanged(CharSequence s, int start, int before, int count) {

                }

                @Override
                public void afterTextChanged(Editable s) {
                    String qty_value=qty.getText().toString();
                    if(!qty_value.equals(""))
                        t11.setText(Integer.toString(Integer.parseInt(qty_value)*sprice[id]));
                    else
                        t11.setText("");

                }
            }
    );
     #s1 ends here

    AlertDialog.Builder builder=new AlertDialog.Builder(getActivity());
    builder.setView(view).setPositiveButton("Add to Cart", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            onAddToCart();
        }
    }).setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {

        }
    });

    return builder.create();
}
public void onAddToCart(){
//PLAUSIBLE PROBLEM HERE - i think, Something must be wrong here   
    ArrayAdapter<String> adapter1=new ArrayAdapter<String>(this.getContext(),R.layout.cartlist_layout,names);
    l1=(ListView)rl.findViewById(R.id.listview_cart);
    l1.setAdapter(adapter1);
    Toast.makeText(this.getContext(),"Added to Cart:"+l1.getItemAtPosition(0),Toast.LENGTH_SHORT).show();
}
}

Answer 1

当你夸大你的fragment_cart布局时，你没有将它附加到任何东西，这就是为什么你看不到你的结果。

从您显示的图像来看，fragment_cart布局似乎实际上是活动的一部分。

你可以做这样的事情

主要活动

public class MainActivity extends Activity {
    public Fragment mCartFragment;
    //...

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

        mCartFragment = new CartFragment();
        // Attach this fragment to your main activity
    }
}

购物车碎片

public class CartFragment extends Fragment {

    View mView;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater,
                         ViewGroup container, Bundle s) {

        // inflate fragment_cart here
        mView = inflater.inflate(
                R.layout.fragment_cart,
                container,
                false
        );

        return mView;
    }
}

在你的addToCart（）方法中（假设MainActivity负责启动CartDialog）：

public void addToCart(){
    MainActivity mainActivity = (MainActivity)getActivity();
    View fragmentCartView = mainActivity.mCartFragment.getView();
    if(fragmentCartView != null){
        ArrayAdapter<String> adapter1=new ArrayAdapter<String>(this.getContext(),R.layout.cartlist_layout,names);
        l1 = fragmentCartView.findViewById(R.id.listview_cart);
        l1.setAdapter(adapter1);
        Toast.makeText(this.getContext(),"Added to Cart:"+l1.getItemAtPosition(0),Toast.LENGTH_SHORT).show();
    }
}

现在，我不太喜欢这个解决方案，因为你将CartDialog与主要活动相结合，但我并不想过多地改变你的代码。

Answer 2

尝试在您的方法中添加此内容：
adapter1.notifyDataSetChanged（）;

listview项目未显示在android

2 个答案: