ArrayList只顯示SharedPreferences中的1項

Question

我有3個片段。

1st片段用於顯示Listview。

第二個片段是顯示用戶在第一個片段中點擊的按鈕（添加到購物車）。

第3個片段用於顯示要添加到購物車的產品總數。

我已經加入了不同的產品，很多次，但是，它只能顯示最後一個項目被添加到購物車，其餘的產品並沒有在ListView

display_listview.java

顯示

public class display_listview extends Fragment { 

String[] mobileArray = {"Android","IPhone","WindowsMobile","Blackberry","WebOS","Ubuntu","Windows7","Max OS X"}; 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    // Inflate the layout for this fragment 

    View v=inflater.inflate(R.layout.fragment_display_listview, container, false); 

    ListView listView = (ListView)v.findViewById(R.id.lv); 
    ArrayAdapter adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, mobileArray); 
    listView.setAdapter(adapter); 
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
     @Override 
     public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) { 


      String product_name=adapterView.getItemAtPosition(i).toString(); 

      product_details my_alert=new product_details(); 
      my_alert.show(getActivity().getSupportFragmentManager(),""); 

      Bundle bundle = new Bundle(); 
      bundle.putString("name",product_name); 
      my_alert.setArguments(bundle); 

     } 
    }); 

    Button get_button=(Button)v.findViewById(R.id.cart); 
    get_button.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 

      FragmentManager manager=getActivity().getSupportFragmentManager(); 
      FragmentTransaction transaction=manager.beginTransaction(); 
      my_cart list=new my_cart(); 
      transaction.replace(R.id.top,list); 
      transaction.addToBackStack("wtf"); 
      transaction.commit(); 
     } 
    }); 
    return v; 
} 
} 

show_product.java

public class show_product extends DialogFragment { 

LayoutInflater inflater; 
View v; 
ArrayList<String> products_clicked=new ArrayList<String>(); 

public Dialog onCreateDialog(Bundle savedInstanceState) { 

    inflater=getActivity().getLayoutInflater(); 
    v=inflater.inflate(R.layout.fragment_product_details,null); 

    TextView get_text=(TextView)v.findViewById(R.id.text); 

    Bundle bundle = getArguments(); 
    final String name= bundle.getString("name"); 
    get_text.setText(name); 

    AlertDialog.Builder build=new AlertDialog.Builder(getActivity()); 

    build.setView(v).setPositiveButton("Add to cart", new DialogInterface.OnClickListener() { 

     @Override 
     public void onClick(DialogInterface dialogInterface, int i) { 

      SharedPreferences preferences = getActivity().getSharedPreferences("order_list", Context.MODE_PRIVATE); 
      SharedPreferences.Editor editor=preferences.edit(); 

      products_clicked.add(name); 
      Set<String> set = new HashSet<String>(); 
      set.addAll(products_clicked); 

      editor.putStringSet("yourKey", set); 
      editor.commit(); 

      Toast.makeText(getActivity(),name +" has added to cart.", Toast.LENGTH_LONG).show(); 
     } 
    }); 
    return build.create(); 

} 
} 

my_cart.java

public class my_cart extends Fragment { 


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

    View v=inflater.inflate(R.layout.fragment_my_cart, container, false); 

    SharedPreferences preferences = getActivity().getSharedPreferences("order_list", Context.MODE_PRIVATE); 

    Set<String> set = preferences.getStringSet("yourKey", null); 
    List<String> sample=new ArrayList<String>(set); 
    ArrayAdapter adapter1 = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, sample); 
    ListView listView1 = (ListView)v.findViewById(R.id.listView); 
    listView1.setAdapter(adapter1); 

    return v; 
} 
} 

請參閱截圖

Answer 1

這是因爲product_clicked是一個實例變量，並不會保留以前添加的項目。

修改onClick()方法show_product類是這樣的：

@Override 
public void onClick(DialogInterface dialogInterface, int i) 
{ 
    SharedPreferences preferences = getActivity().getSharedPreferences("order_list", Context.MODE_PRIVATE); 
    SharedPreferences.Editor editor=preferences.edit(); 

    Set<String> set = preferences.getStringSet("yourKey", new HashSet<String>()); 
    set.add(name); 

    editor.putStringSet("yourKey", set); 
    editor.commit(); 

    Toast.makeText(getActivity(),name +" has added to cart.", Toast.LENGTH_LONG).show(); 
} 

正如你可以看到，我們獲取先前保存在SharedPreferences設置，添加新項目，再存放起來。