Question

我正在尝试制作此错误。

当我点击一个按钮并执行“showData（）”函数时; 我想做这个功能的原因是因为我想在什么时候更改片段我单击此按钮并将“传递参数”传递给新片段。所以它将继续执行函数“passData（）”;

但是在“editTextNAME.setText（restaurant.name）”之后它会得到NullPointerException;这条线。

showData（）

    public void showData(View view){
    RestaurantRepo repo = new RestaurantRepo(this);
    ArrayList<HashMap<String, String>> restaurantList =  repo.getRestaurantList();
    if ( restaurantList.size()!=0 ) {
        ListView lv = (ListView) findViewById(R.id.list);
        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
                restaurantID = (TextView) view.findViewById(R.id.restaurantID);
                String idRestaurant = restaurantID.getText().toString();

                Bundle data = new Bundle();
                data.putString("restaurantID", idRestaurant); // argument

                Fragment fraUorD = null;
                fraUorD = new EditFragment_Fix_UorD();

                if ( null != fraUorD ) {
                    android.app.FragmentManager fragementManager = getFragmentManager();
                    android.app.FragmentTransaction transaction = fragementManager.beginTransaction();
                    transaction.replace(R.id.content_frame, fraUorD);
                    transaction.addToBackStack(null);
                    transaction.commit();
                    passData(data); // when transaction done , execute passData() -> i want to pass argument when the new fragment come out
                }

            }
        });

        ListAdapter adapter = new SimpleAdapter( MainActivity.this,restaurantList, R.layout.edit_fragment_fix_view,
                new String[] { "id","name","type","price","phone","addr"},
                new int[] {R.id.restaurantID, R.id.restaurantNAME,R.id.restaurantTYPE,
                        R.id.restaurantPRICE,R.id.restaurantPHONE,R.id.restaurantADDR});
        lv.setAdapter(adapter);
    }

    else
        Toast.makeText(this,"No restaurant!",Toast.LENGTH_SHORT).show(); // no data

passData（）

   public void passData(Bundle data){

    int a = Integer.parseInt( data.getString("restaurantID", "")) ; // get it 

    Toast.makeText(this, ""+a,Toast.LENGTH_SHORT).show();

    editTextNAME = (EditText) findViewById(R.id.editTextUpdateName);
    editTextTYPE = (EditText) findViewById(R.id.editTextUpdateType);
    editTextPRICE = (EditText) findViewById(R.id.editTextUpdatePrice);
    editTextPHONE = (EditText) findViewById(R.id.editTextUpdatePhone);
    editTextADDR = (EditText) findViewById(R.id.editTextUpdateAddr);

    RestaurantRepo repo = new RestaurantRepo(this);
    Restaurant restaurant = new Restaurant();
    restaurant = repo.getRestaurantById(a);

    // Everything is ok, but when executing codes below here will get errors 
    // ↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓

    editTextNAME.setText(restaurant.name);
    editTextTYPE.setText(String.valueOf(restaurant.type));
    editTextPRICE.setText(String.valueOf(restaurant.price));
    editTextPHONE.setText(restaurant.phone);
    editTextADDR.setText(restaurant.addr);
}

Logcat：

java.lang.NullPointerException：尝试在空对象引用上调用虚方法'void android.widget.EditText.setText（java.lang.CharSequence）' at com.example.user.foody.MainActivity $ override.passData（MainActivity.java:284） at com.example.user.foody.MainActivity $ override.access $ dispatch（MainActivity.java）在com.example.user.foody.MainActivity.passData（MainActivity.java:0）在com.example.user.foody.MainActivity $ 2 $ override.onItemClick（MainActivity.java:244） at com.example.user.foody.MainActivity $ 2 $ override.access $ dispatch（MainActivity.java）在com.example.user.foody.MainActivity $ 2.onItemClick（MainActivity.java:0）

Answer 1

问题是在onViewCreated之前你无法在片段上找到view byId。

我建议阅读这篇关于通过片段传递数据的帖子。 http://gunhansancar.com/best-practice-to-instantiate-fragments-with-arguments-in-android/

重要的一块：

public static MyFragment newInstance(...)

单击“按钮”将参数从片段传递到另一个片段

1 个答案: