使用單選按鈕更改視圖可見性時的NPE

Question

我試圖通過單擊單選按鈕來更改視圖的可見性並編輯文本，但它不起作用。問題是一個java空指針。我該如何解決它？我證實所有變量都是正確的。

public class MainActivity extends Activity { 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
    } 

    View rad1 = (RadioButton)findViewById(R.id.radio1); 
    View rad2 = (RadioButton)findViewById(R.id.radio2); 



    final View test = findViewById(R.id.ProvencePrefecureView); 
    final EditText test1 = (EditText) findViewById(R.id.ProvencePrefecureEdit); 
    final View test2 = findViewById(R.id.rg); 
    final View test3 = (EditText) findViewById(R.id.Commune_arrondView); 
    final EditText test4 = (EditText) findViewById(R.id.Commune_arrondEdit); 

    public void onRadioButtonClicked(View view) { 
     // Is the button now checked? 
     boolean checked = ((RadioButton) view).isChecked(); 

     // Check which radio button was clicked 
     switch(view.getId()) { 
      case R.id.radio1: 
       if (checked) 
        test.setVisibility(1); 
       test1.setVisibility(1); 
       test3.setVisibility(1); 
       test4.setVisibility(1); 
       break; 
      case R.id.radio2: 
       if (checked) 
        break; 
     } 
    } 
} 

XML：

<TextView 
    android:id="@+id/ProvencePrefecureView" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignLeft="@+id/RegionView" 
    android:layout_below="@+id/RegionEdit" 
    android:layout_marginTop="16dp" 
    style="@style/question" 
    android:visibility="gone" 
    android:text="2. Province ou Préfecture : " 
    /> 

<EditText 
    android:id="@+id/ProvencePrefecureEdit" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:layout_alignLeft="@+id/ProvencePrefecureView" 
    android:layout_below="@+id/ProvencePrefecureView" 
    android:layout_marginTop="6dp" 
    style="@style/reponse" 
    android:visibility="gone" 
    android:ems="10" 
    /> 

<TextView 
    android:id="@+id/Commune_arrondView" 
    android:layout_width="wrap_content" 
    android:visibility="gone" 
    android:layout_height="wrap_content" 
    android:layout_alignRight="@+id/IDENTView" 
    style="@style/question" 
    android:layout_below="@+id/ProvencePrefecureEdit" 
    android:layout_marginTop="16dp" 
    android:text="3. Commune/Arrondissement : " 
    /> 

<EditText 
    android:id="@+id/Commune_arrondEdit" 
    android:layout_width="fill_parent" 
    android:visibility="gone" 
    android:layout_height="wrap_content" 
    android:layout_alignLeft="@+id/NumeroDiscrictEdit" 
    android:layout_below="@+id/Commune_arrondView" 
    android:layout_marginTop="6dp" 
    style="@style/reponse" 
    android:ems="10" 
    /> 

Answer 1

Java中的所有代碼都必須是在一個方法。試試這個：

final View rad1; 
final View rad2; 

final View test; 
final EditText; 
final View test2; 
final View test3; 
final EditText test4; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 

    super.onCreate(savedInstanceState); 

    setContentView(R.layout.activity_main); 

    rad1 = (RadioButton)findViewById(R.id.radio1); 
    rad2 = (RadioButton)findViewById(R.id.radio2); 

    test = findViewById(R.id.ProvencePrefecureView); 
    test1 = (EditText) findViewById(R.id.ProvencePrefecureEdit); 
    test2 = findViewById(R.id.rg); 
    test3 = (EditText) findViewById(R.id.Commune_arrondView); 
    test4 = (EditText) findViewById(R.id.Commune_arrondEdit); 

}