Java 微调器中的空指针设置适配器
这是我的代码,其中有一个错误。 我认为每一个都可以,但我不知道哪里有错误 这是我的代码:Java 微调器中的空指针设置适配器,java,android,eclipse,nullpointerexception,spinner,Java,Android,Eclipse,Nullpointerexception,Spinner,这是我的代码,其中有一个错误。 我认为每一个都可以,但我不知道哪里有错误 这是我的代码: public class MainActivity extends Activity implements OnItemSelectedListener{ private EditText promAcum; private EditText credCur; private EditText sem; private EditText num_examenes; private EditText edit
public class MainActivity extends Activity implements OnItemSelectedListener{
private EditText promAcum;
private EditText credCur;
private EditText sem;
private EditText num_examenes;
private EditText editText13;
private EditText editText14;
private EditText editText15;
private EditText editText16;
private EditText editText17;
private EditText editText18;
private EditText editText19;
private EditText editText20;
private EditText editText21;
private Spinner spinner1;
public String valorPromAcum;
public String valorCredCur;
public String valorSem;
public String[] numeroExamenes={"3","4","5","6"};
private final static String TAG_FRAGMENT = "TAG_FRAGMENT";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FragmentManager fm = getFragmentManager();
Fragment fragment = fm.findFragmentById(R.id.fragment_content);
if (fragment == null) {
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.fragment_content, new MainFragment());
ft.commit();
}
promAcum = (EditText) findViewById(R.id.promAcum);
credCur = (EditText) findViewById(R.id.credCur);
sem = (EditText) findViewById(R.id.sem);
editText13 = (EditText)findViewById(R.id.editText13);
editText14 = (EditText)findViewById(R.id.editText14);
editText15 = (EditText)findViewById(R.id.editText15);
editText16 = (EditText)findViewById(R.id.editText16);
editText17 = (EditText)findViewById(R.id.editText17);
editText18 = (EditText)findViewById(R.id.editText18);
editText19 = (EditText)findViewById(R.id.editText19);
editText20 = (EditText)findViewById(R.id.editText20);
editText21 = (EditText)findViewById(R.id.editText21);
spinner1 = (Spinner) findViewById(R.id.spinner1);
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String> (this,android.R.layout.simple_spinner_item,numeroExamenes);
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner1.setAdapter(dataAdapter);
addListenerOnSpinnerItemSelection();
}
public void addListenerOnSpinnerItemSelection(){
spinner1.setOnItemSelectedListener(new OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view,
int position, long id) {
Toast.makeText(MainActivity.this,
"On Button Click : " +
"\n" + String.valueOf(spinner1.getSelectedItem()) ,
Toast.LENGTH_LONG).show();
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
// TODO Auto-generated method stub
}
});}
如果您试图从
活动
中检索视图,欢迎您提供任何建议,但这些建议位于片段
中
getActivity().findViewById(R.id.yourId)无论何时使用findViewById()
方法,都应该使用code>。NullPointerException不是实例化适配器的问题,而是获取微调器的方式的问题
如果片段中存在微调器,则需要指定其上下文
只需将findviewbyd()放在这个.findviewbyd()中,这是您的活动。换句话说,您告诉方法在活动的内容视图中查找视图
如果微调器位于片段的内容视图中,则需要使用
fragment.getActivity().findViewById(R.id.???);
这样findViewById()就知道如何在片段的上下文中找到微调器
希望这有帮助 是post xml名称活动\u main
。如果不是,视图可能属于片段布局。
enter code here09-03 11:25:46.344: E/AndroidRuntime(7841): Caused by: java.lang.NullPointerException
09-03 11:25:46.344: E/AndroidRuntime(7841): at com.jonathanar.promapp.MainActivity.onCreate(MainActivity.java:78)
fragment.getActivity().findViewById(R.id.???);