5
我有代碼：findViewById返回null
public class HelloWorld extends Activity {
private Button buttonOk;
private Button buttonCancel;
private OnClickListener buttonOkListener = new OnClickListener() {
public void onClick(View v){
EditText editText = (EditText)findViewById(R.id.input);
CharSequence textFromInput = (CharSequence) editText.getText();
Context context = getApplicationContext();
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context,textFromInput,duration);
toast.show();
}
};
private OnClickListener buttonCancelListener = new OnClickListener() {
public void onClick(View v){
EditText editText = (EditText)findViewById(R.id.input);
CharSequence textFromInput = (CharSequence) editText.getText();
Context context = getApplicationContext();
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context,textFromInput,duration);
toast.show();
}
};
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
// ToDo add your GUI initialization code here
setContentView(R.layout.main);
buttonOk = (Button)findViewById(R.id.buttonOk);
buttonCancel = (Button)findViewById(R.id.buttonCancel);
buttonOk.setOnClickListener(buttonOkListener);
buttonCancel.setOnClickListener(buttonCancelListener);
}
}
和佈局文件：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
android:id="@+id/label"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Wpisz swoje imię:"/>
<EditText
android:id="@+id/input"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="@android:drawable/editbox_background"
android:layout_below="@id/label"/>
<Button
android:id="@+id/buttonOk"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/input"
android:layout_alignParentRight="true"
android:layout_marginLeft="10dip"
android:text="OK" />
<Button
android:id="@+id/buttonCancel"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toLeftOf="@id/buttonOk"
android:layout_alignTop="@id/buttonOk"
android:text="Anuluj" />
</RelativeLayout>
線與buttonCancel.setOnClickListener（buttonCancelListener）;拋出異常，因爲buttonCancel爲null。我做錯了什麼？
我面臨同樣的問題。即使代碼中的所有內容看起來都正確，但FindViewById將返回null與其中一個按鈕。 – castle1971 2011-10-26 07:48:05