我想獲得一個ToggleButton的工作,但我有幾個問題。 1.它似乎恢復到默認值,當它被點擊,我導航到另一個屏幕。 2.我嘗試使用SharedPreferences將其isChecked()值傳遞給另一個活動,現在它崩潰。單擊togglebutton時的Nullpointerexception
<ToggleButton
android:id="@+id/togBTN"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/homeBtn"
android:layout_centerHorizontal="true"
android:layout_marginTop="106dp"
android:text="Voice Alerts"
android:textOff="OFF"
android:textOn="ON" />
上述代碼位於我的xml文件中。 下面的代碼是它的onClickListener代碼。
case R.id.togBTN:
SharedPreferences.Editor editor = preferences.edit();
editor.putBoolean("tgpref", tg.isChecked()); // value to store
editor.commit();
break;
}
而這段代碼是我嘗試檢索值
SharedPreferences preferences = getPreferences(MODE_PRIVATE);
boolean tgpref = preferences.getBoolean("tgpref", true); //default is true
if (tgpref = true) //if (tgpref) may be enough, not sure
{
speakValue = true;
}
else
{
speakValue = false;
}
這是我得到的Logcat
:
02-21 14:49:09.587: W/dalvikvm(483): threadid=1: thread exiting with uncaught exception (group=0x40015560)
02-21 14:49:09.597: E/AndroidRuntime(483): FATAL EXCEPTION: main
02-21 14:49:09.597: E/AndroidRuntime(483): java.lang.NullPointerException
02-21 14:49:09.597: E/AndroidRuntime(483): at ohalleran.stephanie.Traffic.SettingsActivity.onClick(SettingsActivity.java:45)
02-21 14:49:09.597: E/AndroidRuntime(483): at android.view.View.performClick(View.java:2485)
02-21 14:49:09.597: E/AndroidRuntime(483): at android.widget.CompoundButton.performClick(CompoundButton.java:99)
02-21 14:49:09.597: E/AndroidRuntime(483): at android.view.View$PerformClick.run(View.java:9080)
02-21 14:49:09.597: E/AndroidRuntime(483): at android.os.Handler.handleCallback(Handler.java:587)
02-21 14:49:09.597: E/AndroidRuntime(483): at android.os.Handler.dispatchMessage(Handler.java:92)
02-21 14:49:09.597: E/AndroidRuntime(483): at android.os.Looper.loop(Looper.java:130)
02-21 14:49:09.597: E/AndroidRuntime(483): at android.app.ActivityThread.main(ActivityThread.java:3683)
02-21 14:49:09.597: E/AndroidRuntime(483): at java.lang.reflect.Method.invokeNative(Native Method)
02-21 14:49:09.597: E/AndroidRuntime(483): at java.lang.reflect.Method.invoke(Method.java:507)
02-21 14:49:09.597: E/AndroidRuntime(483): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-21 14:49:09.597: E/AndroidRuntime(483): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-21 14:49:09.597: E/AndroidRuntime(483): at dalvik.system.NativeStart.main(Native Method)
會很感激一些幫助與此有關。
我通常使用OnCheckedChangeListener切換按鈕:http://developer.android.com/reference/android/widget/CompoundButton.OnCheckedChangeListener.html – AJcodez 2012-02-21 17:16:32