E / AndroidRuntime:致命错误:主要
在测试我的应用程序时,我在Android Studio-Consol中收到关注错误:
08-21 13:56:28.059 9637-9637/net.dominik.genpush E/AndroidRuntime﹕ FATAL EXCEPTION: mainProcess: net.dominik.genpush, PID: 9637
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{net.dominik.genpush/net.dominik.genpush.settings}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.app.Activity.findViewById(Activity.java:1884)
at net.dominik.genpush.settings.<init>(settings.java:23)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1208)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2101)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
这是一段代码:
public CheckBox checkBox_push; public TextView textView_appby;
public Button button_feedback;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_settings);
checkBox_push = (CheckBox) findViewById(R.id.checkBox_push);
textView_appby = (TextView) findViewById(R.id.textView_appby);
button_feedback = (Button) findViewById(R.id.button_feedback);
}
public void onTextClickAppBy(View x)
{
Intent intent = new Intent();
intent.setAction(Intent.ACTION_VIEW);
intent.addCategory(Intent.CATEGORY_BROWSABLE);
intent.setData(Uri.parse("http://www.dominiktv.net"));
startActivity(intent);
}
//Button Status Speichern
@Override
public void onPause() {
super.onPause();
save(checkBox_push.isChecked());
}
@Override
public void onResume() {
super.onResume();
checkBox_push.setChecked(load());
}
private void save(final boolean isChecked) {
SharedPreferences sharedPreferences = getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putBoolean("check", isChecked);
editor.commit();
}
private boolean load() {
SharedPreferences sharedPreferences = getPreferences(Context.MODE_PRIVATE);
return sharedPreferences.getBoolean("check", true);
}
public void onCheckboxPush(View b)
{
if (checkBox_push.isChecked())
{
//PB
Pushbots.getInstance().setNotifyStatus(true);
//PB E
Toast.makeText(getApplicationContext(), "Push-Benachrichtigungen aktiviert",
Toast.LENGTH_SHORT).show();
}
else
{
//PB
Pushbots.getInstance().setNotifyStatus(false);
//PB E
Toast.makeText(getApplicationContext(), "Push-Benachrichtigungen deaktiviert",
Toast.LENGTH_SHORT).show();
}
}
该应用程序也可以处理该错误,但是在一个应用程序中出现错误并不是很好。我已经用谷歌搜索了很多,但是我的Java技能还远远不够,这是我第一个自行创建的应用
回答:
Caused by: java.lang.NullPointerException
at android.app.Activity.findViewById(Activity.java:1884)
at net.dominik.genpush.settings.
findViewById()
初始化活动settings
对象(可能是成员变量)时,您调用得太早了。您发布的代码未显示该代码。
您只能在onCreate()
以后才调用活动功能。
还要放在findViewById()
之后,setContentView()
以便它实际上可以返回非null的值。
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