Android getActionBar与getSupportActionBar? [英] Android getActionBar vs getSupportActionBar?

问题描述

这是我的代码:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB){

    //android.support.v7.app.ActionBar actionBar = getSupportActionBar();
    //actionBar.setTitle("Android");

    ActionBar actionBar = getActionBar();
    actionBar.setTitle("Droid");
}

使用getSupportActionBar()时，我的应用程序可以在kitkat和其他新版本上正常运行，但是使用getActionBar会导致错误.

While using the getSupportActionBar() my app runs just fine with kitkat and other new versions but using getActionBar results into an error.

这是错误:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.hide()' on a null object reference
            at com.github.domain.geoquiz.QuizActivity.onCreate(QuizActivity.java:57)
            at android.app.Activity.performCreate(Activity.java:5933)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372

为什么?从android文档:

Why? From android documentations :

警告:请确保您导入了ActionBar类(以及相关的API) 从适当的程序包中:

Caution: Be certain you import the ActionBar class (and related APIs) from the appropriate package:

如果支持的API级别低于11: 导入android.support.v7.app.ActionBar

If supporting API levels lower than 11: import android.support.v7.app.ActionBar

如果仅支持API级别 11或更高版本:导入android.app.ActionBar

If supporting only API level 11 and higher: import android.app.ActionBar

现在为什么这个应用程序崩溃了?

Now why this app is crashing?

推荐答案

如果您使用的是AppCompat，则无论您的应用运行的是哪个Android版本，都必须调用getSupportActionBar().

If you are using AppCompat you always have to call getSupportActionBar() no matter which Android Version your App is running.

您定位到哪个Android版本?

Which Android versions do you target?

我建议您使用新的工具栏代替ActionBar ，因为它使用起来更灵活.

I would advise you to use the new Toolbar instead of ActionBar, because it's way more flexible to use.

这篇关于Android getActionBar与getSupportActionBar?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！