Question

我开始使用新的工具栏，但我在MainActivity上获得了NPE。我无法理解为什么我得到它，因为我没有使用setDisplayShowHomeEnabled(boolean)，因为它在错误中引用。你能帮我吗？

MainActivity：

public class MainActivity extends BaseActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setTitle("Title!");
        toolbar.setTitleTextColor(Color.parseColor("#b78c07"));

        db_helper = new DatabaseHelper(this.getApplicationContext());
       (...)


public class BaseActivity extends ActionBarActivity {...}

例外：

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBar.setDisplayShowHomeEnabled(boolean)' on a null object reference
            at com.android.asminhasdespesas.VerActivity.onCreate(VerActivity.java:41)
            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)

layout.XML

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#fdeec1"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context=".MainActivity">


    <android.support.v7.widget.Toolbar
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:id="@+id/toolbar"
        android:layout_alignParentBottom="true"
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:background="@drawable/toolbar_main">
    </android.support.v7.widget.Toolbar>


    <LinearLayout

        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:gravity="center"
        android:layout_gravity="center"
        android:paddingTop="70dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">
(...)

Android：使用工具栏获取空指针异常

0 个答案: