Question

我正在使用此代码来实现自定义操作栏，但应用程序崩溃了。我正在使用布局充气器来返回自定义布局的视图，然后将其应用到操作栏。

这是custom.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
android:layout_height="70dp"
android:background="#00897B" >


<Button
    android:layout_width="190dp"
    android:layout_height="wrap_content"
    android:text="Register an event"
    android:textColor="#ffffff"
    android:background="#4db6ac"
    android:id="@+id/button1"
    android:layout_centerVertical="true"
    android:layout_alignParentStart="true" />

<ImageView
    android:layout_width="40dp"
    android:layout_height="wrap_content"
    android:id="@+id/imageView1"
    android:src="@drawable/refr"
    android:layout_alignParentTop="true"
    android:layout_alignParentEnd="true"
    android:layout_marginEnd="32dp" />
</RelativeLayout>

这是MainActivity.java

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ActionBar actionBar=getActionBar();
    LayoutInflater l=(LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
    View v1=l.inflate(R.layout.custom,null);
    actionBar.setCustomView(v1);

}


}

以下是应用崩溃时的错误：

 Process: com.khurana.nikhil.navigationdrawer, PID: 2255
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.khurana.nikhil.navigationdrawer/com.khurana.nikhil.navigationdrawer.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setCustomView(android.view.View)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
        at android.app.ActivityThread.access$800(ActivityThread.java:151)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5257)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setCustomView(android.view.View)' on a null object reference
        at com.khurana.nikhil.navigationdrawer.MainActivity.onCreate(MainActivity.java:24)
        at android.app.Activity.performCreate(Activity.java:5990)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)

Answer 1

你输了

super.onCreate(savedInstanceState);
setContentView(R.layout.someView);

尝试使用getSupportActionBar（）而不是getActionBar（）。

如果这没有帮助，请尝试更改样式中的应用主题，也许您使用NoActionBar主题

<强>更新

    public class MainActivity extends AppCompatActivity {

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            ActionBar actionBar = getSupportActionBar();
            View v1 = getLayoutInflater().inflate(R.layout.custom, null);
            actionBar.setCustomView(v1);
        }
    }

Answer 2

您如何尝试将主题设置为支持ActionBar的主题，例如Theme.Holo.Light?

此外，在您的活动中，您可以尝试getActionBar().show();

Answer 3

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;

public class Principale extends Activity {


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.ecran_d_acceuil);


}
public boolean onCreateOptionMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.principale, menu);
    return true;
}
 }

试试这个。

Android自定义栏无法显示

3 个答案: