我的应用程序崩溃在运行kitkat(api 19)的设备上,我尝试使用LG g3和nexus 7 2013因为nullPointer预期.
我发现当我执行getActionBar()时它返回null并且我无法修复它.
我使用appcompat主题21和运行棒棒糖的设备的材料主题,在他们的应用程序工作正常.
MainActivity.java:
package com.sqvat.betterpowermat;
import android.app.ActionBar;
import android.app.Activity;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class MainActivity extends Activity {
private ActionBar actionBar;
private String[] categories;
private DrawerLayout drawerLayout;
private ListView drawerList;
private ActionBarDrawerToggle drawerToggle;
private String drawerClose;
private String drawerOpen;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
actionBar = getActionBar();
//Nav Drawer
categories = getResources().getStringArray(R.array.categories);
drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
drawerList = (ListView) findViewById(R.id.left_drawer);
drawerList.setAdapter(new ArrayAdapter<String>(this,
R.layout.nav_drawer_li, R.id.drawer_li_textview, categories));
drawerList.setOnItemClickListener(new DrawerItemClickListener());
drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
drawerToggle = new ActionBarDrawerToggle(this, drawerLayout, R.drawable.ic_drawer, R.string.drawerOpen, R.string.drawerClose) {
/** Called when a drawer has settled in a completely closed state. */
public void onDrawerClosed(View view) {
super.onDrawerClosed(view);
}
/** Called when a drawer has settled in a completely open state. */
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
}
};
// Set the drawer toggle as the DrawerListener
drawerLayout.setDrawerListener(drawerToggle);
actionBar.setDisplayHomeAsUpEnabled(true);
actionBar.setHomeButtonEnabled(true);
selectItem(0);
}
private class DrawerItemClickListener implements ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView parent, View view, int position, long id) {
selectItem(position);
}
}
private void selectItem(int position) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
switch (position){
case 0:
fragmentTransaction.replace(R.id.content_frame, new HomeFragment());
actionBar.setTitle("Home");
break;
case 1:
fragmentTransaction.replace(R.id.content_frame, new LocationsFragment());
actionBar.setTitle("Locations");
break;
case 2:
fragmentTransaction.replace(R.id.content_frame, new StoreFragment());
actionBar.setTitle("Store");
break;
case 3:
fragmentTransaction.replace(R.id.content_frame, new MoreFragment());
actionBar.setTitle("More");
break;
}
fragmentTransaction.commit();
drawerList.setItemChecked(position, true);
drawerLayout.closeDrawer(drawerList);
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
drawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
drawerToggle.onConfigurationChanged(newConfig);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Pass the event to ActionBarDrawerToggle, if it returns
// true, then it has handled the app icon touch event
if (drawerToggle.onOptionsItemSelected(item)) {
return true;
}
// Handle your other action bar items...
return super.onOptionsItemSelected(item);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
我的appcompat样式(values / styles.xml):
<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">@color/colorPrimary</item>
<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
</style>
<color name="colorPrimary">#4CAF50</color>
<color name="colorPrimaryDark">#43A047</color>
我的android棒棒糖样式(values-v21 / styles.xml):
<style name="AppTheme" parent="android:Theme.Material.Light.DarkActionBar">
<item name="android:colorPrimary">@color/colorPrimary</item>
<item name="android:colorPrimaryDark">@color/colorPrimaryDark</item>
</style>
解决方法:
如果要在支持库上使用ActionBar,则必须扩展ActionBarActivity类而不是Activity,并使用getSupportActionBar()代替getActionBar()来获取ActionBar.