在actionBar.setHomeButtonEnabled(false)附近获得空指针异常,我还实现了查看分页和选项卡。
我还没有定义@android:style/Theme.Black。清单文件中的NoTitleBar。当我不实现TabView和viewpager并通过一个正常的活动,然后应用程序的工作,但当我尝试实现TabView和viewpager我得到空指针异常。 谁能指出我可能犯的错误?private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
// Tab titles
private String[] tabs = { "Merchants", "Personal Payee" };
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_screen_tab_layout_bp);
//Initilization
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
//Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
@Override
public void onTabSelected(Tab tab, android.app.FragmentTransaction ft) {
// TODO Auto-generated method stub
viewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(Tab tab, android.app.FragmentTransaction ft) {
// TODO Auto-generated method stub
}
@Override
public void onTabReselected(Tab tab, android.app.FragmentTransaction ft) {
// TODO Auto-generated method stub
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu); //inflate our menu
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.item_refresh) {
Intent i = new Intent(MainScreenTab.this,ListMerchantType.class);
startActivity(i);
return true;
}
else if (id == R.id.item_save) {
Intent i = new Intent(MainScreenTab.this,ListPayee.class);
startActivity(i);
return true;
}
return super.onOptionsItemSelected(item);
}
ActionBarCompat包含一个Activity类,它包含所有的Activity类应该扩展:ActionBarActivity。这个类本身扩展从FragmentActivity,所以你可以继续使用碎片在你的应用程序。没有ActionBarCompat Fragment类需要扩展,所以应该继续使用android.support.v4。Fragment作为Fragment的基类。
你的信息在这里:
http://android - developers.blogspot.in/2013/08/actionbarcompat -和- io - 2013 -应用- source.html
这就是为什么你在actionBar
元素上得到NPE的原因。所以你应该这样写:
public class YourActivity extends ActionBarActivity implements TabListener {