我知道以前曾经问过类似的问题，但我似乎无法找到我正在寻找的东西。我的问题是我的后退按钮当前正在退出应用程序。我要做的是让它导航到前一个片段。就像你打开fragment1 - ＆gt; fragment2，然后按后退按钮，它会带你回到fragment1。
我目前的代码是这样的。
public class MainActivity extends FragmentActivity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
private CharSequence mDrawerTitle;
private CharSequence mTitle;
private String[] mPageTitles;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTitle = mDrawerTitle = getTitle();
mPageTitles = getResources().getStringArray(R.array.menu_array);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
// set a custom shadow that overlays the main content when the drawer
// opens
mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow,
GravityCompat.START);
// set up the drawer's list view with items and click listener
mDrawerList.setAdapter(new ArrayAdapter<String>(this,
R.layout.drawer_list_item, mPageTitles));
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
// enable ActionBar app icon to behave as action to toggle nav drawer
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
// ActionBarDrawerToggle ties together the the proper interactions
// between the sliding drawer and the action bar app icon
mDrawerToggle = new ActionBarDrawerToggle(this, /* host Activity */
mDrawerLayout, /* DrawerLayout object */
R.drawable.ic_drawer, /* nav drawer image to replace 'Up' caret */
R.string.drawer_open, /* "open drawer" description for accessibility */
R.string.drawer_close /* "close drawer" description for accessibility */
)
{
public void onDrawerClosed(View view) {
getActionBar().setTitle(mTitle);
invalidateOptionsMenu(); // creates call to
// onPrepareOptionsMenu()
}
public void onDrawerOpened(View drawerView) {
getActionBar().setTitle(mDrawerTitle);
invalidateOptionsMenu(); // creates call to
// onPrepareOptionsMenu()
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
// Sets the firstpage if no state is found
if (savedInstanceState == null) {
selectItem(0);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return super.onCreateOptionsMenu(menu);
}
/* Called whenever we call invalidateOptionsMenu() */
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
// If the nav drawer is open, hide action items related to the content
// view
return super.onPrepareOptionsMenu(menu);
}
// Toogles the drawer menu
@Override
public boolean onOptionsItemSelected(MenuItem item) {
return mDrawerToggle.onOptionsItemSelected(item);
}
/* The click listner for ListView in the navigation drawer */
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) {
// update the main content by replacing fragments
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
switch (position) {
case 0:
KontaktInfoFragment kontakt = new KontaktInfoFragment();
fragmentTransaction.replace(R.id.content_frame, kontakt);
fragmentTransaction.addToBackStack("Replace");
fragmentTransaction.commit();
break;
case 1:
OmOssFragment omoss = new OmOssFragment();
fragmentTransaction.replace(R.id.content_frame, omoss);
fragmentTransaction.addToBackStack("Replace");
fragmentTransaction.commit();
break;
case 2:
MainScreenActivity mainscreen = new MainScreenActivity();
fragmentTransaction.replace(R.id.content_frame, mainscreen);
fragmentTransaction.addToBackStack("Replace");
fragmentTransaction.commit();
break;
case 3:
LoginFragment login = new LoginFragment();
fragmentTransaction.replace(R.id.content_frame, login);
fragmentTransaction.addToBackStack("Replace");
fragmentTransaction.commit();
break;
case 4:
ContactFormFragment form = new ContactFormFragment();
fragmentTransaction.replace(R.id.content_frame, form);
fragmentTransaction.addToBackStack("Replace");
fragmentTransaction.commit();
break;
}
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
setTitle(mPageTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
}
@Override
public void setTitle(CharSequence title) {
mTitle = title;
getActionBar().setTitle(mTitle);
}
}
答案 0 :(得分：0)
当您按下碎片内部的后退按钮onBackPressed（）时，如果您声明了活动，则会调用您的活动方法。因此，导航抽屉内的碎片处理后退按钮可以是这样的方式..
MainActvity
public static boolean isMainActivityShown ;
public static boolean isFragment1Shown=false ;
public static boolean isFragment2Shown=false ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
isMainActivityShown=true //inside onCreate method put isMainActivityShown true
.
.
.
}
Fragment currentFragment = new Fragment1();
isMainActivityShown=false; //when moving to fragment1
isFragment1Shown=true;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
.commit();
@Override
public void onBackPressed() {
if(isMainActivityShown)
{
finish();
}
else if(isFragment1Shown)
{
//write the code to handle back button when you are in Fragment1
}
else if(isFragment2Shown)
{ //When you are in Fragment 2 pressing back button will move to fragment1
Fragment currentFragment = new Fragment1();
isFragment2Shown=false;
isFragment1Shown=true;
FragmentManager frgManager;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
.commit();
}
}
片段1
Fragment currentFragment = new Fragment2();
MainActivity.isFragment1Shown=false;
MainActivity.isFragment2Shown=true;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
.commit();