Android 按“后退”按钮将MainActivity分割并返回到MainActivity
我有一个Mainactivity,其中包含一个布局,它是4个子布局的父级。单击子布局,我将看到一个新的片段替换主布局。但按下“后退”按钮后,我无法返回主活动 MainActivity.javaAndroid 按“后退”按钮将MainActivity分割并返回到MainActivity,android,android-fragments,Android,Android Fragments,我有一个Mainactivity,其中包含一个布局,它是4个子布局的父级。单击子布局,我将看到一个新的片段替换主布局。但按下“后退”按钮后,我无法返回主活动 MainActivity.java public class MainActivity extends AppCompatActivity { RelativeLayout aboutUs; @Override protected void onCreate(Bundle savedInstanceState) {
public class MainActivity extends AppCompatActivity {
RelativeLayout aboutUs;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
aboutUs = (RelativeLayout) findViewById(R.id.aboutUs);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
//click methods goes here
public void clickAboutUs(View view){
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
FragmentAboutUs fragmentAboutUs = new FragmentAboutUs();
fragmentTransaction.replace(R.id.fragment_container,fragmentAboutUs);
fragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
FragmentAboutUs.java
public class FragmentAboutUs extends Fragment
{
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.about_us, container,false);
return view;
}
}
如何在按了fragment中的“后退”按钮后再次返回主页。像这样尝试
public boolean popFragment() {
boolean isPop = false;
Fragment currentFragment = getSupportFragmentManager()
.findFragmentById(R.id.flContent);
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
isPop = true;
getSupportFragmentManager().popBackStackImmediate();
}
return isPop;
}
@Override
public void onBackPressed() {
if (!popFragment()) {
finish();
}
}
public void replaceFragment(Fragment fragment, boolean addToBackStack) {
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
if (addToBackStack) {
transaction.addToBackStack(null);
} else {
getSupportFragmentManager().popBackStack(null,
FragmentManager.POP_BACK_STACK_INCLUSIVE);
}
transaction.replace(R.id.fragment_container, fragment);
transaction.commit();
getSupportFragmentManager().executePendingTransactions();
}
在父活动中添加上述方法
和使用一样
FragmentAboutUs fragmentAboutUs = new FragmentAboutUs();
replaceFragment(fragmentAboutUs , true);
您可以覆盖MainActivity的onBackPressed
@Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 1) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
如果您有一个活动和四个片段,请在
main活动中设置onBackPressed()
@Override
public void onBackPressed()
{
super.onBackPressed();
finish();
}
碎片:
@Override
public void onResume() {
super.onResume();
new PlayListFragment();
getView().setFocusableInTouchMode(true);
getView().requestFocus();
getView().setOnKeyListener(new View.OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK){
if(getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
}
return true;
}
return false;
}
});
}
以下是如何在Xamarin中执行此操作:
加载片段(我为此编写了helper方法,但这不是必需的):
后退按钮(在main活动中)
:
IsNavDrawerRopen
方法:
bool isNavDrawerOpen()
{
return drawerLayout != null && drawerLayout.IsDrawerOpen(Android.Support.V4.View.GravityCompat.Start);
}
仍然不工作,我没有使用android.support.v4.fragment,而是使用take fragment.appsorry尝试replaceframent(fragmentAboutUs,true)代码>这又是一个问题。如何将数据发送到下一个片段,以便在具有不同值的片段上重用。有什么想法吗?使用bundle并将数据发送到frugmentAboutus.setArguments(yourbundle)这样的frugments。这其中的R.id.flContent是什么?在fragmentTransaction.commit()之前添加这一行;“fragmentTransaction.addToBackStack(null);”
public override void OnBackPressed()
{
if (isNavDrawerOpen()) drawerLayout.CloseDrawers();
else
{
var backStackEntryCount = FragmentManager.BackStackEntryCount;
if (backStackEntryCount == 1) Finish();
else if (backStackEntryCount > 1) FragmentManager.PopBackStack();
else base.OnBackPressed();
}
}
bool isNavDrawerOpen()
{
return drawerLayout != null && drawerLayout.IsDrawerOpen(Android.Support.V4.View.GravityCompat.Start);
}