我是Android开发的初学者,我想配置硬件按钮以返回上一个片段,片段标题也应根据当前片段进行更改, 这是我的主要活动来源:
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity implements FragmentDrawer.FragmentDrawerListener {
private static String TAG = MainActivity.class.getSimpleName();
private Toolbar mToolbar;
private FragmentDrawer drawerFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mToolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(mToolbar);
getSupportActionBar().setDisplayShowHomeEnabled(true);
drawerFragment = (FragmentDrawer)
getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), mToolbar);
drawerFragment.setDrawerListener(this);
// display the first navigation drawer view on app launch
displayView(0);
}
@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;
}
if(id == R.id.action_search){
Toast.makeText(getApplicationContext(), "Search action is selected!", Toast.LENGTH_SHORT).show();
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onDrawerItemSelected(View view, int position) {
displayView(position);
}
private void displayView(int position) {
Fragment fragment = null;
String title = getString(R.string.app_name);
switch (position) {
case 0:
fragment = new HomeFragment();
title = getString(R.string.title_home);
break;
case 1:
fragment = new MicrosoftDskFragment();
title = "Microsoft Dsk";
break;
case 2:
fragment = new GoogleDskFragment();
title = "Google Dsk";
break;
case 3:
fragment = new AppleDskFragment();
title = "Apple Dsk";
break;
case 4:
fragment = new OthersDskFragment();
title = "Others Dsk";
break;
case 5:
fragment = new AboutUSFragment();
title = "About US";
break;
default:
break;
}
if (fragment != null) {
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.container_body, fragment);
fragmentTransaction.addToBackStack(null).commit();
// set the toolbar title
getSupportActionBar().setTitle(title);
}
}
}
请帮我解决这个问题。
答案 0 :(得分:2)
您正在将该交易添加到后台堆栈中,因此您需要的所有内容应该是:
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.popBackstack(null, 0);
您也可以考虑为每个片段添加一个id,并在调用
时传递它fragmentTransaction.addToBackStack(null).commit();
而不是null。这样,您就可以这样做:
fragmentTransaction.addToBackStack(myFragmentId).commit();
//Later on...
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.popBackstack(myFragmentId, 0);
回到特定片段,而不仅仅是最后一片: - )
答案 1 :(得分:0)
每次添加片段时,只需在提交前添加addToBackStack()方法,然后在您的活动中按下后再尝试此
public void onBackPressed() {
int count = getSupportFragmentManager().getBackStackEntryCount();
if (count == 1) {
goToExitApplication(
getResources().getString(R.string.close_app), true);
} else {
String title = getSupportFragmentManager().getBackStackEntryAt(count - 2).getName();
getSupportFragmentManager().popBackStack();
getSupportActionBar().setTitle(title);
}
}
答案 2 :(得分:0)
我在我的代码中使用了这个:
@Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 0 ){
getSupportFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
推动我使用的碎片:
MyFragment_Items myf = new MyFragment_Items();
transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.container_layout, myf);
transaction.addToBackStack(null);
transaction.commit();
我把片段推到这里然后把它弹回到背景上。
答案 3 :(得分:0)
它肯定会为你工作如果当前片段的后栈上有任何片段,popBackStackImmediate()可以工作..
Gson gson = new GsonBuilder()
.addDeserializationExclusionStrategy(new GsonDeserializeExclusion())
.create();