通过后退按钮从子片段导航回到父活动

Question

I have a main activity and 2 fragments. In my main activity I have navigation drawer that navigates through the fragments. I handle the back button pressed like this:

@Override
public void onBackPressed() {
    if (getFragmentManager().getBackStackEntryCount() > 0) {
        getFragmentManager().popBackStackImmediate();
    } else {
        super.onBackPressed();
    }
}

After navigating between the two fragments, when I hit the back button, I get last fragment from backstack. However, navigating from fragment to another fragment should not be possible.

More Clarity:

I have one Activity (with a navigation drawer) and 2 Fragments. From the navigation drawer I can go to both fragments as many times as I want. But when I hit the back button, I want always to go back to the main_activity.xml .

Answer 1

When you navigate through Activities, the best way is to use Intent s like this (if I understood your question):

Intent intent = new Intent(this, MainActivity.class);
startActivity(intent);

Answer 2

**OnCreate() :-**


public boolean onKeyDown(int keyCode, KeyEvent event)
 {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            Intent returnIntent = new Intent();
            setResult(RESULT_CANCELED, returnIntent);
            this.finish();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

ActionBar mActionBar = getActionBar();
        mActionBar.setDisplayShowHomeEnabled(false);
        mActionBar.setDisplayShowTitleEnabled(false);

LayoutInflater mInflater = LayoutInflater.from(this);

View mCustomView = mInflater.inflate(R.layout.actionbar_category_feed_list, null);

        RelativeLayout rrBack = (RelativeLayout) mCustomView.findViewById(R.id.rr_back);
        TextView title = (TextView) mCustomView.findViewById(R.id.txt_title);
        title.setText("");
        title.setTypeface(typeFaceMedium);
        rrBack.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                mTracker.send(new HitBuilders.EventBuilder().setCategory("" + userUsername).setAction("On Search Feed Screen").setLabel("Pressed Back Button").build());
                Intent returnIntent = new Intent();
                setResult(RESULT_CANCELED, returnIntent);
                finish();
            }
        });
        mActionBar.setCustomView(mCustomView);
        mActionBar.setDisplayShowCustomEnabled(true);

**actionbar_category_feed_list.xml**

?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="50dp"
    android:background="@android:color/white" >

    <RelativeLayout
        android:id="@+id/rr_back"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_alignParentLeft="true"
        android:layout_centerVertical="true" >

        <ImageView
            android:id="@+id/img_logo"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:focusable="false"
            android:src="@drawable/back_red" />
    </RelativeLayout>

    <com.converza.library.CustomTextView
        android:id="@+id/txt_title"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_centerVertical="true"
        android:layout_toRightOf="@+id/rr_back"
        android:gravity="center_vertical"
        android:paddingLeft="8dp"
        android:text="@string/app_name" />

</RelativeLayout>



**At last in your fragment Activity use a OnactivityResult() for get a Returnintent from Activity.**

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == Const.FEEDDETAIL && resultCode == Activity.RESULT_OK) {
            Log.e(tag, "DatashBoard Const.FEEDDETAIL RESULT_OK");
        } else if (requestCode == Const.FEEDDETAIL && resultCode == Activity.RESULT_CANCELED) {
            Log.e(tag, "DatashBoard Const.FEEDDETAIL RESULT_CANCELED");
        }
    }

Answer 3

You have to find the fragment by tag and check if it is null or not, if it is null then replace that fragment or show the fragment again if fragment is hidden.

    @Override
    public void onBackPressed() {
             Fragment fr = getSupportFragmentManager()
                .findFragmentByTag("Fragment_Tag");

        if (fr == null) {
            getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.container,
                        new Main_Fragment(), "Fragment_Tag").commit();
        } else {
            finish();
        }
}