CoderzHeaven

June 5, 2013

How to hide and show a Fragment with animation in Android? and How to retain a state in a Fragment in Android?

Hello everyone

This posts helps you to hide and show a fragment with animation (without XML files animation). And also it shows how to retain a saved state(for eg: a value in a textview).

A little about Fragments
A Fragments is an independent component which can be connected to an activity. A Fragment typically defines a part of a user interface but it is possible to define headless Fragments, i.e. without user interface.

Fragments can be dynamically or statically added to a layout. A Fragment encapsulate functionality so that it is easier to reuse within activity and layouts.

A Fragment component runs in the context of an activity but it has its own lifecycle and their own user interface.

Fragment show or hide

Fragment show or hide

This is the layout that holds two fragments.
You can click on the download link to download the code.

fragment_hide_show.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    android:layout_width="match_parent" android:layout_height="match_parent">

    <TextView android:layout_width="match_parent" android:layout_height="wrap_content"
        android:gravity="center_vertical|center_horizontal"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Demonstration of hiding and showing fragments." />

    <LinearLayout android:orientation="horizontal" android:padding="4dip"
        android:gravity="center_vertical" android:layout_weight="1"
        android:layout_width="match_parent" android:layout_height="wrap_content">

        <Button android:id="@+id/frag1hide"
            android:layout_width="wrap_content" android:layout_height="wrap_content"
            android:text="Hide" />

        <fragment android:name="com.example.fragmentshowingandhiding.FragmentHideShow$FirstFragment"
                android:id="@+id/fragment1" android:layout_weight="1"
                android:layout_width="0px" android:layout_height="wrap_content" />

    </LinearLayout>

    <LinearLayout android:orientation="horizontal" android:padding="4dip"
        android:gravity="center_vertical" android:layout_weight="1"
        android:layout_width="match_parent" android:layout_height="wrap_content">

        <Button android:id="@+id/frag2hide"
            android:layout_width="wrap_content" android:layout_height="wrap_content"
            android:text="Hide" />

        <fragment android:name="com.example.fragmentshowingandhiding.FragmentHideShow$SecondFragment"
                android:id="@+id/fragment2" android:layout_weight="1"
                android:layout_width="0px" android:layout_height="wrap_content" />

    </LinearLayout>

</LinearLayout>

And this is the xml for the content inside each Fragment.

labeled_text_edit.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="4dip" >

    <TextView
        android:id="@+id/msg"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0"
        android:paddingBottom="4dip" />

    <EditText
        android:id="@+id/saved"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:background="@android:color/holo_blue_light"
        android:freezesText="true"
        android:text="I am in a Fragment" >

        <requestFocus />
    </EditText>

</LinearLayout>

FragmentHideShow.java

package com.example.fragmentshowingandhiding;

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;

/**
 * Demonstration of hiding and showing fragments.
 */
public class FragmentHideShow extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_hide_show);

        // The content view embeds two fragments; now retrieve them and attach
        // their "hide" button.
        FragmentManager fm = getFragmentManager();
        addShowHideListener(R.id.frag1hide, fm.findFragmentById(R.id.fragment1));
        addShowHideListener(R.id.frag2hide, fm.findFragmentById(R.id.fragment2));
    }

    void addShowHideListener(int buttonId, final Fragment fragment) {
        final Button button = (Button)findViewById(buttonId);
        button.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                FragmentTransaction ft = getFragmentManager().beginTransaction();
                ft.setCustomAnimations(android.R.animator.fade_in,
                        android.R.animator.fade_out);
                if (fragment.isHidden()) {
                    ft.show(fragment);
                    button.setText("Hide");
                } else {
                    ft.hide(fragment);
                    button.setText("Show");
                }
                ft.commit();
            }
        });
    }

    public static class FirstFragment extends Fragment {
        TextView mTextView;

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View v = inflater.inflate(R.layout.labeled_text_edit, container, false);
            View tv = v.findViewById(R.id.msg);
            ((TextView)tv).setText("The fragment saves and restores this text.");

            // Retrieve the text editor, and restore the last saved state if needed.
            mTextView = (TextView)v.findViewById(R.id.saved);
            if (savedInstanceState != null) {
                mTextView.setText(savedInstanceState.getCharSequence("text"));
            }
            return v;
        }

        @Override
        public void onSaveInstanceState(Bundle outState) {
            super.onSaveInstanceState(outState);

            // Remember the current text, to restore if we later restart.
            outState.putCharSequence("text", mTextView.getText());
        }
    }

    public static class SecondFragment extends Fragment {

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View v = inflater.inflate(R.layout.labeled_text_edit, container, false);
            View tv = v.findViewById(R.id.msg);
            ((TextView)tv).setText("The TextView saves and restores this text.");

            // Retrieve the text editor and tell it to save and restore its state.
            // Note that you will often set this in the layout XML, but since
            // we are sharing our layout with the other fragment we will customize
            // it here.
            ((TextView)v.findViewById(R.id.saved)).setSaveEnabled(true);
            return v;
        }
    }
}

You can download the complete source code for the above example from here.

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