Android How to - Save State during orientation change

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The following code shows how to Save State during orientation change.

Example

res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
  <Button android:id="@+id/pick"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:layout_weight="1"
    android:text="Pick"
    android:enabled="true"
  />
  <Button android:id="@+id/view"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:layout_weight="1"
    android:text="View"
    android:enabled="false"
  />
</LinearLayout>

res/layout-land/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="horizontal"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
  <Button android:id="@+id/pick"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:layout_weight="1"
    android:text="Pick"
    android:enabled="true"
  />
  <Button android:id="@+id/view"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:layout_weight="1"
    android:text="View"
    android:enabled="false"
  />
</LinearLayout>

Java code

//from   www  .  j  a  va 2 s . c  o  m
/* Copyright (c) 2008-2009 -- CommonsWare, LLC

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/
   

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.util.Log;

public class MainActivity extends Activity {
  static final int PICK_REQUEST=1337;
  Button viewButton=null;
  Uri contact=null;
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    
    Button btn=(Button)findViewById(R.id.pick);
    
    btn.setOnClickListener(new View.OnClickListener() {
      public void onClick(View view) {
        Intent i=new Intent(Intent.ACTION_PICK,
                    Uri.parse("content://contacts/people"));

        startActivityForResult(i, PICK_REQUEST);
      }
    });
    
    viewButton=(Button)findViewById(R.id.view);
    
    viewButton.setOnClickListener(new View.OnClickListener() {
      public void onClick(View view) {
        startActivity(new Intent(Intent.ACTION_VIEW, contact));
      }
    });
    
    restoreMe(savedInstanceState);
    
    viewButton.setEnabled(contact!=null);
  }

  @Override
  protected void onActivityResult(int requestCode, int resultCode,
                                    Intent data) {
    if (requestCode==PICK_REQUEST) {
      if (resultCode==RESULT_OK) {
        contact=data.getData();
        viewButton.setEnabled(true);
      }
    }
  }

  @Override
  protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    
    if (contact!=null) {
      outState.putString("contact", contact.toString());
    }
  }
  
  private void restoreMe(Bundle state) {
    contact=null;
    
    if (state!=null) {
      String contactUri=state.getString("contact");
      
      if (contactUri!=null) {
        contact=Uri.parse(contactUri);
      }
    }
  }
}

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