Java tutorial
/*** Copyright (c) 2012 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. From _The Busy Coder's Guide to Android Development_ http://commonsware.com/Android */ package com.commonsware.android.anim.threepane; import android.os.Bundle; import android.support.v4.app.FragmentActivity; import android.widget.Button; import java.util.ArrayList; public class MainActivity extends FragmentActivity { private static final String KEY_MIDDLE_CONTENTS = "middleContents"; private static final String[] items = { "lorem", "ipsum", "dolor", "sit", "amet", "consectetuer", "adipiscing", "elit", "morbi", "vel", "ligula", "vitae", "arcu", "aliquet", "mollis", "etiam", "vel", "erat", "placerat", "ante", "porttitor", "sodales", "pellentesque", "augue", "purus" }; private boolean isLeftShowing = true; private SimpleListFragment middleFragment = null; private ArrayList<String> middleContents = null; private ThreePaneLayout root = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); root = (ThreePaneLayout) findViewById(R.id.root); if (getSupportFragmentManager().findFragmentById(R.id.left) == null) { getSupportFragmentManager().beginTransaction().add(R.id.left, SimpleListFragment.newInstance(items)) .commit(); } middleFragment = (SimpleListFragment) getSupportFragmentManager().findFragmentById(R.id.middle); } @Override public void onBackPressed() { if (!isLeftShowing) { root.showLeft(); isLeftShowing = true; } else { super.onBackPressed(); } } @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putStringArrayList(KEY_MIDDLE_CONTENTS, middleContents); } @Override protected void onRestoreInstanceState(Bundle inState) { middleContents = inState.getStringArrayList(KEY_MIDDLE_CONTENTS); } void onListItemClick(SimpleListFragment fragment, int position) { if (fragment == middleFragment) { ((Button) root.getRightView()).setText(middleContents.get(position)); if (isLeftShowing) { root.hideLeft(); isLeftShowing = false; } } else { middleContents = new ArrayList<String>(); for (int i = 0; i < 20; i++) { middleContents.add(items[position] + " #" + i); } if (getSupportFragmentManager().findFragmentById(R.id.middle) == null) { middleFragment = SimpleListFragment.newInstance(middleContents); getSupportFragmentManager().beginTransaction().add(R.id.middle, middleFragment).commit(); } else { middleFragment.setContents(middleContents); } } } }