MainActivity.java

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/*
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* Copyright 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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*     http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.example.android.batchstepsensor;
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import android.os.Bundle;
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import android.support.v4.app.FragmentManager;
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import android.support.v4.app.FragmentTransaction;
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import android.view.Menu;
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import com.example.android.common.activities.SampleActivityBase;
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import com.example.android.common.logger.Log;
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public class MainActivity extends SampleActivityBase implements CardStream {
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    public static final String TAG = "MainActivity";
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    public static final String FRAGTAG = "BatchStepSensorFragment";
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    private CardStreamFragment mCardStreamFragment;
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    private StreamRetentionFragment mRetentionFragment;
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    private static final String RETENTION_TAG = "retention";
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    @Override
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    protected void onCreate(Bundle savedInstanceState) {
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        super.onCreate(savedInstanceState);
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        setContentView(R.layout.activity_main);
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        FragmentManager fm = getSupportFragmentManager();
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        BatchStepSensorFragment fragment =
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                (BatchStepSensorFragment) fm.findFragmentByTag(FRAGTAG);
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        if (fragment == null) {
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            FragmentTransaction transaction = fm.beginTransaction();
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            fragment = new BatchStepSensorFragment();
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            transaction.add(fragment, FRAGTAG);
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            transaction.commit();
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        }
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        // Use fragment as click listener for cards, but must implement correct interface
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        if(!(fragment instanceof OnCardClickListener)){
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            throw new ClassCastException("BatchStepSensorFragment must " +
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                    "implement OnCardClickListener interface.");
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        }
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        OnCardClickListener clickListener = (OnCardClickListener) fm.findFragmentByTag(FRAGTAG);
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        mRetentionFragment = (StreamRetentionFragment) fm.findFragmentByTag(RETENTION_TAG);
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        if (mRetentionFragment == null) {
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            mRetentionFragment = new StreamRetentionFragment();
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            fm.beginTransaction().add(mRetentionFragment, RETENTION_TAG).commit();
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        } else {
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            // If the retention fragment already existed, we need to pull some state.
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            // pull state out
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            CardStreamState state = mRetentionFragment.getCardStream();
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            // dump it in CardStreamFragment.
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            mCardStreamFragment =
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                    (CardStreamFragment) fm.findFragmentById(R.id.fragment_cardstream);
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            mCardStreamFragment.restoreState(state, clickListener);
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        }
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    }
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    public CardStreamFragment getCardStream() {
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        if (mCardStreamFragment == null) {
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            mCardStreamFragment = (CardStreamFragment)
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                    getSupportFragmentManager().findFragmentById(R.id.fragment_cardstream);
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        }
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        return mCardStreamFragment;
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    }
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    @Override
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    protected void onSaveInstanceState(Bundle outState) {
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        super.onSaveInstanceState(outState);
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        CardStreamState state = getCardStream().dumpState();
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        mRetentionFragment.storeCardStream(state);
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    }
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}