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.activityinstrumentation;
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import android.app.Activity;
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import android.content.SharedPreferences;
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import android.os.Bundle;
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import android.preference.PreferenceManager;
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import android.view.View;
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import android.widget.AdapterView;
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import android.widget.ArrayAdapter;
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import android.widget.Spinner;
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import java.util.ArrayList;
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import java.util.Arrays;
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/**
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 * Basic activity with a spinner. The spinner should persist its position to disk every time a
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 * new selection is made.
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 */
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public class MainActivity extends Activity {
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    /** Shared preferences key: Holds spinner position. Must not be negative. */
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    private static final String PREF_SPINNER_POS = "spinner_pos";
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    /** Magic constant to indicate that no value is stored for PREF_SPINNER_POS. */
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    private static final int PREF_SPINNER_VALUE_ISNULL = -1;
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    /** Values for display in spinner. */
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    private static final String[] SPINNER_VALUES = new String[] {
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            "Select Weather...", "Sunny", "Partly Cloudy", "Cloudy", "Rain", "Snow", "Hurricane"};
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    // Constants representing each of the options in SPINNER_VALUES. Declared package-private
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    // so that they can be accessed from our test suite.
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static final int WEATHER_NOSELECTION = 0;
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    static final int WEATHER_SUNNY = 1;
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    static final int WEATHER_PARTLY_CLOUDY = 2;
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    static final int WEATHER_CLOUDY = 3;
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    static final int WEATHER_RAIN = 4;
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    static final int WEATHER_SNOW = 5;
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    static final int WEATHER_HURRICANE = 6;
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    /** Handle to default shared preferences for this activity. */
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    private SharedPreferences mPrefs;
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    /** Handle to the spinner in this Activity's layout. */
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    private Spinner mSpinner;
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    /**
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     * Setup activity state.
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     *
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     * @param savedInstanceState
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     */
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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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        // Inflate UI from res/layout/activity_main.xml
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        setContentView(R.layout.sample_main);
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        // Get handle to default shared preferences for this activity
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        mPrefs = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
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        // Populate spinner with sample values from an array
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        mSpinner = (Spinner) findViewById(R.id.spinner);
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        mSpinner.setAdapter(
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                new ArrayAdapter<String>(
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                        this,                                                   // Context
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                        android.R.layout.simple_list_item_1,                    // Layout
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                        new ArrayList<String>(Arrays.asList(SPINNER_VALUES))    // Data source
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                ));
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        // Read in a sample value, if it's not set.
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        int selection = mPrefs.getInt(PREF_SPINNER_POS, PREF_SPINNER_VALUE_ISNULL);
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        if (selection != PREF_SPINNER_VALUE_ISNULL) {
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            mSpinner.setSelection(selection);
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        }
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        // Callback to persist spinner data whenever a new value is selected. This will be the
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        // focus of our sample unit test.
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        mSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
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            // The methods below commit the ID of the currently selected item in the spinner
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            // to disk, using a SharedPreferences file.
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            //
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            // Note: A common mistake here is to forget to call .commit(). Try removing this
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            // statement and running the tests to watch them fail.
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            @Override
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            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
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                mPrefs.edit().putInt(PREF_SPINNER_POS, position).commit();
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            }
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            @Override
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            public void onNothingSelected(AdapterView<?> parent) {
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                mPrefs.edit().remove(PREF_SPINNER_POS).commit();
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            }
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        });
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    }
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}