blainelewis1.cmput301assignment1.ClaimManager.java Source code

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Here is the source code for blainelewis1.cmput301assignment1.ClaimManager.java

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/*
    
Copyright 2015 Blaine Lewis
    
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.
    
*/

package blainelewis1.cmput301assignment1;

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.lang.reflect.Type;
import java.util.ArrayList;

import android.content.Context;
import android.util.Log;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

/*
 * This is a singleton that manages the list of claims by 
 * providing means of (de) serialization and interfaces to get all of the claims
 * 
 * It's a singleton just to make accessing claims easier as well as keeping serialization consistent
 */

public class ClaimManager {

    private static ClaimManager instance = null;

    //This is the name of the file we serialize to, it's arbitrary...
    private static final String saveFileName = "claims.sav";

    private ArrayList<Claim> claims;

    protected ClaimManager() {

    }

    /*
     * Returns an instance of the claimManager
     */

    public static ClaimManager getInstance() {
        if (instance == null) {
            instance = new ClaimManager();
        }
        return instance;
    }

    /*
     * Adds a claim to the list
     */

    public void addClaim(Claim claim) {
        claims.add(claim);
    }

    public Claim createNewClaim() {
        Claim claim = new Claim();

        addClaim(claim);

        return claim;
    }

    /*
     * Finds a claim by its id
     */

    public Claim getClaimById(String id) {
        for (Claim claim : claims) {
            if (claim.getId().equals(id)) {
                return claim;
            }
        }

        return null;
    }

    /*
     * Creates an expense from it's claim. 
     * We manage expense creation to ensure it is done properly
     */

    public Expense createNewExpense(Claim claim) {
        Expense expense = new Expense(claim);

        claim.addExpense(expense);

        return expense;
    }

    /*
     * Deletes a claim
     */

    public void deleteClaim(Claim claim) {
        claims.remove(claim);
    }

    /*
     * Serializes the claims as JSON using GSON 
     */

    public void serialize(Context context) {

        //Why write nothing?
        if (this.claims == null) {
            return;
        }

        Gson gson = new Gson();

        try {

            OutputStreamWriter writer = new OutputStreamWriter(
                    context.openFileOutput(saveFileName, Context.MODE_PRIVATE));

            gson.toJson(claims, writer);

            writer.close();

        } catch (IOException e) {
            // Fail silently, we can't do anything about this...
            Log.e("Error", "Serialize failed", e);
        }

    }

    /*
     * Deserializes the claims that are stored as JSON using GSON 
     */

    public void deserialize(Context context) {

        //Deserializing while we already have claims is dangerous and will overwrite data
        if (this.claims != null) {
            return;
        }

        Gson gson = new Gson();

        try {

            InputStreamReader reader = new InputStreamReader(context.openFileInput(saveFileName));

            //https://sites.google.com/site/gson/gson-user-guide 02-02-2015 Blaine Lewis

            Type arrayListType = new TypeToken<ArrayList<Claim>>() {
            }.getType();

            claims = gson.fromJson(reader, arrayListType);

            reader.close();

        } catch (IOException e) {
            // fail silently there's nothing else we can do
            Log.e("Error", "Deserialize failed", e);
        }

        //Either we failed to load the claims or there were none

        if (claims == null) {
            claims = new ArrayList<Claim>();
        }

    }

    /*
     * Returns all the claims
     */
    public ArrayList<Claim> getClaims() {
        return claims;
    }

}