4月21日，使用格式化字符串，Android 开发，每日20行，第43天。

本文介绍了一个犯罪记录应用的完整架构，包括数据模型定义、数据库设计、数据访问层实现及UI层交互逻辑。该应用利用SQLite数据库存储犯罪记录，并通过自定义的数据访问层提供高效的数据操作接口。

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CrimeBaseHelper.java

package com.example.aster.criminalintent.database.CrimeDbSchema;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import com.example.aster.criminalintent.Crime;
import com.example.aster.criminalintent.database.CrimeDbSchema.CrimeDbSchema.CrimeTable;

public class CrimeBaseHelper extends SQLiteOpenHelper {
    private static final int VERSION = 1;
    private static final String DATABASE_NAME = "crimeBase.db";

    public CrimeBaseHelper(Context context) {
        super(context, DATABASE_NAME, null, VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table " + CrimeTable.NAME + "(" +
                " _id integer primary key autoincrement, " +
                CrimeTable.Cols.UUID + "," +
                CrimeTable.Cols.TITLE + "," +
                CrimeTable.Cols.DATE + "," +
                CrimeTable.Cols.SOLVED +
                ")"
        );
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

CrimeCursorWrapper.java

package com.example.aster.criminalintent.database.CrimeDbSchema;

import android.database.Cursor;
import android.database.CursorWrapper;

import com.example.aster.criminalintent.Crime;

import java.util.Date;
import java.util.UUID;

import static com.example.aster.criminalintent.database.CrimeDbSchema.CrimeDbSchema.*;

public class CrimeCursorWrapper extends CursorWrapper {
    public CrimeCursorWrapper(Cursor cursor) {
        super(cursor);
    }

    public Crime getCrime() {
        String uuidString = getString(getColumnIndex(CrimeTable.Cols.UUID));
        String title = getString(getColumnIndex(CrimeTable.Cols.TITLE));
        long date = getLong(getColumnIndex(CrimeTable.Cols.DATE));
        int isSolved = getInt(getColumnIndex(CrimeTable.Cols.SOLVED));

        Crime crime = new Crime(UUID.fromString(uuidString));
        crime.setTitle(title);
        crime.setDate(new Date(date));
        crime.setSolved(isSolved != 0);

        return crime;
    }
}

CrimeDbSchema

package com.example.aster.criminalintent.database.CrimeDbSchema;

public class CrimeDbSchema {
    public static final class CrimeTable {
        public static final String NAME = "crimes";

        public static final class Cols {
            public static final String UUID = "uuid";
            public static final String TITLE = "title";
            public static final String DATE = "date";
            public static final String SOLVED = "solved";
        }
    }
}

Crime.java

package com.example.aster.criminalintent;

import java.util.Date;
import java.util.UUID;

public class Crime {

    private UUID mId;
    private String mTitle;
    private Date mDate;
    private boolean mSolved;

    public Crime() {
        this(UUID.randomUUID());
    }

    public Crime(UUID id) {
        mId = id;
        mDate = new Date();
    }

    public UUID getId() {
        return mId;
    }

    public String getTitle() {
        return mTitle;
    }

    public void setTitle(String title) {
        mTitle = title;
    }

    public Date getDate() {
        return mDate;
    }

    public void setDate(Date date) {
        mDate = date;
    }

    public boolean isSolved() {
        return mSolved;
    }

    public void setSolved(boolean solved) {
        mSolved = solved;
    }
}

CrimeFragment.java

package com.example.aster.criminalintent;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.EditText;

import java.text.DateFormat;
import java.util.Date;
import java.util.UUID;

import static android.widget.CompoundButton.*;

public class CrimeFragment extends Fragment {

    private static final String ARG_CRIME_ID = "crime_id";
    private static final String DIALOG_DATE = "DialogDate";

    private static final int REQUEST_DATE = 0;

    private Crime mCrime;
    private EditText mTitleField;
    private Button mDateButton;
    private CheckBox mSolvedCheckBox;

    public static CrimeFragment newInstance(UUID crimeId) {
        Bundle args = new Bundle();
        args.putSerializable(ARG_CRIME_ID, crimeId);

        CrimeFragment fragment = new CrimeFragment();
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        UUID crimeId = (UUID) getArguments().getSerializable(ARG_CRIME_ID);
        mCrime = CrimeLab.get(getActivity()).getCrime(crimeId);
    }

    @Override
    public void onPause() {
        super.onPause();

        CrimeLab.get(getActivity())
                .updateCrime(mCrime);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_crime, container, false);

        mTitleField = (EditText) v.findViewById(R.id.crime_title);
        mTitleField.setText(mCrime.getTitle());
        mTitleField.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
                // This space intentionally left blank
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                mCrime.setTitle(s.toString());
            }

            @Override
            public void afterTextChanged(Editable s) {
                // This one too
            }
        });

        mDateButton = (Button) v.findViewById(R.id.crime_date);
        updateDate();
        mDateButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                FragmentManager manager = getFragmentManager();
                DatePickerFragment dialog = DatePickerFragment
                        .newInstance(mCrime.getDate());
                dialog.setTargetFragment(CrimeFragment.this, REQUEST_DATE);
                dialog.show(manager, DIALOG_DATE);
            }
        });

        mSolvedCheckBox = (CheckBox) v.findViewById(R.id.crime_solved);
        mSolvedCheckBox.setChecked(mCrime.isSolved());
        mSolvedCheckBox.setOnCheckedChangeListener(new OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                mCrime.setSolved(isChecked);
            }
        });

        return v;
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode != Activity.RESULT_OK) {
            return;
        }

        if (requestCode == REQUEST_DATE) {
            Date date = (Date) data
                    .getSerializableExtra(DatePickerFragment.EXTRA_DATE);
            mCrime.setDate(date);
            updateDate();
        }
    }

    private void updateDate() {
        mDateButton.setText(mCrime.getDate().toString());
    }

    private String getCrimeReport() {
        String solvedString = null;
        if (mCrime.isSolved()) {
            solvedString = getString(R.string.crime_report_solved);
        } else {
            solvedString = getString(R.string.crime_report_unsolved);
        }

        String dateFormat = "EEE, MMM dd";
        String dateString = android.text.format.DateFormat.format(dateFormat, mCrime.getDate()).toString();

        String suspect = mCrime.getSuspect();
        if (suspect == null) {
            suspect = getString(R.string.crime_report_no_suspect);
        } else {
            suspect = getString(R.string.crime_report_suspect, suspect);
        }

        String report = getString(R.string.crime_report,
                mCrime.getTitle(), dateString, solvedString, suspect);

        return report;
    }
}

CrimeLab.java

package com.example.aster.criminalintent;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

import com.example.aster.criminalintent.database.CrimeDbSchema.CrimeBaseHelper;
import com.example.aster.criminalintent.database.CrimeDbSchema.CrimeCursorWrapper;
import com.example.aster.criminalintent.database.CrimeDbSchema.CrimeDbSchema;

import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

import static com.example.aster.criminalintent.database.CrimeDbSchema.CrimeDbSchema.*;

public class CrimeLab {
    private static CrimeLab sCrimeLab;

    private Context mContext;
    private SQLiteDatabase mDatabase;

    public static CrimeLab get(Context context) {
        if (sCrimeLab == null) {
            sCrimeLab = new CrimeLab(context);
        }
        return sCrimeLab;
    }

    private CrimeLab(Context context) {
        mContext = context.getApplicationContext();
        mDatabase = new CrimeBaseHelper(mContext)
                .getWritableDatabase();
    }

    public void addCrime(Crime c) {
        ContentValues values = getContentValues(c);

        mDatabase.insert(CrimeTable.NAME, null, values);
    }

    public List<Crime> getCrimes() {
        List<Crime> crimes = new ArrayList<>();

        CrimeCursorWrapper cursor = queryCrimes(null, null);

        try {
            cursor.moveToFirst();
            while (!cursor.isAfterLast()) {
                crimes.add(cursor.getCrime());
                cursor.moveToNext();
            }
        } finally {
            cursor.close();
        }

        return crimes;
    }

    public Crime getCrime(UUID id) {
        CrimeCursorWrapper cursor = queryCrimes(
                CrimeTable.Cols.UUID + " = ?",
                new String[] { id.toString() }
        );

        try {
            if (cursor.getCount() == 0) {
                return null;
            }

            cursor.moveToFirst();
            return cursor.getCrime();
        } finally {
            cursor.close();
        }
    }

    public void updateCrime(Crime crime) {
        String uuidString = crime.getId().toString();
        ContentValues values = getContentValues(crime);
        mDatabase.update(CrimeTable.NAME, values,
                CrimeTable.Cols.UUID + " = ?",
                new String[] { uuidString });
    }

    private CrimeCursorWrapper queryCrimes(String whereClause, String[] whereArgs) {
        Cursor cursor = mDatabase.query(
                CrimeTable.NAME,
                null, // Columns - null selects all columns
                whereClause,
                whereArgs,
                null, // groupBy
                null, // having
                null // orderBy
        );

        return new CrimeCursorWrapper(cursor);
    }

    private static ContentValues getContentValues(Crime crime) {
        ContentValues values = new ContentValues();
        values.put(CrimeTable.Cols.UUID, crime.getId().toString());
        values.put(CrimeTable.Cols.TITLE, crime.getTitle());
        values.put(CrimeTable.Cols.DATE, crime.getDate().getTime());
        values.put(CrimeTable.Cols.SOLVED, crime.isSolved() ? 1 : 0);

        return values;
    }
}

CrimeListActivity.java

package com.example.aster.criminalintent;

import android.support.v4.app.Fragment;

public class CrimeListActivity extends SingleFragmentActivity {

    @Override
    protected Fragment createFragment() {
        return new CrimeListFragment();
    }
}

CrimeListFragment.java

package com.example.aster.criminalintent;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;

public class CrimeListFragment extends Fragment {

    private static final String SAVED_SUBTITLE_VISIBLE = "subtitle";

    private RecyclerView mCrimeRecyclerView;
    private CrimeAdapter mAdapter;
    private boolean mSubtitleVisible;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setHasOptionsMenu(true);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_crime_list, container, false);

        mCrimeRecyclerView = (RecyclerView) view.findViewById(R.id.crime_recycler_view);
        mCrimeRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

        if (savedInstanceState != null) {
            mSubtitleVisible = savedInstanceState.getBoolean(SAVED_SUBTITLE_VISIBLE);
        }

        updateUI();

        return view;
    }

    @Override
    public void onResume() {
        super.onResume();
        updateUI();
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putBoolean(SAVED_SUBTITLE_VISIBLE, mSubtitleVisible);
    }

    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        super.onCreateOptionsMenu(menu, inflater);
        inflater.inflate(R.menu.fragment_crime_list, menu);

        MenuItem subtitleItem = menu.findItem(R.id.show_subtitle);
        if (mSubtitleVisible) {
            subtitleItem.setTitle(R.string.hide_subtitle);
        } else {
            subtitleItem.setTitle(R.string.show_subtitle);
        }
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.new_crime:
                Crime crime = new Crime();
                CrimeLab.get(getActivity()).addCrime(crime);
                Intent intent = CrimePagerActivity
                        .newIntent(getActivity(), crime.getId());
                startActivity(intent);
                return true;
            case R.id.show_subtitle:
                mSubtitleVisible = !mSubtitleVisible;
                getActivity().invalidateOptionsMenu();
                updateSubtitle();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    private void updateSubtitle() {
        CrimeLab crimeLab = CrimeLab.get(getActivity());
        int crimeCount = crimeLab.getCrimes().size();
        String subtitle = getString(R.string.subtitlt_format, crimeCount);

        if (!mSubtitleVisible) {
            subtitle = null;
        }

        AppCompatActivity activity = (AppCompatActivity) getActivity();
        activity.getSupportActionBar().setSubtitle(subtitle);
    }

    private void updateUI() {
        CrimeLab crimeLab = CrimeLab.get(getActivity());
        List<Crime> crimes = crimeLab.getCrimes();

        if (mAdapter == null) {
            mAdapter = new CrimeAdapter(crimes);
            mCrimeRecyclerView.setAdapter(mAdapter);
        } else {
            mAdapter.setCrimes(crimes);
            mAdapter.notifyDataSetChanged();
        }

        updateSubtitle();
    }

    private class CrimeHolder extends RecyclerView.ViewHolder
            implements View.OnClickListener {

        private Crime mCrime;
        private TextView mTitleTextView;
        private TextView mDateTextView;
        private ImageView mSolvedImageView;

        public CrimeHolder(LayoutInflater inflater, ViewGroup parent) {
            super(inflater.inflate(R.layout.list_item_crime, parent, false));
            itemView.setOnClickListener(this);

            mTitleTextView = (TextView) itemView.findViewById(R.id.crime_title);
            mDateTextView = (TextView) itemView.findViewById(R.id.crime_date);
            mSolvedImageView = (ImageView) itemView.findViewById(R.id.crime_solved);
        }

        public void bind(Crime crime) {
            mCrime = crime;
            mTitleTextView.setText(mCrime.getTitle());
            mDateTextView.setText(mCrime.getDate().toString());
            mSolvedImageView.setVisibility(crime.isSolved() ? View.VISIBLE : View.GONE);
        }

        @Override
        public void onClick(View view) {
            Intent intent = CrimePagerActivity.newIntent(getActivity(), mCrime.getId());
            startActivity(intent);
        }
    }

    private class CrimeAdapter extends RecyclerView.Adapter<CrimeHolder> {

        private List<Crime> mCrimes;

        public CrimeAdapter(List<Crime> crimes) {
            mCrimes = crimes;
        }

        @Override
        public CrimeHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            LayoutInflater layoutInflater = LayoutInflater.from(getActivity());

            return new CrimeHolder(layoutInflater, parent);
        }

        @Override
        public void onBindViewHolder(CrimeHolder holder, int position) {
            Crime crime = mCrimes.get(position);
            holder.bind(crime);
        }

        @Override
        public int getItemCount() {
            return mCrimes.size();
        }

        public void setCrimes(List<Crime> crimes) {
            mCrimes = crimes;
        }
    }

}

CrimePagerActivity.java

package com.example.aster.criminalintent;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;

import java.util.List;
import java.util.UUID;

public class CrimePagerActivity extends AppCompatActivity {
    private static final String EXTRA_CRIME_ID =
            "com.example.aster.criminalintent.crime_id";

    private ViewPager mViewPager;
    private List<Crime> mCrimes;

    public static Intent newIntent(Context packageContext, UUID crimeId) {
        Intent intent = new Intent(packageContext, CrimePagerActivity.class);
        intent.putExtra(EXTRA_CRIME_ID, crimeId);
        return intent;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_crime_pager);

        UUID crimeId = (UUID) getIntent()
                .getSerializableExtra(EXTRA_CRIME_ID);

        mViewPager = (ViewPager) findViewById(R.id.crime_view_pager);

        mCrimes = CrimeLab.get(this).getCrimes();
        FragmentManager fragmentManager = getSupportFragmentManager();
        mViewPager.setAdapter(new FragmentStatePagerAdapter(fragmentManager) {

            @Override
            public Fragment getItem(int position) {
                Crime crime = mCrimes.get(position);
                return CrimeFragment.newInstance(crime.getId());
            }

            @Override
            public int getCount() {
                return mCrimes.size();
            }
        });

        for (int i = 0; i < mCrimes.size(); i++) {
            if (mCrimes.get(i).getId().equals(crimeId)) {
                mViewPager.setCurrentItem(i);
                break;
            }
        }
    }
}

DatePickerFragment.java

package com.example.aster.criminalintent;

import android.app.Activity;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.DialogFragment;
import android.support.v7.app.AlertDialog;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.DatePicker;

import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

public class DatePickerFragment extends DialogFragment {

    public static final String EXTRA_DATE =
            "com.example.aster.criminalintent.date";

    private static final String ARG_DATE = "date";

    private DatePicker mDatePicker;

    public static DatePickerFragment newInstance(Date date) {
        Bundle args = new Bundle();
        args.putSerializable(ARG_DATE, date);

        DatePickerFragment fragment = new DatePickerFragment();
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        Date date = (Date) getArguments().getSerializable(ARG_DATE);

        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH);
        int day = calendar.get(Calendar.DAY_OF_MONTH);

        View v = LayoutInflater.from(getActivity())
                .inflate(R.layout.dialog_date, null);

        mDatePicker = (DatePicker) v.findViewById(R.id.dialog_date_picker);
        mDatePicker.init(year, month, day, null);

        return new AlertDialog.Builder(getActivity())
                .setView(v)
                .setTitle(R.string.date_picker_title)
                .setPositiveButton(android.R.string.ok,
                        new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                int year = mDatePicker.getYear();
                                int month = mDatePicker.getMonth();
                                int day = mDatePicker.getDayOfMonth();
                                Date date = new  GregorianCalendar(year, month, day).getTime();
                                sendResult(Activity.RESULT_OK, date);
                            }
                        })
                .create();
    }

    private void sendResult(int resultCode, Date date) {
        if (getTargetFragment() == null) {
            return;
        }
        Intent intent = new Intent();
        intent.putExtra(EXTRA_DATE, date);

        getTargetFragment()
                .onActivityResult(getTargetRequestCode(), resultCode, intent);
    }
}

SingleFragmentActivity.java

package com.example.aster.criminalintent;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v7.app.AppCompatActivity;

public abstract class SingleFragmentActivity extends AppCompatActivity {

    protected abstract Fragment createFragment();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_fragment);

        FragmentManager fm = getSupportFragmentManager();
        Fragment fragment = fm.findFragmentById(R.id.fragment_container);

        if (fragment == null) {
            fragment = createFragment();
            fm.beginTransaction().add(R.id.fragment_container, fragment).commit();
        }
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.aster.criminalintent">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".CrimeListActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
            <activity android:name=".CrimePagerActivity"
                      android:parentActivityName=".CrimeListActivity">
        </activity>
    </application>

</manifest>

activity_crime_pager.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/crime_view_pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

</android.support.v4.view.ViewPager>

activity_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragment_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

dialog_date.xml

<?xml version="1.0" encoding="utf-8"?>
<DatePicker
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/dialog_date_picker"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:calendarViewShown="false">

</DatePicker>

fragment_crime.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="16dp"
    android:orientation="vertical">

    <TextView
        style="?android:listSeparatorTextViewStyle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/crime_title_label" />

    <EditText
        android:id="@+id/crime_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/crime_title_hint" />

    <TextView
        style="?android:listSeparatorTextViewStyle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/crime_details_label" />

    <Button
        android:id="@+id/crime_date"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <CheckBox
        android:id="@+id/crime_solved"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/crime_solved_label" />

    <Button
        android:id="@+id/crime_suspect"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/crime_suspect_text" />

    <Button
        android:id="@+id/crime_report"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/crime_report_text" />

</LinearLayout>

fragment_crime_list.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.RecyclerView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/crime_recycler_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

menu/fragment_crime_list.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/new_crime"
        android:icon="@drawable/ic_menu_add"
        android:title="@string/new_crime"
        app:showAsAction="ifRoom|withText"/>

    <item
        android:id="@+id/show_subtitle"
        android:title="@string/show_subtitle"
        app:showAsAction="ifRoom"/>
</menu>

list_item_crime.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/linearLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    tools:layout_editor_absoluteY="81dp">

    <TextView
        android:id="@+id/crime_title"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:text="Crime Title"
        app:layout_constraintEnd_toStartOf="@+id/crime_solved"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/crime_date"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="16dp"
        android:layout_marginTop="8dp"
        android:text="Crime Date"
        app:layout_constraintEnd_toStartOf="@+id/crime_solved"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/crime_title" />

    <ImageView
        android:id="@+id/crime_solved"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginTop="16dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:srcCompat="@drawable/ic_solved" />

</android.support.constraint.ConstraintLayout>

strings.xml

<resources>
    <string name="app_name">CriminalIntent</string>
    <string name="crime_title_hint">Enter a title for the crime.</string>
    <string name="crime_title_label">Title</string>
    <string name="crime_details_label">Details</string>
    <string name="crime_solved_label">Solved</string>
    <string name="date_picker_title">Date of crime:</string>
    <string name="new_crime">New Crime</string>
    <string name="show_subtitle">Show Subtitle</string>
    <string name="hide_subtitle">Hide Subtitle</string>
    <string name="subtitle_format">%1$d crimes</string>
    <string name="crime_suspect_text">Choose Suspect</string>
    <string name="crime_report_text">Send Crime Report</string>
    <string name="crime_report">%1$s!
        The crime was discovered on %2$s. %3$s, %4$s</string>
    <string name="crime_report_solved">The case is solved</string>
    <string name="crime_report_unsolved">The case is not solved</string>
    <string name="crime_report_no_suspect">there is no suspect.</string>
    <string name="crime_report_suspect">the suspect is %s.</string>
    <string name="crime_report_subject">CriminalIntent Crime Report</string>
    <string name="send_report">Send crime report via</string>
</resources>