我有一个 Android 编程的 UI 实验室，我正在努力完成。我觉得我很近，但又很远。我有四个正在处理的 Activity ，但其中只有三个需要处理。这是我所拥有的。我需要帮助来解决我所缺少的。

这是第一个 Activity ，它是 AddToDoActivity

package course.labs.todomanager;
import java.util.Calendar;
import java.util.Date;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.app.TimePickerDialog;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener; 
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
import android.widget.TimePicker;
import course.labs.todomanager.ToDoItem.Priority;
import course.labs.todomanager.ToDoItem.Status;

public class AddToDoActivity extends Activity {

// 7 days in milliseconds - 7 * 24 * 60 * 60 * 1000
private static final int SEVEN_DAYS = 604800000;

private static final String TAG = "Lab-UserInterface";

private static String timeString;
private static String dateString;
private static TextView dateView;
private static TextView timeView;


private Date mDate;
private RadioGroup mPriorityRadioGroup;
private RadioGroup mStatusRadioGroup;
private EditText mTitleText;
private RadioButton mDefaultStatusButton;
private RadioButton mDefaultPriorityButton;

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

    mTitleText = (EditText) findViewById(R.id.title);
    mDefaultStatusButton = (RadioButton) findViewById(R.id.statusNotDone);
    mDefaultPriorityButton = (RadioButton) findViewById(R.id.medPriority);
    mPriorityRadioGroup = (RadioGroup) findViewById(R.id.priorityGroup);
    mStatusRadioGroup = (RadioGroup) findViewById(R.id.statusGroup);
    dateView = (TextView) findViewById(R.id.date);
    timeView = (TextView) findViewById(R.id.time);

    // Set the default date and time

    setDefaultDateTime();

    // OnClickListener for the Date button, calls showDatePickerDialog() to show
    // the Date dialog

    final Button datePickerButton = (Button) findViewById(R.id.date_picker_button);
    datePickerButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            showDatePickerDialog();
        }
    });

    // OnClickListener for the Time button, calls showTimePickerDialog() to show
    // the Time Dialog

    final Button timePickerButton = (Button) findViewById(R.id.time_picker_button);
    timePickerButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            showTimePickerDialog();
        }
    });

    // OnClickListener for the Cancel Button, 

    final Button cancelButton = (Button) findViewById(R.id.cancelButton);
    cancelButton.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            log("Entered cancelButton.OnClickListener.onClick()");

            //TODO - Implement onClick().  
            Intent intent = new Intent setResult;
            finish();
            
        }
    });

    //OnClickListener for the Reset Button

    final Button resetButton = (Button) findViewById(R.id.resetButton);
    resetButton.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            log("Entered resetButton.OnClickListener.onClick()");

            //TODO - Reset data fields to default values
            setDefaultDateTime();
            mTitleText.setText("");
            mDefaultStatusButton.setChecked(true);
            mDefaultPriorityButton.setChecked(true);
            
        
        
        
        }
    });

    // OnClickListener for the Submit Button
    // Implement onClick().
    
    final Button submitButton = (Button) findViewById(R.id.submitButton);
    submitButton.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            log("Entered submitButton.OnClickListener.onClick()");

            // Gather ToDoItem data  
            
            //TODO - Get Priority
            Priority priority = getPriority();

            //TODO -  Get Status
            Status status = getStatus();

            //TODO -  Title
            String titleString = mTitleText.getText().toString();

            // Date
            String fullDate = dateString + " " + timeString;

            // Package ToDoItem data into an Intent
            Intent data = new Intent();
            ToDoItem.packageIntent(data, titleString, priority, status, fullDate);

            //TODO - return data Intent and finish
            setResult(Activity.RESULT_OK, data);
            finish();
            
        }
    });
}

// Do not modify below here

// Use this method to set the default date and time

private void setDefaultDateTime() {

    // Default is current time + 7 days
    mDate = new Date();
    mDate = new Date(mDate.getTime() + SEVEN_DAYS);

    Calendar c = Calendar.getInstance();
    c.setTime(mDate);

    setDateString(c.get(Calendar.YEAR), c.get(Calendar.MONTH),
            c.get(Calendar.DAY_OF_MONTH));

    dateView.setText(dateString);

    setTimeString(c.get(Calendar.HOUR_OF_DAY), c.get(Calendar.MINUTE),
            c.get(Calendar.MILLISECOND));

    timeView.setText(timeString);
}

private static void setDateString(int year, int monthOfYear, int dayOfMonth) {

    // Increment monthOfYear for Calendar/Date -> Time Format setting
    monthOfYear++;
    String mon = "" + monthOfYear;
    String day = "" + dayOfMonth;

    if (monthOfYear < 10)
        mon = "0" + monthOfYear;
    if (dayOfMonth < 10)
        day = "0" + dayOfMonth;

    dateString = year + "-" + mon + "-" + day;
}

private static void setTimeString(int hourOfDay, int minute, int mili) {
    String hour = "" + hourOfDay;
    String min = "" + minute;

    if (hourOfDay < 10)
        hour = "0" + hourOfDay;
    if (minute < 10)
        min = "0" + minute;

    timeString = hour + ":" + min + ":00";
}

private Priority getPriority() {

    switch (mPriorityRadioGroup.getCheckedRadioButtonId()) {
    case R.id.lowPriority: {
        return Priority.LOW;
    }
    case R.id.highPriority: {
        return Priority.HIGH;
    }
    default: {
        return Priority.MED;
    }
    }
}

private Status getStatus() {

    switch (mStatusRadioGroup.getCheckedRadioButtonId()) {
    case R.id.statusDone: {
        return Status.DONE;
    }
    default: {
        return Status.NOTDONE;
    }
    }
}

// DialogFragment used to pick a ToDoItem deadline date

public static class DatePickerFragment extends DialogFragment implements
        DatePickerDialog.OnDateSetListener {

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {

        // Use the current date as the default date in the picker

        final Calendar c = Calendar.getInstance();
        int year = c.get(Calendar.YEAR);
        int month = c.get(Calendar.MONTH);
        int day = c.get(Calendar.DAY_OF_MONTH);

        // Create a new instance of DatePickerDialog and return it
        return new DatePickerDialog(getActivity(), this, year, month, day);
    }

    @Override
    public void onDateSet(DatePicker view, int year, int monthOfYear,
            int dayOfMonth) {
        setDateString(year, monthOfYear, dayOfMonth);

        dateView.setText(dateString);
    }

}

// DialogFragment used to pick a ToDoItem deadline time

public static class TimePickerFragment extends DialogFragment implements
        TimePickerDialog.OnTimeSetListener {

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {

        // Use the current time as the default values for the picker
        final Calendar c = Calendar.getInstance();
        int hour = c.get(Calendar.HOUR_OF_DAY);
        int minute = c.get(Calendar.MINUTE);

        // Create a new instance of TimePickerDialog and return
        return new TimePickerDialog(getActivity(), this, hour, minute,
                true);
    }

    public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
        setTimeString(hourOfDay, minute, 0);

        timeView.setText(timeString);
    }
}

private void showDatePickerDialog() {
    DialogFragment newFragment = new DatePickerFragment();
    newFragment.show(getFragmentManager(), "datePicker");
}

private void showTimePickerDialog() {
    DialogFragment newFragment = new TimePickerFragment();
    newFragment.show(getFragmentManager(), "timePicker");
}

private void log(String msg) {
    try {
        Thread.sleep(500);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    Log.i(TAG, msg);
}

}

这是第二个 Activity ToDoItem

package course.labs.todomanager;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import android.content.Intent;

// Do not modify 

public class ToDoItem {

public static final String ITEM_SEP = System.getProperty("line.separator");

public enum Priority {
    LOW, MED, HIGH
};

public enum Status {
    NOTDONE, DONE
};

public final static String TITLE = "title";
public final static String PRIORITY = "priority";
public final static String STATUS = "status";
public final static String DATE = "date";
public final static String FILENAME = "filename";

public final static SimpleDateFormat FORMAT = new SimpleDateFormat(
        "yyyy-MM-dd HH:mm:ss", Locale.US);

private String mTitle = new String();
private Priority mPriority = Priority.LOW;
private Status mStatus = Status.NOTDONE;
private Date mDate = new Date();

ToDoItem(String title, Priority priority, Status status, Date date) {
    this.mTitle = title;
    this.mPriority = priority;
    this.mStatus = status;
    this.mDate = date;
}

// Create a new ToDoItem from data packaged in an Intent

ToDoItem(Intent intent) {

    mTitle = intent.getStringExtra(ToDoItem.TITLE);
    mPriority = Priority.valueOf(intent.getStringExtra(ToDoItem.PRIORITY));
    mStatus = Status.valueOf(intent.getStringExtra(ToDoItem.STATUS));

    try {
        mDate = ToDoItem.FORMAT.parse(intent.getStringExtra(ToDoItem.DATE));
    } catch (ParseException e) {
        mDate = new Date();
    }
}

public String getTitle() {
    return mTitle;
}

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

public Priority getPriority() {
    return mPriority;
}

public void setPriority(Priority priority) {
    mPriority = priority;
}

public Status getStatus() {
    return mStatus;
}

public void setStatus(Status status) {
    mStatus = status;
}

public Date getDate() {
    return mDate;
}

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

// Take a set of String data values and 
// package them for transport in an Intent

public static void packageIntent(Intent intent, String title,
        Priority priority, Status status, String date) {

    intent.putExtra(ToDoItem.TITLE, title);
    intent.putExtra(ToDoItem.PRIORITY, priority.toString());
    intent.putExtra(ToDoItem.STATUS, status.toString());
    intent.putExtra(ToDoItem.DATE, date);

}

public String toString() {
    return mTitle + ITEM_SEP + mPriority + ITEM_SEP + mStatus + ITEM_SEP
            + FORMAT.format(mDate);
}

public String toLog() {
    return "Title:" + mTitle + ITEM_SEP + "Priority:" + mPriority
            + ITEM_SEP + "Status:" + mStatus + ITEM_SEP + "Date:"
            + FORMAT.format(mDate);
}

}

这是第三个 Activity ，它是 ToDoListAdapter

package course.labs.todomanager;

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

import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.RelativeLayout;
import android.widget.TextView;
import course.labs.todomanager.ToDoItem.Status;

public class ToDoListAdapter extends BaseAdapter {

// List of ToDoItems
private final List<ToDoItem> mItems = new ArrayList<ToDoItem>();

private final Context mContext;

private static final String TAG = "Lab-UserInterface";

public ToDoListAdapter(Context context) {

    mContext = context;

}

// Add a ToDoItem to the adapter
// Notify observers that the data set has changed

public void add(ToDoItem item) {

    mItems.add(item);
    notifyDataSetChanged();

}

// Clears the list adapter of all items.

public void clear(){

    mItems.clear();
    notifyDataSetChanged();

}

// Returns the number of ToDoItems

@Override
public int getCount() {

    return mItems.size();

}

// Retrieve the number of ToDoItems

@Override
public Object getItem(int pos) {

    return mItems.get(pos);

}

// Get the ID for the ToDoItem
// In this case it's just the position

@Override
public long getItemId(int pos) {

    return pos;

}

//Create a View to display the ToDoItem 
// at specified position in mItems

@Override
public View getView(int position, View convertView, ViewGroup parent) {


    //TODO - Get the current ToDoItem
    final ToDoItem toDoItem = getItemPos();

    //TODO - Inflate the View for this ToDoItem
    // from todo_item.xml.
    LayoutInflater = itemLayout;
    RelativeLayout itemLayout = m.context.getSystemService(R.layout.todo_item);
    
    //TODO - Fill in specific ToDoItem data
    // Remember that the data that goes in this View
    // corresponds to the user interface elements defined 
    // in the layout file 

    //TODO - Display Title in TextView

    final TextView titleView = ItemLayout.findViewById;
    setTextView;

    //TODO - Set up Status CheckBox

    final CheckBox statusView = ItemLayout.findViewById(R.id.statusCheckBox);
    statusView.setChecked(checked) statusDone;
    
    statusView.setOnCheckedChangeListener(new OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView,
                boolean isChecked) {
            log("Entered onCheckedChanged()");
            
            //TODO - Set up and implement an OnCheckedChangeListener, which 
            // is called when the user toggles the status checkbox
            if isChecked ToDoItem.setStatus status.Done(true);
            else

        
        }
    });

    //TODO - Display Priority in a TextView

    final TextView priorityView = findViewByID(R.id.PriorityView);
    PriorityView.setToString();

    
    //TODO - Display Time and Date. 
    // Hint - use ToDoItem.FORMAT.format(toDoItem.getDate()) to get date and time String

    final TextView dateView = itemLayout.findViewById(R.id.dateView);
            dateView.setText(ToDoItem.FORMAT);

    // Return the View you just created
    return itemLayout;

}

private void log(String msg) {
    try {
        Thread.sleep(500);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    Log.i(TAG, msg);
}

}

这是第四个 Activity ToDoManagerActivity

package course.labs.todomanager;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.text.ParseException;
import java.util.Date;

import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;
import course.labs.todomanager.ToDoItem.Priority;
import course.labs.todomanager.ToDoItem.Status;

public class ToDoManagerActivity extends ListActivity {

// Add a ToDoItem Request Code
private static final int ADD_TODO_ITEM_REQUEST = 0;

private static final String FILE_NAME = "TodoManagerActivityData.txt";
private static final String TAG = "Lab-UserInterface";

// IDs for menu items
private static final int MENU_DELETE = Menu.FIRST;
private static final int MENU_DUMP = Menu.FIRST + 1;

ToDoListAdapter mAdapter;

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

    // Create a new TodoListAdapter for this ListActivity's ListView
    mAdapter = new ToDoListAdapter(getApplicationContext());

    // Put divider between ToDoItems and FooterView
    getListView().setFooterDividersEnabled(true);

    //TODO - Inflate footerView for footer_view.xml file

    TextView footerView = TextView().getLayoutInflater()
        .inflate(R.layout.footer_view, null);

    //TODO - Add footerView to ListView
    getListView fv = (ListView)findViewById(R.layout.footer_view);
    
    footerView.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {

            log("Entered footerView.OnClickListener.onClick()");

            //TODO - Attach Listener to FooterView. Implement onClick().
            Intent intent = new Intent(getBaseContext(), AddToDoActivity.class);
                    startActivityForResult(intent, ADD_TODO_ITEM_REQUEST);
        }
    });

    //TODO - Attach the adapter to this ListActivity's ListView
    getListView.footer_view.setAdapter(mAdapter, fv);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {

    log("Entered onActivityResult()");

    // TODO - Check result code and request code.
    // If user submitted a new ToDoItem
    // Create a new ToDoItem from the data Intent
    // and then add it to the adapter
    if requestCode == ADD_TODO_ITEM_REQUEST {
        also if resultCode != RESULT_OK(true);
        new mAdapter++;
        
    }
}

// Do not modify below here

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

    // Load saved ToDoItems, if necessary

    if (mAdapter.getCount() == 0)
        loadItems();
}

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

    // Save ToDoItems

    saveItems();

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    super.onCreateOptionsMenu(menu);

    menu.add(Menu.NONE, MENU_DELETE, Menu.NONE, "Delete all");
    menu.add(Menu.NONE, MENU_DUMP, Menu.NONE, "Dump to log");
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case MENU_DELETE:
        mAdapter.clear();
        return true;
    case MENU_DUMP:
        dump();
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

private void dump() {

    for (int i = 0; i < mAdapter.getCount(); i++) {
        String data = ((ToDoItem) mAdapter.getItem(i)).toLog();
        log("Item " + i + ": " + data.replace(ToDoItem.ITEM_SEP, ","));
    }

}

// Load stored ToDoItems
private void loadItems() {
    BufferedReader reader = null;
    try {
        FileInputStream fis = openFileInput(FILE_NAME);
        reader = new BufferedReader(new InputStreamReader(fis));

        String title = null;
        String priority = null;
        String status = null;
        Date date = null;

        while (null != (title = reader.readLine())) {
            priority = reader.readLine();
            status = reader.readLine();
            date = ToDoItem.FORMAT.parse(reader.readLine());
            mAdapter.add(new ToDoItem(title, Priority.valueOf(priority),
                    Status.valueOf(status), date));
        }

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (ParseException e) {
        e.printStackTrace();
    } finally {
        if (null != reader) {
            try {
                reader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

// Save ToDoItems to file
private void saveItems() {
    PrintWriter writer = null;
    try {
        FileOutputStream fos = openFileOutput(FILE_NAME, MODE_PRIVATE);
        writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(
                fos)));

        for (int idx = 0; idx < mAdapter.getCount(); idx++) {

            writer.println(mAdapter.getItem(idx));

        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (null != writer) {
            writer.close();
        }
    }
}

private void log(String msg) {
    try {
        Thread.sleep(500);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    Log.i(TAG, msg);
}

}

有没有想过如何改进 AddToDoAcitivity 中的 cancelButton 代码？

final Button cancelButton = (Button) findViewById(R.id.cancelButton);
cancelButton.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        log("Entered cancelButton.OnClickListener.onClick()");

        //TODO - Implement onClick().  
        Intent intent = new Intent setResult;
        finish();
        
    }
});