CSE 292 Java ProgrammingProfessor Tong Lai Yu
Homework 5Santiago Campero
1) Follow the tutorial of the link,
http://developer.android.com/resources/tutorials/views/hello-gridview.html to create the Grid View of the HelloWorld example in Android. Replace some of the icons provided by the site by your own icons. Choose Android version 2.3.3.
Program Run
ImageAdapter.Java
package com.example.hellogridview;import android.content.Context;import android.view.View;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.GridView;import android.view.ViewGroup;public class ImageAdapter extends BaseAdapter { private Context mContext;
public ImageAdapter(Context c) { mContext = c; } public int getCount() { return mThumbIds.length; } public Object getItem(int position) { return null; } public long getItemId(int position) { return 0; } // create a new ImageView for each item referenced by the Adapter public View getView(int position, View convertView, ViewGroup parent) { ImageView imageView; if (convertView == null) { // if it's not recycled, initialize some attributes imageView = new ImageView(mContext); imageView.setLayoutParams(new GridView.LayoutParams(85, 85)); imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); imageView.setPadding(8, 8, 8, 8); } else { imageView = (ImageView) convertView; } imageView.setImageResource(mThumbIds[position]); return imageView; } // references to our images private Integer[] mThumbIds = { R.drawable.sample_2, R.drawable.sample_3, R.drawable.sample_4, R.drawable.sample_5, R.drawable.sample_6, R.drawable.sample_7, R.drawable.sample_0, R.drawable.sample_1, R.drawable.sample_2, R.drawable.sample_3, R.drawable.sample_4, R.drawable.sample_5, R.drawable.sample_6, R.drawable.sample_7, R.drawable.sample_0, R.drawable.sample_1, R.drawable.sample_2, R.drawable.sample_3, R.drawable.sample_4, R.drawable.sample_5, R.drawable.sample_6, R.drawable.sample_7 };}
MainActivity.Java
package com.example.hellogridview;
import android.os.Bundle;import android.app.Activity;import android.widget.AdapterView;import android.widget.AdapterView.OnItemClickListener;import android.widget.GridView;import android.widget.Toast;import android.view.*;
public class MainActivity extends Activity {
@Overridepublic void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main);
GridView gridview = (GridView) findViewById(R.id.gridview); gridview.setAdapter(new ImageAdapter(this));
gridview.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View v, int position, long id)
{ Toast.makeText(MainActivity.this, "" + position,
Toast.LENGTH_SHORT).show(); } });}
}
Main.XML
<?xml version="1.0" encoding="utf-8"?><GridView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/gridview" android:layout_width="fill_parent" android:layout_height="fill_parent" android:columnWidth="90dp" android:numColumns="auto_fit" android:verticalSpacing="10dp" android:horizontalSpacing="10dp" android:stretchMode="columnWidth" android:gravity="center"/>
2) Follow the instructions of the following document, which is from your textbook,
Tip Calculator to create the Tip Calculator. The following is the source code of the problem:
TipCalculator.zip
Program Run
TipCalculator.Java
// TipCalculator.java// Calculates bills using 5, 10, 15 and custom percentage tips.
package com.deitel.tipcalculator;
import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TextView;
// main Activity class for the TipCalculator
public class TipCalculator extends Activity
{
// constants used when saving/restoring state
private static final String BILL_TOTAL = "BILL_TOTAL";
private static final String CUSTOM_PERCENT = "CUSTOM_PERCENT";
private double currentBillTotal; // bill amount entered by the user
private int currentCustomPercent; // tip % set with the SeekBar
private EditText tip10EditText; // displays 10% tip
private EditText total10EditText; // displays total with 10% tip
private EditText tip15EditText; // displays 15% tip
private EditText total15EditText; // displays total with 15% tip
private EditText billEditText; // accepts user input for bill total
private EditText tip20EditText; // displays 20% tip
private EditText total20EditText; // displays total with 20% tip
private TextView customTipTextView; // displays custom tip percentage
private EditText tipCustomEditText; // displays custom tip amount
private EditText totalCustomEditText; // displays total with custom tip
// Called when the activity is first created.
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState); // call superclass's version
setContentView(R.layout.main); // inflate the GUI
// check if app just started or is being restored from memory
if ( savedInstanceState == null ) // the app just started running
{
currentBillTotal = 0.0; // initialize the bill amount to zero
currentCustomPercent = 18; // initialize the custom tip to 18%
} // end if
else // app is being restored from memory, not executed from scratch
{
// initialize the bill amount to saved amount
currentBillTotal = savedInstanceState.getDouble(BILL_TOTAL);
// initialize the custom tip to saved tip percent
currentCustomPercent =
savedInstanceState.getInt(CUSTOM_PERCENT);
} // end else
// get references to the 10%, 15% and 20% tip and total EditTexts
tip10EditText = (EditText) findViewById(R.id.tip10EditText);
total10EditText = (EditText) findViewById(R.id.total10EditText);
tip15EditText = (EditText) findViewById(R.id.tip15EditText);
total15EditText = (EditText) findViewById(R.id.total15EditText);
tip20EditText = (EditText) findViewById(R.id.tip20EditText);
total20EditText = (EditText) findViewById(R.id.total20EditText);
// get the TextView displaying the custom tip percentage
customTipTextView = (TextView) findViewById(R.id.customTipTextView);
// get the custom tip and total EditTexts
tipCustomEditText = (EditText) findViewById(R.id.tipCustomEditText);
totalCustomEditText =
(EditText) findViewById(R.id.totalCustomEditText);
// get the billEditText
billEditText = (EditText) findViewById(R.id.billEditText);
// billEditTextWatcher handles billEditText's onTextChanged event
billEditText.addTextChangedListener(billEditTextWatcher);
// get the SeekBar used to set the custom tip amount
SeekBar customSeekBar = (SeekBar) findViewById(R.id.customSeekBar);
customSeekBar.setOnSeekBarChangeListener(customSeekBarListener);
} // end method onCreate
// updates 10, 15 and 20 percent tip EditTexts
private void updateStandard()
{
// calculate bill total with a ten percent tip
double tenPercentTip = currentBillTotal * .1;
double tenPercentTotal = currentBillTotal + tenPercentTip;
// set tipTenEditText's text to tenPercentTip
tip10EditText.setText(String.format("%.02f", tenPercentTip));
// set totalTenEditText's text to tenPercentTotal
total10EditText.setText(String.format("%.02f", tenPercentTotal));
// calculate bill total with a fifteen percent tip
double fifteenPercentTip = currentBillTotal * .15;
double fifteenPercentTotal = currentBillTotal + fifteenPercentTip;
// set tipFifteenEditText's text to fifteenPercentTip
tip15EditText.setText(String.format("%.02f", fifteenPercentTip));
// set totalFifteenEditText's text to fifteenPercentTotal
total15EditText.setText(
String.format("%.02f", fifteenPercentTotal));
// calculate bill total with a twenty percent tip
double twentyPercentTip = currentBillTotal * .20;
double twentyPercentTotal = currentBillTotal + twentyPercentTip;
// set tipTwentyEditText's text to twentyPercentTip
tip20EditText.setText(String.format("%.02f", twentyPercentTip));
// set totalTwentyEditText's text to twentyPercentTotal
total20EditText.setText(String.format("%.02f", twentyPercentTotal));
} // end method updateStandard
// updates the custom tip and total EditTexts
private void updateCustom()
{
// set customTipTextView's text to match the position of the SeekBar
customTipTextView.setText(currentCustomPercent + "%");
// calculate the custom tip amount
double customTipAmount =
currentBillTotal * currentCustomPercent * .01;
// calculate the total bill, including the custom tip
double customTotalAmount = currentBillTotal + customTipAmount;
// display the tip and total bill amounts
tipCustomEditText.setText(String.format("%.02f", customTipAmount));
totalCustomEditText.setText(
String.format("%.02f", customTotalAmount));
} // end method updateCustom
// save values of billEditText and customSeekBar
@Override
protected void onSaveInstanceState(Bundle outState)
{
super.onSaveInstanceState(outState);
outState.putDouble(BILL_TOTAL, currentBillTotal);
outState.putInt(CUSTOM_PERCENT, currentCustomPercent);
} // end method onSaveInstanceState
// called when the user changes the position of SeekBar
private OnSeekBarChangeListener customSeekBarListener =
new OnSeekBarChangeListener()
{
// update currentCustomPercent, then call updateCustom
@Override
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser)
{
// sets currentCustomPercent to position of the SeekBar's thumb
currentCustomPercent = seekBar.getProgress();
updateCustom(); // update EditTexts for custom tip and total
} // end method onProgressChanged
@Override
public void onStartTrackingTouch(SeekBar seekBar)
{
} // end method onStartTrackingTouch
@Override
public void onStopTrackingTouch(SeekBar seekBar)
{
} // end method onStopTrackingTouch
}; // end OnSeekBarChangeListener
// event-handling object that responds to billEditText's events
private TextWatcher billEditTextWatcher = new TextWatcher()
{
// called when the user enters a number
@Override
public void onTextChanged(CharSequence s, int start,
int before, int count)
{
// convert billEditText's text to a double
try
{
currentBillTotal = Double.parseDouble(s.toString());
} // end try
catch (NumberFormatException e)
{
currentBillTotal = 0.0; // default if an exception occurs
} // end catch
// update the standard and custom tip EditTexts
updateStandard(); // update the 10, 15 and 20% EditTexts
updateCustom(); // update the custom tip EditTexts
} // end method onTextChanged
@Override
public void afterTextChanged(Editable s)
{
} // end method afterTextChanged
@Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after)
{
} // end method beforeTextChanged
}; // end billEditTextWatcher
} // end class TipCalculator
3) The following are provided:• Lines.java • LinesJPanel
Follow the comments '/* .. */' to finish the programs.
Program Run
Lines.Java
package edu.CSE292.HW5c;
//Lab Exercise 2 Solution: Lines.java//This program draws lines of different colorsimport java.awt.Color;import javax.swing.JFrame;public class Lines{public static void main( String args[] ){ // create frame for LinesJPanel JFrame frame = new JFrame( "Lines" ); frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
LinesJPanel linesJPanel = new LinesJPanel(); frame.add( linesJPanel ); // add linesJPanel to frame frame.setSize( 300, 300 ); // set frame size frame.setVisible( true ); // display frame} // end main} // end class Lines
LinesJPanel.Java
package edu.CSE292.HW5c;
//Lab Exercise 2 Solution: LinesJPanel.java//This program draws lines of different colorsimport java.awt.Color;import java.awt.BasicStroke;import java.awt.geom.Line2D;import java.awt.Graphics;import java.awt.Graphics2D;import java.util.Random;import javax.swing.JPanel;
public class LinesJPanel extends JPanel {private Color colors[] = { Color.GREEN, Color.CYAN, Color.YELLOW, Color.DARK_GRAY, Color.RED, Color.ORANGE, Color.GRAY, Color.PINK, Color.MAGENTA };// create 10 linespublic void paintComponent( Graphics g ){ super.paintComponent( g ); setBackground( Color.BLACK ); // set JPanel background Random random = new Random(); // get random number generator int thickness = 1; // default thickness int colorChoice = 0; // default color green int lineLenght = 1; //default lenght // create 2D by casting g to Graphics 2D Graphics2D g2d = ( Graphics2D ) g; for ( int y = 60; y < 250; y += 20 ) { // choose a random color from array /* Randomly choose an element of array colors and pass it to Graphics2D method setColor to specify the drawing color */ //pickrandom integerfrom0to8 colorChoice = random.nextInt(8 ); g2d.setPaint(colors[colorChoice]); // choose a random thickness from 1-20 /* Use Graphics2D method setStroke to randomly set the thickness of a line */ //pickrandom integerfrom1to20 thickness = 1+random.nextInt(20 ); g2d.setStroke(new BasicStroke(thickness) ); // choose a random length and draw line /* Create a random length line and use Graphics2D method draw to display the lines*/ lineLenght = 1+random.nextInt(300 ); g2d.draw(new Line2D.Double(0, y, lineLenght, y ) ); } // end for} // end method paintComponent} // end class LinesJPanel
4) Textbook, P.763, #17.8 (Telephone Number Word Generation) Standard telephone keypads contain the digits zero through nine. The numbers two through nine each have three letters associated with them as shown below:
Digit Letter Digit Letter Digit Letter
2 A B C 5 J K L 8 T U V
3 D E F 6 M N O 9 W X Y
4 G H I 7 P R S
For ease of memorization, people develop seven-letter words that correspond to their phone numbers. For example, one might use NUMBERS to represent 686-2377.Every seven-letter phone number corresponds to many different seven-letter words, many of them unrecognizable. Write a program that, given a seven-digit number, uses a PrintStream object to write to a file every possible seven-letter word combination corresponding to that number. There are 2,187 (37 such combinations. Avoid phone numbers with digits 0 and 1.
Program Run
PhoneNames.Java
package edu.CSE292.HW5d;
//public class PhoneNames {
import java.util.LinkedList;import java.util.List;public class PhoneNames { // Number-to-letter mappings in order from zero to nine public static String mappings[][] = { {"0"}, {"1"}, {"A", "B", "C"}, {"D", "E", "F"}, {"G", "H", "I"}, {"J", "K", "L"}, {"M", "N", "O"}, {"P", "Q", "R", "S"}, {"T", "U", "V"}, {"W", "X", "Y", "Z"} }; public static void generateCombosHelper(List<String> combos, String prefix, String remaining) { // The current digit we are working with int digit = Integer.parseInt(remaining.substring(0, 1));
if (remaining.length() == 1) { // We have reached the last digit in the phone number, so add // all possible prefix-digit combinations to the list for (int i = 0; i < mappings[digit].length; i++) { combos.add(prefix + mappings[digit][i]); } } else { // Recursively call this method with each possible new // prefix and the remaining part of the phone number. for (int i = 0; i < mappings[digit].length; i++) { generateCombosHelper(combos, prefix + mappings[digit][i], remaining.substring(1)); } } } public static List<String> generateCombos(String phoneNumber) { // This will hold the final list of combinations List<String> combos = new LinkedList<String>();
// Call the helper method with an empty prefix and the entire // phone number as the remaining part. generateCombosHelper(combos, "", phoneNumber); return combos; } public static void main(String[] args) { String phone = "3456789"; List<String> combos = generateCombos(phone); for (String s : combos) { System.out.println(s); } }}
