Latest topics for the forum "New to Java"

Help opening Java

kieran_je — GMT

hi, I'm having problems opening Java, i'm not programming or anything like that, just managing a device that runs java i think, when i click the link in a web browser i get could not find main class: Settings/Temp/kieran.ord_emlFwk/policy_emlfw. Program will exit? I've tried uninstalling different versions and nothing works?

indexOf for finding space

Kirra — GMT

help please :) just starting java now and trying to find a space in a string, but it return error -1

[i][color=darkblue]package substringmethod;
import java.util.Scanner;

public class Substringmethod {

public static void main(String[] args) {
Scanner user_input = new Scanner(System.in);
String nameChars;
String fullName;

System.out.println("Enter your name:");
fullName = user_input.next();

nameChars = fullName.substring(0,2);
//System.out.println(nameChars); [/color]

[color=red] int result = fullName.indexOf(" ");
System.out.println("Space is at post: "+result);[/color]
[color=darkblue] }
} [/color] [/i]

What am I doing wrong :(

output of a program

puja219 — GMT

public static void main(String ars[])
{
String text="cOmpUtEr",st=" ";
for(int i=0;i
{
if(Character.isLowerCase(text.charAt(i)))
st+=Character.toUpperCase(text.charAt(i));
elseif(Character.isUpperCase(text.char(i)));
if(i%2!=0)
st+=Character.toLowerCase(text.charAt(i));
else
st=text.charAt(i-1);
}
System.out.println(st);
}

Sorting algorithm java confusion! Help please!

benisjammin208 — GMT

Hi! In our java class we're doing sorting algorithms.. Now in all honestly I'am confused as hell about these things! I'll paste the code im looking at and if someone would please explain to me how the program is swapping array data that would be great! Thanks!

import java.util.Scanner;

public class inThirdPlace
{

public static void main(String[] args) {
int[] grades = new int[5];
System.out.println("Please enter " + grades.length + " grades...");
input(grades);
System.out.println("Original data:");
output(grades);
System.out.println("Just doing a selection sort...");
sort(grades);
System.out.println("Sorfted data:");
output(grades);
}

public static void input(int[] arr)
{
Scanner scanner = new Scanner(System.in);

for (int i = 0; i < arr.length; i++)
{
System.out.print("Please enter " + (i + 1) + " of " + arr.length + ": ");
arr[i] = scanner.nextInt();
}

// Make scanner
// Ask for candiate
// While input not -1
// arr[input - 1]++;
// Ask for candiate
}

public static void sort(int[] arr)
{
for (int pass = 1; pass < arr.length; pass++)
{
int largestPos = findLargest(arr, arr.length - pass);
if (largestPos != arr.length - pass)
{
swap(arr, largestPos, arr.length - pass);
}
//output(arr); //this is for testing purposes only
}
}

public static int findLargest(int [] arr, int num)
{
int largestPos = 0;
for (int i = 1; i <= num; i++)
{
if (arr[i] > arr[largestPos])
{
largestPos = i;
}
}
return largestPos;
}

public static void swap(int [] arr, int first, int second)
{
int temp = arr[first];
arr[first] = arr[second];
arr[second] = temp;
}

public static void output(int[] arr)
{
for (int i = 0; i < arr.length; i++)
{
System.out.print("arr[" + i + "] = " + arr[i] + ", ");
}
System.out.println();
}
}

Sorting 2-D Loops

joecartoonfn — GMT

Hello, I'm fairly new at java and cant seem to figure out this fairly simple exercise. I need a method that should pretty much first sort the order of the sub arrays by the rows in least to greatest. For example {{4, 7}, {2, 1}, {1, 3}, {4, 3}, {1, 1}} might be sorted to {{1, 3}, {1, 1}, {2, 1}, {4, 7}, {4, 3}}. The next step is sorting the resulting array by columns from least to greatest. So the resulting array after this would be {{1, 1}, {1, 3}, {2, 1}, {4, 3}, {4, 7}}. Please let me know if this is making sense.

Project help!

ben6 — GMT

[b]Please if anyone could help be greatly appreciated![/b]

Brief
Read in a word and display if the letters are in ascending order or not in ascending order. Ignore letter case in your comparison.

Example input data Commentary
almost Line 1
effort Line 2
end Line 3
knotty
known
END Terminator

Expected output

Almost letters in ascending order
Effort letters in ascending order
End letters not in ascending order
Knotty letters in ascending order
Known letters not in ascending order

Remember to submit the whole application which must have the class name Main.
Remember any line printed that contains a # will not be considered as part of your answer.
This is so that you can write out a meaningful prompt for any data (containing a # character) and this line of text will be ignored in the comparison of your answer.
If the String variable name holds the character string END then name.equals("END") will return true. [b]

Map a Network Drive Using Java

itgeek25 — GMT

I have a project that I am working on. One of the items is to see if I can get Java to map a network drive. It is not working. I am using JOptionPane to ask the user for information to input to get the proper command. The variables just keep passing through as null. I can't seem to get it to work. Below is the code. Any suggestions would be great.

BTW, I have tried Runtime.getRuntime().exec() in a few different various. Am I correct in pursuing this API or should I use another? I just read about JCIFS. Thought this may work but seems it is used for accessing file shares, not actually mapping a local drive.

[code]
try {
JOptionPane.showInputDialog(null, "What drive letter do you want to give the new drive?", host);
JOptionPane.showInputDialog(null, "What shared item do you want to map to your drive?", path);
JOptionPane.showInputDialog(null, "What user has the approriate permissions to this share?", user);
JOptionPane.showInputDialog(null, "What is the password for this user account?", password);
String s = "cmd.exe /K START C:\\Windows\\system32\\net.exe use " + host + ":" + " " + path + " /user:" + user + " " + password;
String command = "cmd.exe /K net use";
Process p2 = Runtime.getRuntime().exec(s);
Process p = Runtime.getRuntime().exec(command);
System.out.println( s );
}
catch (IOException e) {
System.out.println("exception happened");
e.printStackTrace();
}
[/code]

I require some assistance with my conversion program.

sublime303 — GMT

nevermind, thanks

FileDialog and FileReader

itgeek25 — GMT

I am looking for a little bit of guidance. I am new to Java. I set up a program to use the FileDialog to allow a user to select and open a text document but when they do, the text of the document doesn't appear in the textarea.

I have done this with FileChooser and FileInputStream and it works fine. From what I am getting is that FileInputStream doesn't "play nice" with FileDialog. Am I correct in trying to work with FileReader to print the text. I have a piece of some code listed below of something similar that I am trying to do but just a little smaller and printing text to the console. Same idea.

Thanks in advance.

[code]
import java.awt.FileDialog;
import java.awt.Frame;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import javax.swing.JFrame;

import javax.swing.JFileChooser;

public class testFileDialog extends Frame {
static Frame frame;
/**
* @param args
* @param frame
* @throws FileNotFoundException
*/
public static void main(String[] args) throws IOException {

FileDialog chooser;
String homedir;
homedir = System.getProperty("user.home");
chooser= new FileDialog( frame );
chooser.setLocationRelativeTo( null );
chooser.setLocation( 200, 200 );
chooser.setDirectory(System.getProperty(homedir));
chooser.setVisible( true );

FileReader something = new FileReader(chooser.getFile());
System.out.println(something);
}
}

Trying to get class information without opening a new window

itgeek25 — GMT

I am trying to configure a open dialog box with a class name OpenBox to open a text file and input the information into a textarea in another class file, classA. I have everything working except that the OpenBox class is opening the file I select with into a new window. I would like to get it to open the file and input the information into the original classA textarea.

BTW, this program is just a look a like of a Notepad.exe application. This is just for learning Java functions and features.

I get get it to work if I create the OpenBox class public inside the classA Java class. I would like to keep them in seperate Java classes.

I DO understand my syntax errors and I have an idea of what it should be but I keep getting errors. I have tried Abstract Actions too but they don't work. Any suggestions would be great. Forgive me i this is a "silly" questions. I am trying to teach myself as a go along with Java. Still a newbie to Java. Thanks in advanced.

The problem is lines 100-102 in classA and line 30 in OpenBox.

Java class classA

[code]
public class classA extends JFrame {

JTextArea textarea1;

JMenu file = new JMenu("File");
JMenu edit = new JMenu("Edit");
JMenu format = new JMenu("Format");
JMenu view = new JMenu("View");
JMenu help = new JMenu("Help");
JMenuItem new1 = new JMenuItem("New Ctrl + N");
JMenuItem open = new JMenuItem("Open Ctrl + O");
JMenuItem save = new JMenuItem("Save Ctrl + S");
JMenuItem save1 = new JMenuItem("Save As... ");
JMenuItem exit = new JMenuItem("Exit ");
JMenuBar menubar = new JMenuBar();

Event op = new Event();
//ends

public classA() {

textarea1 = new JTextArea(5, 30);
add(textarea1);

//add local string
String grab = "Grab this\n";
insert(grab, 1);
//end local string

setSize(500, 500);
setVisible(true);

//start

setJMenuBar(menubar);
menubar.add(file);
menubar.add(edit);
menubar.add(format);
menubar.add(view);
menubar.add(help);
file.add(new1);

//create list item in file and add event handler to it
file.add(open);
open.addActionListener(op);

//create save function
file.add(save);

//create save as event handler
file.add(save1);
//save1.addActionListener(sva);

//create list item in file and add event handler to it
file.add(exit);
//exit.addActionListener(ex);
//ends

//adds a scroll bar to textarea
JScrollPane scrollPane = new JScrollPane(textarea1);
setPreferredSize(new Dimension(450, 110));
add(scrollPane, BorderLayout.CENTER);

}

//this for a local insert of text
private void insert(String grab, int i) {
// TODO Auto-generated method stub
textarea1.insert(grab, 1);
}
//end local

public void add(Component stuff, Component stuff2, Component button1) {
// TODO Auto-generated method stub
textarea1.add( stuff );
textarea1.add( stuff2 );
textarea1.add( button1 );
}

public class Event implements ActionListener {

public void actionPerformed(ActionEvent op) {

OpenBox ope = new OpenBox();

}
}

public static void main(String[] args) {
classA classes = new classA();
}

public void add(String str, String str2) {
// TODO Auto-generated method stub
textarea1.insert(str, 1);
textarea1.insert(str2, 1);
}

//added to grab variables from OpenBox
public void read(BufferedReader br, String strLine) throws IOException {
// TODO Auto-generated method stub
textarea1.read(br, strLine);
}

}
[/code]

Java class OpenBox
[code]
public class OpenBox extends JFrame {

public OpenBox() {

super();

classA textarea1 = new classA();

//create function method to open a file, this opens a window pane to search for file
String wd = System.getProperty(".");
JFileChooser fc = new JFileChooser(wd);
int rc = fc.showDialog(null, "Select Data File");
if (rc == JFileChooser.APPROVE_OPTION)
{
File file = fc.getSelectedFile();
String filename = file.getAbsolutePath();

//This is the action we are performing when we select the file, it will print out in the console
System.out.println(filename);
try {
FileInputStream fstream = new FileInputStream (file);
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strLine;
while ((strLine = br.readLine()) != null) {
System.out.println(strLine);

//adds file output text to JTextArea
FileOutputStream out = new FileOutputStream(strLine);
textarea1.read(br, strLine);
//ends file output text
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

//end
}
}

/**
* @param args
* @param br
* @param strLine
* @param
* @param
* @throws IOException
*/
public static void main(String[] args) {
// TODO Auto-generated method stub

}

}
[/code]

Add Text from one class to another class

itgeek25 — GMT

What I am trying to do is use a JTextArea from one class file in another class file for easy code administration. I am using it for a few different projects and my latests is to add a Open Dialog box and a Save as dialog box. Everything is working fine but getting or adding text to a JTextArea from another class file.

I can get it to work fine if I keep everything in the same class file, but I really would like to split it up so it is easier to read. Similar to a webpage with PHP include statements.

This may seem like a simple question but I can't figure it out. I have looked all over the internet and still can't find an answer. I have tried many things and it's just not working. A little insight would be appreciated. Thanks in advance. Below is just a sample of what I am trying to do.

I would like the JTextField to print the text from classB to the JTextArea in classA.

The first file has this in it:

import javax.swing.*;

public class classA extends JFrame {

JTextArea textarea1;

public classA() {
textarea1 = new JTextArea(5, 30);
add(textarea1);
setSize(200, 200);
setVisible(true);
}

public static void main(String[] args) {
classA classes = new classA();
}
}

The second class file has this in it:

import javax.swing.*;

public class classB extends JFrame {

public static void main(String[] args) {

classA method = new classA();

JTextField fields = new JTextField("Stuff");
//trying to add this to the content of textarea1
method.textarea1.add(fields);
}
}

Hi new to java trying to do something new :) any help would be appreciated!

garethnicoos — GMT

hi, I am trying to complete the following task (purely for fun) I would really appreciate it if someone could adapt my code:

Write an a Java application which prints a diamond in a
square grid of dots whose side length is input to the
application. The side of the square must be an odd
number. If the input data is invalid an error message is
output. For example, if the input data was 10 then the
error message
Size (10) invalid must be odd
would be printed. If the input data was -5 then the error
message
Sides of square must be positive
would be printed

Here is my code i have got:
public class Stars
{
public static void main(String[] args)
{
System.out.println("Enter size of Diamond");

System.out.println();
int longestRow = BIO.getInt();

for(int row=1 ; row<=longestRow ; ++row)
{
int i = (2*row) - 1;
if(i>longestRow) i = 2*(longestRow-row+1) - 1;
for(int j=0 ; j<(longestRow-i)/2 ; ++j) System.out.print(".");
for(int j=0 ; j
for(int j=0 ; j<(longestRow-i)/2 ; ++j) System.out.print(".");
System.out.println();
}
}
}

this looks like this when ran:
5
..*..
.***.
*****
.***.
..*..

I am trying to make it look like this:
..*..
.*.*.
*...*
.*.*.
..*..

Thanks Gareth

Help, I have no idea what the console is telling me.

Zack22 — GMT
I'm using Windows XP and Java is up to date and all older versions are uninstalled, first off.

I use a Java Based chat room and have been without issue for some time now and now when it tries to load, I get an error message and this in the console.

load: class com.chatspace.v400320.Chat not found.
java.lang.ClassNotFoundException: com.chatspace.v400320.Chat
at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception: java.lang.ClassNotFoundException: com.chatspace.v400320.Chat

Is this problem on my end or their end?

Tic tac toe help

hayden11 — GMT
I am having issues with this code. First when I try to play it, the char (either X or O) doesn't show up, just squares do. Then secondly, I want to incorperate a grid like this

1 : 2 : 3
--+--+--
4 : 5 : 6
--+--+--
7 : 8 : 9

please tell me what I need to do, thanks. - Newb

Help Breaking down some java code

scoobz1234 — GMT
Hello, i am in need of some help to break down this code and to maybe tell me how it works. the code i am trying to work with /change is a skybox background of sorts. its a panorama background on a java client. i want to change it to a single background layer one image no movement. below is the code.

[code] private void func_35355_b(int i, int j, float f)
{
Tessellator tessellator = Tessellator.instance;
GL11.glMatrixMode(5889 /*GL_PROJECTION*/);
GL11.glPushMatrix();
GL11.glLoadIdentity();
GLU.gluPerspective(120F, 1.0F, 0.05F, 10F);
GL11.glMatrixMode(5888 /*GL_MODELVIEW0_ARB*/);
GL11.glPushMatrix();
GL11.glLoadIdentity();
GL11.glColor4f(1.0F, 1.0F, 1.0F, 1.0F);
GL11.glRotatef(180F, 1.0F, 0.0F, 0.0F);
GL11.glEnable(3042 /*GL_BLEND*/);
GL11.glDisable(3008 /*GL_ALPHA_TEST*/);
GL11.glDisable(2884 /*GL_CULL_FACE*/);
GL11.glDepthMask(false);
GL11.glBlendFunc(770, 771);
int k = 8;
for(int l = 0; l < k * k; l++)
{
GL11.glPushMatrix();
float f1 = ((float)(l % k) / (float)k - 0.5F) / 64F;
float f2 = ((float)(l / k) / (float)k - 0.5F) / 64F;
float f3 = 0.0F;
GL11.glTranslatef(f1, f2, f3);
GL11.glRotatef(MathHelper.sin(((float)field_35357_f + f) / 400F) * 25F + 20F, 1.0F, 0.0F, 0.0F);
GL11.glRotatef(-((float)field_35357_f + f) * 0.1F, 0.0F, 1.0F, 0.0F);
for(int i1 = 0; i1 < 6; i1++)
{
GL11.glPushMatrix();
if(i1 == 1)
{
GL11.glRotatef(90F, 0.0F, 1.0F, 0.0F);
}
if(i1 == 2)
{
GL11.glRotatef(180F, 0.0F, 1.0F, 0.0F);
}
if(i1 == 3)
{
GL11.glRotatef(-90F, 0.0F, 1.0F, 0.0F);
}
if(i1 == 4)
{
GL11.glRotatef(90F, 1.0F, 0.0F, 0.0F);
}
if(i1 == 5)
{
GL11.glRotatef(-90F, 1.0F, 0.0F, 0.0F);
}
GL11.glBindTexture(3553 /*GL_TEXTURE_2D*/, mc.renderEngine.getTexture((new StringBuilder()).append("/title/bg/panorama").append(i1).append(".png").toString()));
tessellator.startDrawingQuads();
tessellator.setColorRGBA_I(0xffffff, 255 / (l + 1));
float f4 = 0.0F;
tessellator.addVertexWithUV(-1D, -1D, 1.0D, 0.0F + f4, 0.0F + f4);
tessellator.addVertexWithUV(1.0D, -1D, 1.0D, 1.0F - f4, 0.0F + f4);
tessellator.addVertexWithUV(1.0D, 1.0D, 1.0D, 1.0F - f4, 1.0F - f4);
tessellator.addVertexWithUV(-1D, 1.0D, 1.0D, 0.0F + f4, 1.0F - f4);
tessellator.draw();
GL11.glPopMatrix();
}

GL11.glPopMatrix();
GL11.glColorMask(true, true, true, false);
}

tessellator.setTranslationD(0.0D, 0.0D, 0.0D);
GL11.glColorMask(true, true, true, true);
GL11.glMatrixMode(5889 /*GL_PROJECTION*/);
GL11.glPopMatrix();
GL11.glMatrixMode(5888 /*GL_MODELVIEW0_ARB*/);
GL11.glPopMatrix();
GL11.glDepthMask(true);
GL11.glEnable(2884 /*GL_CULL_FACE*/);
GL11.glEnable(3008 /*GL_ALPHA_TEST*/);
GL11.glEnable(2929 /*GL_DEPTH_TEST*/);
}

private void func_35354_a(float f)
{
GL11.glBindTexture(3553 /*GL_TEXTURE_2D*/, viewportTexture);
GL11.glCopyTexSubImage2D(3553 /*GL_TEXTURE_2D*/, 0, 0, 0, 0, 0, 256, 256);
GL11.glEnable(3042 /*GL_BLEND*/);
GL11.glBlendFunc(770, 771);
GL11.glColorMask(true, true, true, false);
Tessellator tessellator = Tessellator.instance;
tessellator.startDrawingQuads();
byte byte0 = 3;
for(int i = 0; i < byte0; i++)
{
tessellator.setColorRGBA_F(1.0F, 1.0F, 1.0F, 1.0F / (float)(i + 1));
int j = width;
int k = height;
float f1 = (float)(i - byte0 / 2) / 256F;
tessellator.addVertexWithUV(j, k, zLevel, 0.0F + f1, 0.0D);
tessellator.addVertexWithUV(j, 0.0D, zLevel, 1.0F + f1, 0.0D);
tessellator.addVertexWithUV(0.0D, 0.0D, zLevel, 1.0F + f1, 1.0D);
tessellator.addVertexWithUV(0.0D, k, zLevel, 0.0F + f1, 1.0D);
}

tessellator.draw();
GL11.glColorMask(true, true, true, true);
}

private void func_35356_c(int i, int j, float f)
{
GL11.glViewport(0, 0, 256, 256);
func_35355_b(i, j, f);
func_35354_a(f);
func_35354_a(f);
func_35354_a(f);
func_35354_a(f);
func_35354_a(f);
func_35354_a(f);
func_35354_a(f);
func_35354_a(f);
GL11.glViewport(0, 0, mc.displayWidth, mc.displayHeight);
Tessellator tessellator = Tessellator.instance;
tessellator.startDrawingQuads();
float f1 = width <= height ? 120F / (float)height : 120F / (float)width;
float f2 = ((float)height * f1) / 256F;
float f3 = ((float)width * f1) / 256F;
GL11.glTexParameteri(3553 /*GL_TEXTURE_2D*/, 10241 /*GL_TEXTURE_MIN_FILTER*/, 9729 /*GL_LINEAR*/);
GL11.glTexParameteri(3553 /*GL_TEXTURE_2D*/, 10240 /*GL_TEXTURE_MAG_FILTER*/, 9729 /*GL_LINEAR*/);
tessellator.setColorRGBA_F(1.0F, 1.0F, 1.0F, 1.0F);
int k = width;
int l = height;
tessellator.addVertexWithUV(0.0D, l, zLevel, 0.5F - f2, 0.5F + f3);
tessellator.addVertexWithUV(k, l, zLevel, 0.5F - f2, 0.5F - f3);
tessellator.addVertexWithUV(k, 0.0D, zLevel, 0.5F + f2, 0.5F - f3);
tessellator.addVertexWithUV(0.0D, 0.0D, zLevel, 0.5F + f2, 0.5F + f3);
tessellator.draw();
}[/code]

Thanks in advance for any help you have to offer!!