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  1. #21
    jaymaan is offline Member
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    Default Re: New to Java and Java Forums - need help.

    Hi there,

    I couldnt figure how stringBuilder works, however I tried something new to the code like below. It does read all the file but each line in each dialog box.
    How can I fit all lines in one dialog box?

    Java Code:
    import java.io.File;
    import java.util.Scanner;
    import javax.swing.JOptionPane;
    
    
    public class readfile 
    {
    	private Scanner s;
    	
    	public void openFile() {
    	try{
    	s = new Scanner(new File("carsDB.csv"));
    	}
    	catch (Exception e){
    		JOptionPane.showMessageDialog(null,"File not found!");
    		}
    	}
    	
    	public void readFile(){
    		
    		while(s.hasNextLine()){
    			String a = s.nextLine();
    			
    			JOptionPane.showMessageDialog(null,"Following cars are currently available:-\n"
    										+ a, "Car Database",JOptionPane.INFORMATION_MESSAGE);
    		}
    	}
    	public void closeFile(){
    		s.close();
    	}
    }

  2. #22
    Tolls is offline Moderator
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    Default Re: New to Java and Java Forums - need help.

    What do you not understand about StringBuilder?
    Please do not ask for code as refusal often offends.

    ** This space for rent **

  3. #23
    jaymaan is offline Member
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    Default Re: New to Java and Java Forums - need help.

    Hi, im not familiar with StringBuilder...anyways I have managed to get what output I wish by changing the code as below

    Java Code:
    public void readFile() {
    		
    		String a = "";
    		
    		while (s.hasNextLine()) {
    			
    			a += s.nextLine() + "\n";
    		}
    		
    		JOptionPane.showMessageDialog(null,
    				"Following cars are currently available:-\n" + a,
    				"Car Database", JOptionPane.INFORMATION_MESSAGE);
    	}
    
    	public void closeFile() {
    		s.close();
    	}

  4. #24
    jaymaan is offline Member
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    Default Re: New to Java and Java Forums - need help.

    I got another issue.....

    I can read my .csv file perfectly but if I want to make a dropdown menu out of the file....all 5 lines are shown in one single line.

    How can use .split to split the lines at every third comma "," ???

    Java Code:
    import java.io.File;
    import java.util.Scanner;
    
    import javax.swing.JOptionPane;
    
    
    public class deleteline {
    
    	private Scanner s;
    
    	public void openFile() {
    		try {
    			s = new Scanner(new File("carsDB.csv"));
    		} catch (Exception e) {
    			JOptionPane.showMessageDialog(null, "File not found!");
    		}
    	}
    
    	public void readFile() {
    		
    		String a = "";
    		
    		while (s.hasNextLine()) {
    			a += s.nextLine() + "\n";
    		}
    		
    		String menu [] = a.split(" ,");
    		Object[] selectionValues = menu;
    
    		String initialSelection = "Please select";
    		
    		Object selection = JOptionPane.showInputDialog(null,
    				"Please select option.", "Cars Database Menu",
    				JOptionPane.QUESTION_MESSAGE, null, selectionValues,
    				initialSelection);
    
    		JOptionPane.showMessageDialog(null, "You have choosen to "
    				+ selection + ".", "Cars Database Menu",
    				JOptionPane.INFORMATION_MESSAGE);
    		
    		JOptionPane.showMessageDialog(null,
    				"Following cars are currently available:-\n" + a,
    				"Car Database", JOptionPane.INFORMATION_MESSAGE);
    	}
    
    	public void closeFile() {
    		s.close();
    	}
    }

  5. #25
    jaymaan is offline Member
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    Default Re: New to Java and Java Forums - need help.

    Hi Tol

    I have worked around and got it right.

    As per the program, I need to delete the specific row. I have String a where the file is as the database. I have to remove the selected row from String a and write it back to the csv file.

    I cant figure how to remove this specific row. Below is so far I have reached and stuck for now.

    Java Code:
    public class deleteline {
    
    	private Scanner s;
    
    	public void openFile() {
    		try {
    			s = new Scanner(new File("carsDB.csv"));
    		} catch (Exception e) {
    			JOptionPane.showMessageDialog(null, "File not found!");
    		}
    	}
    	
    	public void readFile() throws IOException {
    		
    		String a = "";
    		
    		while (s.hasNextLine()) {
    			a += s.nextLine() + "\n";
    		}
    		
    		String menu [] = a.split("\n");
    		Object[] selectionValues = menu;
    		String initialSelection = "Please select";
    		
    		Object selection = JOptionPane.showInputDialog(null,
    				"Please select option.", "Cars Database Menu",
    				JOptionPane.QUESTION_MESSAGE, null, selectionValues,
    				initialSelection);
    
    		JOptionPane.showMessageDialog(null, "You have choosen to delete "
    				+ selection + ".", "Cars Database Menu",
    				JOptionPane.INFORMATION_MESSAGE);
    		
    		if(selection.equals(selection)){
    			String remove = selection.toString();
    			a.matches(remove);
    			//how do I delete this row which matches?
    		}
    	}
    	
    	public void closeFile() {
    		s.close();
    	}
    }
    New to Java and Java Forums - need help.-screen-shot-2013-02-05-3.13.13-pm.png
    New to Java and Java Forums - need help.-screen-shot-2013-02-05-3.13.30-pm.png

  6. #26
    Tolls is offline Moderator
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    Default Re: New to Java and Java Forums - need help.

    You have to rewrite the file.
    One method is to write out the csv data to a temp file, skipping the line to delete, then remove the original file, finally rename the temp file.
    Please do not ask for code as refusal often offends.

    ** This space for rent **

  7. #27
    jaymaan is offline Member
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    Default Re: New to Java and Java Forums - need help.

    Hi

    I do understand the process in theory. I dont know how to write the same file with skipping the row to delete.


  8. #28
    Tolls is offline Moderator
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    Default Re: New to Java and Java Forums - need help.

    You know the row, surely?
    At least you can find it because you have the text for it.
    Please do not ask for code as refusal often offends.

    ** This space for rent **

  9. #29
    jaymaan is offline Member
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    Default Re: New to Java and Java Forums - need help.

    Thank you Guys, I have almost completed my program. Learned a lot during this. Thanks once again.

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