Search in the array

[ŖàΫ ỏƒ Ңόρę]

Hi

The following code is a simple example for using GUI to enter the ID number then determines whether the number is right or not.

When I enter one of the three numbers that I wrote in the array, it gives me the correct message but if I enter any wrong number it will stop the program.

import javax.swing.*;

import java.awt.*;
import java.awt.event.*;
import java.text.DateFormat;
import java.util.Date;
import java.util.Locale;

public class Management extends JApplet implements ActionListener{
	
	private JLabel label;
	private JLabel labelDate;
	private JButton button;
	private static Locale alocal;
	private static Date today;
	private static String dateOut;
	private static DateFormat dateFormatter;
	private int[] ID={1213,3343,7604};
	
	public boolean binarySearch(int obj){
		int i=0;
		boolean val;
	
			
		while(obj!=ID[i] && i<ID.length){
			i++;
	}
			
			if(obj==ID[i]){
			val = true;
			}else{
				
				val = false;
			}
		return val;
	}
	
	public void init(){
		
		alocal  = new Locale("CANADA");
		dateFormatter = DateFormat.getDateInstance(DateFormat.DEFAULT,
				alocal);
		today = new Date();
		dateOut = dateFormatter.format(today);
		
		label = new JLabel("Welcome in Management Programe");
		button = new JButton("Entrance Panel");
		labelDate = new JLabel("");
		labelDate.setText(dateOut);
		
		button.addActionListener(this);
		
		
		Container contentPane = getContentPane();
		contentPane.setLayout(new FlowLayout());
		contentPane.add(label);
		contentPane.add(labelDate);
		contentPane.add(button);
		
		
			
			
	}
	
	public void actionPerformed(ActionEvent eve){
		
		String str = JOptionPane.showInputDialog(getContentPane(), "Enter your ID number");
		int str1 = Integer.parseInt(str);
		int i=0;
		
		if(binarySearch(str1)==true){
			JOptionPane.showMessageDialog(getContentPane(), "Welcome Mr.NsNs");
			i++;
		}else{
			JOptionPane.showMessageDialog(getContentPane(), "Error");
			//JOptionPane.showMessageDialog(getContentPane(), "Invalid Name !!","Error" ,JOptionPane.ERROR_MESSAGE);
		}
	}
}

[JosAH]

	public boolean binarySearch(int obj){
		int i=0;
		boolean val;
	
			
		while(obj!=ID[i] && i<ID.length){
			i++;
	}
			
			if(obj==ID[i]){
			val = true;
			}else{
				
				val = false;
			}
		return val;
	}

Your an my definition for 'binary search' are quite different. Hint: what happens when ID[0] is the wanted ID? Your seach method won't find it and throws an ArrayIndexOutOfBounds exception ... IOW that method stinks.

kind regards,

Jos

[PhHein]

It doesn't stop the program, you get an exception. Your binarySearch method is seriously borked.

EDIT: what Jos said.

[ŖàΫ ỏƒ Ңόρę]

I finally solved it.

the first problem was in this line

while( i<ID.length &&  obj!=ID[i]){

I exchange obj!=ID[i] with i<ID.length.

the second one

if(ID[i]==obj){

the problem with i ( if i = 3)
in this case I added

if(i==ID.length){
				i = i -1;
			}

[JosAH]

I finally solved it.

the first problem was in this line

while( i<ID.length &&  obj!=ID[i]){

I exchange obj!=ID[i] with i<ID.length.

the second one

if(ID[i]==obj){

the problem with i ( if i = 3)
in this case I added

if(i==ID.length){
				i = i -1;
			}

That's a very elaborate way to say just this:

for (int i= 0; i < ID.length; i++)
   if (ID[i] == obj)
      return i;
return -1; // not found value

kind regards,

Jos