How to use bubble sort in a java program?

[vishal1949]

I was writing a program that involves the console inputting integers and strings. For my project i prompt the user to enter the number of strings he would like. Then i prompt the user to enter the strings so i could order them alphabetically. I am supposed to use any sorting algorithm but since im new to programming i dont know any.

import java.io.*; 

public class Sorting
{
  private static BufferedReader stdin =  new BufferedReader( new InputStreamReader( System.in ) );

  public static void main(String[] arguments) throws IOException
  {
    System.out.println("How many strings would you like to enter?");
    int stringCount = Integer.parseInt(stdin.readLine());
    String[] stringInput = new String[stringCount];
    String message = "";
    for(int i = 0; i < stringCount; i++)
    {
	System.out.print("Could you enter the strings here: \n");
        stringInput[i] = stdin.readLine();
        message = message + stringInput[i] + ", ";
    }
    System.out.println("So you entered:\n" + message);
     int j;
     boolean flag = true;   // set flag to true to begin first pass
     String temp = null;   //holding variable
     while ( flag )
     {
            flag = false;    //set flag to false awaiting a possible swap
            for (j=0; j<stringInput.length; j++){
                if(stringInput[j].compareTo(stringInput[j+1]) > 0)
                {
                    temp = stringInput[j];
                    stringInput[j] = stringInput[j+1];
                    stringInput[j=1] = temp;
                    flag = true;
                }
            }
            
     }
     System.out.println("The sorted strings are:" + temp);
  }
  public static void BubbleSort(String[] stringInput)
  {
     int j;
     boolean flag = true;   // set flag to true to begin first pass
     String temp = null;   //holding variable
     while ( flag )
     {
            flag = false;    //set flag to false awaiting a possible swap
            for (j=0; j<stringInput.length; j++){
                if(stringInput[j].compareTo(stringInput[j+1]) > 0)
                {
                    temp = stringInput[j];
                    stringInput[j] = stringInput[j+1];
                    stringInput[j=1] = temp;
                    flag = true;
                }
            }
            System.out.println("The sorted strings are:" + temp);
     }
  }
}

This is my code. I was using bubble sort but it didnt go to well. Could someone help.
P.S. I cant use Java.util at all.

[NormR1]

it didnt go to well.

Can you copy and paste the programs output here and add some comments about what is wrong.

[vishal1949]

package sorting;
import java.io.*; 

public class Sorting
{
    private static BufferedReader stdin =  new BufferedReader( new InputStreamReader( System.in ) );// this is for retrieving an input

    public static void BubbleSort(String[] stringInput)/* this is where bubble sort comes into handy but doesnt work at all and nothing runs it goes to the next thing*/
    {
        int j;
        boolean flag = true;   // set flag to true to begin first pass
        String temp = null;   //holding variable
        while ( flag )
        {
            flag = false;    //set flag to false awaiting a possible swap
            for (j=0; j<stringInput.length; j++){/* this is the part where i am totally lost */
                if(stringInput[j].compareTo(stringInput[j+1]) > 0)
                {
                    temp = stringInput[j];
                    stringInput[j] = stringInput[j+1];
                    stringInput[j+1] = temp;
                    flag = true;
                }
            }    
        }
        System.out.println("The sorted strings are:" + temp);// this doesnt even run when i want it to.
    }
    public static void main(String[] arguments) throws IOException
    {
        System.out.println("How many strings would you like to enter?");
        int stringCount = Integer.parseInt(stdin.readLine());// retrieving the numeber of string the user wants to input
        String[] stringInput = new String[stringCount];// Creating an array that contains stringCount strings
        String message = "";// using this so i can println
        for(int i = 0; i < stringCount; i++)// using for loop so that user could input as many times as he want
        {
	    System.out.print("Could you enter the strings here: \n");
            stringInput[i] = stdin.readLine();
            message = message + stringInput[i] + ", ";
        }
        System.out.println("So you entered:\n" + message);// this will show what the user in
    }
}

[NormR1]

Can you copy and paste the program's output here and add some comments about what is wrong.

[vishal1949]

Can you copy and paste the program's output here and add some comments about what is wrong.

package sorting;
import java.io.*; 

public class Sorting
{
    private static BufferedReader stdin =  new BufferedReader( new InputStreamReader( System.in ) );// this is for retrieving an input

    public static void BubbleSort(String[] stringInput)// this is where bubble sort comes into handy
    {
        int j;
        boolean flag = true;   // set flag to true to begin first pass
        String temp = null;   //holding variable
        while ( flag )
        {
            flag = false;    //set flag to false awaiting a possible swap
            for (j=0; j<stringInput.length; j++){/* this is the part where i am totally lost */
                if(stringInput[j].compareTo(stringInput[j+1]) > 0)
                {
                    temp = stringInput[j];
                    stringInput[j] = stringInput[j+1];
                    stringInput[j+1] = temp;
                    flag = true;
                }
            }    
        }
        System.out.println("The sorted strings are:" + temp);// this doesnt even run when i want it to.
    }
    public static void main(String[] arguments) throws IOException
    {
        System.out.println("How many strings would you like to enter?");
        int stringCount = Integer.parseInt(stdin.readLine());// retrieving the numeber of string the user wants to input
        String[] stringInput = new String[stringCount];// Creating an array that contains stringCount strings
        String message = "";// using this so i can println
        for(int i = 0; i < stringCount; i++)// using for loop so that user could input as many times as he want
        {
	    System.out.print("Could you enter the strings here: \n");
            stringInput[i] = stdin.readLine();
            message = message + stringInput[i] + ", ";
        }
        System.out.println("So you entered:\n" + message);// this will show what the user in
    }
}

[Muralidharan.E]

This is my code. I was using bubble sort but it didnt go to well. Could someone help. P.S. I cant use Java.util at all.

Yor are almost correct except 2 logic mistakes..

In line no 17 :

if(stringInput[j].compareTo(stringInput[j+1]) > 0)

You are comparing with index j+1 . And you have used your for loop

for (j=0; j<stringInput.length; j++)

which is not matchable for comparision. It will throw ArrayIndexOutOfBoundsException at last.

So, reduce your array length in to -1 in for loop condition as like this.

for (j=0; j<stringInput.length-1; j++){

Before the end of main method call your BubbleSort method by passing required input.

In line no 26, you have printed temp variable which contains only 1 value.
Using for loop print your stringinput array variable which has been sorted..

I have modified your code here ..

import java.io.*; 

public class Sorting
{
    private static BufferedReader stdin =  new BufferedReader( new InputStreamReader( System.in ) );// this is for retrieving an input

    public static void BubbleSort(String[] stringInput)// this is where bubble sort comes into handy
    {
        int j;
        boolean flag = true;   // set flag to true to begin first pass
        String temp = null;   //holding variable
        while ( flag )
        {
            flag = false;    //set flag to false awaiting a possible swap
            for (j=0; j<stringInput.length-1; j++){/* this is the part where i am totally lost */
                if(stringInput[j].compareTo(stringInput[j+1]) > 0)
                {
                    temp = stringInput[j];
                    stringInput[j] = stringInput[j+1];
                    stringInput[j+1] = temp;
                    flag = true;
                }
            }    
        }
        System.out.println("The sorted strings are:" );// this doesnt even run when i want it to.
        for(int i=0;i<stringInput.length;i++){
            System.out.println(stringInput[i]);
        }
    }
    public static void main(String[] arguments) throws IOException
    {
        System.out.println("How many strings would you like to enter?");
        int stringCount = Integer.parseInt(stdin.readLine());// retrieving the numeber of string the user wants to input
        String[] stringInput = new String[stringCount];// Creating an array that contains stringCount strings
        String message = "";// using this so i can println
        for(int i = 0; i < stringCount; i++)// using for loop so that user could input as many times as he want
        {
	    System.out.print("Could you enter the strings here: \n");
            stringInput[i] = stdin.readLine();
            message = message + stringInput[i] + ", ";
        }
        System.out.println("So you entered:\n" + message);// this will show what the user in
        BubbleSort(stringInput);
    }
}