Java Basic Problems

Java: How to know which menu item is clicked??

December 1, 2010December 1, 2010 allaboutbasic

Sometimes in java, while we do GUI programming to prepare software we add menu bar(For example javax.swing.JMenuItem jMenuItem).In the menu bar we add various menu items according to our necessity.

While adding menu item, we have to indicate which menu item is clicked and which action need to be performed on that click.

Here I have given a code snippet to identify which menu item is clicked.

private javax.swing.JMenuItem jMenuItem = null;

private javax.swing.JMenuItem jMenuItem1 = null;

jMenuItem.setText(“Approve” );

jMenuItem1.setText(“Reject” );

if(jMenuItem.getText().trim().equalsIgnoreCase(“Approve” ) )

{

Do the following action

——-

—-

}

Java Basic Problems

Java: Integer (numeric) to String (word) conversion

November 30, 2010November 30, 2010 allaboutbasic

Here is a little example of java where I have converted the integer or numeric value, entered by the user, to String or word.

The given code will work for 1 to 1999. You can increase the limit by doing little change in the given code.

Here is the full code example:

import java.io.*;

class numerator

{

static String input;

static int intInput;

static String strRemainder;

static int intRemainder;

static String inWord=””;

static int firstCount=0;

public void myNumerator()

{

try

{

BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

System.out.println(“\n”);

System.out.println(“Enter the Numeric:”);

System.out.println(“\n”);

input=br.readLine();

intInput=Integer.parseInt(input);

System.out.println(“\n”);

System.out.println(“You have Entered:”+intInput);

beforeCalculator(intInput);

System.out.println(“\n”);

System.out.println(“In Word:”+inWord);

}

catch(Exception e)

{

System.out.println(“Error:”+e.getMessage());

}

public void beforeCalculator(int inputa)

{

int length;

String dividor=”1″;

int intDividor;

int intFirstValue;

String strFirstValue=””;

if (calculator(inputa).trim().toString()==”0″)

{

firstCount++;

strRemainder=Integer.toString(inputa);

length=strRemainder.length();

for(int i=0;i<length-1;i++)

{

dividor=dividor+”0″;

}

intDividor=Integer.parseInt(dividor);

intFirstValue= inputa/intDividor;

intRemainder=inputa%intDividor;

int intRemainval= intFirstValue* intDividor;

strFirstValue=calculator(intRemainval);

inWord=inWord+” “+strFirstValue;

beforeCalculator(intRemainder);

}

else

{

//beforeCalculator(intRemainval);

if(firstCount==0)

{

inWord=calculator(inputa);

}

else

{

inWord=inWord+” “+calculator(intRemainder);

}

private String calculator(int d)

{

switch(d)

{

case 1:

return “One”;

case 2:

return “Two”;

case 3:

return “Three”;

case 4:

return “Four”;

case 5:

return “Five”;

case 6:

return “Six”;

case 7:

return “Seven”;

case 8:

return “Eight”;

case 9:

return “Nine”;

case 10:

return “Ten”;

case 11:

return “Eleven”;

case 12:

return “Twelve”;

case 13:

return “Thirteen”;

case 14:

return “Forteen”;

case 15:

return “Fifteen”;

case 16:

return “Sixteen”;

case 17:

return “SevenTeen”;

case 18:

return “Eighteen”;

case 19:

return “Ninteen”;

case 20:

return “Twenty”;

case 30:

return “Thirty”;

case 40:

return “Forty”;

case 50:

return “Fifty”;

case 60:

return “Sixty”;

case 70:

return “Seventy”;

case 80:

return “Eighty”;

case 90:

return “Ninety”;

case 100:

return “One Hundred”;

case 200:

return “Two Hundred”;

case 300:

return “Three Hundred”;

case 400:

return “Four Hundred”;

case 500:

return “Five Hundred”;

case 600:

return “Six Hundred”;

case 700:

return “Seven Hundred”;

case 800:

return “Eight Hundred”;

case 900:

return “Nine Hundred”;

case 1000:

return “One Thousand”;

default:

return “0”;

}

public static void main(String args[])

{

numerator x=new numerator();

x.myNumerator();

}

OUTPUT:

Java Basic Problems

Java:Set Checkbox selected according to the value of database

November 29, 2010 allaboutbasic

Sometimes we may need to set the checkbox selected according to the value in database.

In our example buyer_name,item_number, order_number, and style_number are the database field and their value in database is set to True or False according to software requirement

Sample Database :

Config_parameter (varchar)	Config_value (varchar)
buyer_name	True
item_number	False
order_number	True
style_number	True
user_name	admin
password	xyz

Here is the sample code

Vector heading=new Vector();

heading.add(” About”);

heading.add(“Value”);

Vector config=new Vector();

Vector data=new Vector();

try {

config=Inter.getDetails(); // function Inter.getDetails() Collects data from database

data=(Vector)config.get(0);

} catch (RemoteException e) {

e.printStackTrace();

}

jtableView.setModel(new MyModel(data,heading));

jtableView.repaint();

HashMap hm=(HashMap)config.get(1);

if(hm.get(“buyer_name”)!=null)

{

// if database field (buyer_name)= =true then chkbox_buyer_name will be setSelected

chkbox_buyer_name.setSelected((hm.get(“buyer_name”).toString().equalsIgnoreCase(“true”) ? true : false));

}

if(hm.get(“item_number”)!=null)

{

// if database field (item_number)= =true then chkbox_item_number will be setSelected

chkbox_item_number.setSelected((hm.get(“item_number”).toString().equalsIgnoreCase(“true”) ? true : false));

}

if(hm.get(“order_number”)!=null)

{

// if database field (order_number)= =true then chkbox_order_number will be setSelected

chkbox_order_number.setSelected((hm.get(“order_number”).toString().equalsIgnoreCase(“true”) ? true : false));

}

if(hm.get(“style_number”)!=null)

{

chkbox_style_number.setSelected((hm.get(“style_number”).toString().equalsIgnoreCase(“true”) ? true : false));

}

if(hm.get(“style_description”)!=null)

{

chkbox_style_description.setSelected((hm.get(“style_description”).toString().equalsIgnoreCase(“true”) ? true : false));

}

Java Basic Problems

Java: Collect JTable value to Vector

November 28, 2010 allaboutbasic

Sometimes in Java programming we may need to collect the value in the JTable to a Vector

Here is a portion of the java code which is used to collect JTable value to Vector.

Code Example:

try

{

Vector data=new Vector(); // import java.util.Vector;

for(int i=0;i<jtable_config.getRowCount();i++)

{

data.add(jtable_config.getValueAt(i,0));

data.add(jtable_config.getValueAt(i,1));

System.out.println(“id”+data);

System.out.println(“name”+temp.VALUE);

}

catch (RemoteException e1)

{

e1.printStackTrace();

}

Java Basic Problems

Java: Database to HashMap

November 25, 2010 allaboutbasic

Sometimes we may need to collect data or information from database to HashMap in java. Here I have given an example to show how to collect data from database and then use it as key of HashMap.
HashMap, you may know that, takes two values, first one is KEY Value ( must be Unique) and the second one is Actual Value. Using that key value in HashMap you may search that actual value you entered.
For example:
if ( hmData.get(itMat1)==”1″)

     {
      row.add(“Yes”);
     }

In the given example hmData.put(itMat,”1″); itMat is the key value and regarding this KeyValue I have entered “1” as the actual value to use in my software.

Here is the sample code to collect or retrieve data from database to HashMap:

HashMap hmData=new HashMap();
   Connection conNew = PuConnection.DB_Connection();
   String newsql = “select distinct item_no,mat_no from a_nr_allocate_temp”;
   try
   {
   Statement stmtnew = conNew.createStatement();
   ResultSet rsNew = stmtnew.executeQuery(newsql);
   int i=1;
   while(rsNew.next()){
    String itemNo=rsNew.getString(“item_no”);
    String matNo=rsNew.getString(“mat_no”);
    String itMat= itemNo+matNo;

    hmData.put(itMat,”1″);
    System.out.println(“Inside Hashmap:for itMat”+ itMat+”Hashmap:value is:”+hmData.get(itMat));

    }
   rsNew.close();
   stmtnew.close();
   conNew.close();
   }
   catch(Exception e){}

Java Basic Problems

Java: Break String into individual Character

November 25, 2010 allaboutbasic

In String manipulation sometimes we may need to break the string into each separate or individual character.

In java we can do it easily using toCharArray() function.

In the given example, string “Java Programming ” is broken down into characters where you can see that the length of that string is 16 (including the space between “Java” and “Programming”) and the whole string is broken into each individual character , where we have stored that characters into an array.

Here is the code to convert string into array:

class StringBreaker

{

StringBreaker()

{

String s=”Java Programming”;

char[] allchars=new char[s.length()];

allchars = s.toCharArray();

System.out.println(“****************************”);

System.out.println(“\n”);

System.out.println(“Length of S:”+s.length());

System.out.println(“\n”);

for (int n=0; n<s.length(); n++)

{

try

{

System.out.println(“Character::”+(n+1)+”::”+allchars[n]);

}

catch(Exception e){}

}

System.out.println(“\n”);

System.out.println(“****************************”);

}

public static void main(String args[])

{

StringBreaker test=new StringBreaker();

}

OUTPUT:

Java Basic Problems

Java: How to pass array to another function

November 24, 2010 allaboutbasic

Sometimes we may need in java programming to pass the value of array in another function.

Here I have given an example about the procedure of passing an array to a function.

Also, here I have shown how to find out the length of an array and how to retrieve or get the value of the array after passing it to another function.

This tutorial will help you to understand the basic of array and how to declare array in java.

Code:

class ArrayPassing

{

public static void checking(String[] u)

{

System.out.println(“\n”);

System.out.println(“****************************************”);

System.out.println(“Array is entered into Checking function”);

System.out.println(“Array Length:”+u.length);

System.out.println(“Third index value is:”+u[2]);

System.out.println(“\n”);

System.out.println(“****************************************”);

}

public static void main(String args[])

{

String[] d;

d = new String[3];

d[0]=”1″;

d[1]=”2″;

d[2]=”5″;

checking(d);

}

OUTPUT:

Java Basic Problems

Java: RunTime Input from User Example

November 23, 2010November 23, 2010 allaboutbasic

I have discussed about how to take input from user in runtime from command line here.

Here I will try to give a simple example regarding this.

In this example, our program will take total student number and total subject as input, then it will take input of each subject number. After calculating the average number of total subject, if any student gets less than 40 it will show that student is failed and if any student gets more than 40 that student is passed.

Here is the given Code:

import java.io.*;

class student

{

public static void main(String args[])

{

String inputa;

int num_std; // Total Number of Student

int sub_std; // Total Subject of Student

System.out.println(“************************************”);

System.out.println(“\n”);

System.out.println(“Enter the Total Number of Students:”);

System.out.println(“\n”);

BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

try{

inputa=br.readLine();

num_std=Integer.parseInt(inputa);

System.out.println(“Enter the Total Subject of Student:”);

System.out.println(“\n”);

inputa=br.readLine();

sub_std= Integer.parseInt(inputa);

int i=0;

int j=0;

int z=0;

System.out.println(“\n”);

for (i=1;i<=num_std;i++)

{

System.out.println(“Enter Student :” +i+” :Subject Number:”);

System.out.println(“\n”);

for (j=1;j<=sub_std;j++)

{

inputa= br.readLine();

z= z+Integer.parseInt(inputa);

if(j==sub_std)

{

System.out.println(“Student:”+i+”Total Number:”+z);

int om=(z)/sub_std;

if(om<40)

{

System.out.println(“Student:”+i+”fails”);

System.out.println(“Student :”+i+” : Average Number:”+om);

om=0;

z=0;

}

else

{

System.out.println(“Student :”+i+” : passed”);

System.out.println(“Student :”+i+” : Average Number:”+om);

om=0;

z=0;

}

} //End of student subject loop

} //End of student num loop

System.out.println(“\n”);

System.out.println(“************************************”);

}

catch(IOException e)

{}

}

OUTPUT:

Java Basic Problems

Java: How to take Run time input from user

November 22, 2010November 22, 2010 allaboutbasic

Suppose you are doing your coding in java (let you are running your program from command prompt of your desktop) and you need to take input from user in command line or command prompt while user run (actually runtime input) your program.

Now I will show you how to take user input from command prompt or command line in java.

Here I have used BufferedReader and readLine() to take input from user in command line/ command prompt while the program was running or simply in run time.

In the example below br.readLine() takes input as String, in the next line we have parsed or convert that String into integer.

Code:

import java.io.*;

public class CmdLineInput

{

CmdLineInput()

{

String inputa;

int num_std;

BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

try{

System.out.println(“Enter the number of Students:”);

inputa=br.readLine();

num_std=Integer.parseInt(inputa);

System.out.println(“Number of Students:”+num_std);

}

catch(Exception e){}

}

public static void main(String args[])

{

CmdLineInput takeinput=new CmdLineInput();

}

OUTPUT:

Java Basic Problems

Java: About Static Method/Class Method.

November 21, 2010 allaboutbasic

Static Method:

I have discussed Static Variable before, you can check it from here.

Now I am going to discuss about Static Method. It is also called Class Method.

In general we can say that methods declared with the keyword Static as modifier are called Static Methods or Class Methods.

Static Method in Java is that type of method which belongs to a class rather than an object of a class. Static Methods are invoked without reference to a particular instance (object) of a class.

So, anyone can invoke a Static Method without having to instantiate an object.

Important Notes / Features:

1. In Static Method, you can only manipulate variables that are declared as static, not other variables. It is because, something that is common to a class cannot refer to things that are specific to an object.

2. Static Method can call only other Static Methods.

3. Static Method cannot reference to the current object using super or this keyword.

*** static means that it cannot be changed

Code:

public class StaticMethod

{

static int value=10;

StaticMethod()

{

test2 test =new test2();

}

public static int getValue()

{

return value;

}

public int againgetValue()

{

return value;

}

public class test2

{

test2()

{

int getvalue= StaticMethod.getValue();

System.out.println(“Test2 calling the value StaticMethod.getValue(): “+getvalue); //Correct

//int setvalue= StaticMethod.againgetValue(); ****

//System.out.println(“test2 calling the value StaticMethod.againgetValue() “+setvalue); **

}

public static void main(String args[])

{

StaticMethod test=new StaticMethod();

}

*** These 2 lines will give error message as Instant Method cant be call in this way.

OUTPUT:

Test2 calling the value StaticMethod.getValue(): 10