I've made a very simple console calculator using Java with my very limited knowledge.
The program has to perform basic math functions (+,-,*,/) on just two numbers. The program asks for two String values in the beginning, namely inpmode and outmode . The inpmode is the mode in which the user will enter his two numbers (the two modes are "dec" for decimal inputs and "bin" for binary inputs). outmode is the mode in which the user wants his result to be displayed in. This information, ( inpmode and outmode) is written to a text file and stored somewhere, the program then proceeds to ask for the values and display results accordingly. After displaying the results, the user has three options, To exit, To keep working with the same modes, To change the modes. And this goes on until the user chooses To exit.
Here's a simple flowchart I made for the purpose.
Here's my poor code:
import java.io.*;
import java.util.*;
class FileTry {
Scanner sc=new Scanner(System.in);
String inpmode="";
String outmode="";
FileWriter fw;
BufferedWriter bw;
PrintWriter pw;
String n1,n2;
FileReader fr;
BufferedReader br;
String read;
String arr[]=new String[2];
int nu2,res,i=0;
String op; int nu1=nu2=res=0;
void main(){
try {
fr=new FileReader("C:\\Users\\dell pc\\Desktop\\tryer.txt");
askdata();
}
catch (IOException e) {
try
{
System.out.println("File needs to be created first");
fw=new FileWriter("C:\\Users\\dell pc\\Desktop\\tryer.txt");
bw=new BufferedWriter(fw);
pw=new PrintWriter(bw);
askuser();
}
catch(IOException a){
System.out.println("Error");
}
}
}
void askuser()
{
System.out.println("Input mode?");
inpmode=sc.nextLine();
System.out.println("Output mode?");
outmode=sc.nextLine();
modewriter();
}
void modewriter()
{
try
{
pw.println(inpmode);
pw.println(outmode);
pw.close();
bw.close();
fw.close();
}
catch(IOException b)
{
System.out.println("error");
}
askdata();
}
void askdata()
{
System.out.println("Enter num 1");
n1=sc.nextLine();
System.out.println("Enter num 2");
n2=sc.nextLine();
System.out.println("Enter the operation");
op=sc.nextLine();
reader();
}
void reader()
{
int i=0;
try
{
Scanner fileScanner=new Scanner(new File("C:\\Users\\dell pc\\Desktop\\tryer.txt"));
while (fileScanner.hasNextLine()){
arr[i]=fileScanner.nextLine();
i++;
}
}
catch (IOException x)
{
System.out.println("errer");
}
caller();
}
void caller(){
if (arr[0].equals("bin")&&arr[1].equals("bin"))
{
todec();
operate();
tobin();
print();
}
else if(arr[0].equals("bin")&&arr[1].equals("dec"))
{
todec();
operate();
print();
}
else if(arr[0].equals("dec")&&arr[1].equals("dec"))
{
nu1=Integer.parseInt(n1);
nu2=Integer.parseInt(n2);
operate();
print();
}
else if(arr[0].equals("dec")&&arr[1].equals("bin"))
{
nu1=Integer.parseInt(n1);
nu2=Integer.parseInt(n2);
operate();
tobin();
print();
}
else System.out.println("kk");
}
void todec()
{
int decimal = 0;
int power = 0;
int binary=Integer.parseInt(n1);
while(true){
if(binary == 0){
break;
} else {
int tmp = binary%10;
decimal += tmp*Math.pow(2, power);
binary = binary/10;
power++;
}
}
nu1=decimal;
decimal = 0;
power = 0;
binary=Integer.parseInt(n2);
while(true){
if(binary == 0){
break;
} else {
int tmp = binary%10;
decimal += tmp*Math.pow(2, power);
binary = binary/10;
power++;
}
}
nu2=decimal;
System.out.println(nu1+" "+nu2);
}
void operate()
{
switch(op.charAt(0))
{
case '+' :
{ res=nu1+nu2;
break;}
case '-':
{ res=nu1-nu2;
break;}
case '/':
{ res=nu1/nu2;
break;}
case '*':
{ res=nu1*nu2;
break;}
default:
System.out.println("Errorr");
}
}
void tobin()
{
String temp="";
i=res;
while(i>0)
{
temp=(i%2)+temp;
i=i/2;
}
temp=i+temp;
res=Integer.parseInt(temp);
}
void print()
{
System.out.println(res);
System.out.println("n for another operation");
System.out.println("m to change the modes");
System.out.println("e to exit");
char c=sc.nextLine().charAt(0);
switch (c)
{
case 'n' :
{
askdata();
break;
}
case 'm' :
{
askuser();
break;
}
case 'e' :
{
System.out.println("Bye");
break;
}
default: System.out.println("errreeer");
}
}
}
The exception gets thrown when I chose to change the mode after the first run, so can someone please help me fix this?
Edit: I see the thing about my question being a duplicate of this one. I don't see how that is. I'm stuck in-between a program here while that question merely explains the error I'm getting. I need a solution or a possible suggest to make my code work.
