Java codes for Lab Classes of Computer Science & Engineering's Courses
import java.util.Scanner;
public class FinalFirstClass {
public static void main(String[] args) {
Scanner scan= new Scanner(System.in);
String word;
int a=0;
System.out.println("Please enter a string : ");
word=scan.nextLine();
if (word.charAt(0)=='a' || (word.charAt(0)=='a' && word.charAt(1)=='a')) {
if (word.length()==1) {
System.out.println(word+" is recognized by a*");
}
else if (word.length()==2) {
System.out.println(word+" is recognized by a*");
}
else if (word.charAt(0)=='a' && word.charAt(1)=='a' && word.charAt(2)=='b' ) {
System.out.println(word+" is recognized by aab");
}
else if (word.length()>=2) {
for (int i = 0; i < word.length()-1; i++) {
if (word.charAt(i)=='a') {
a=1;
}
else if(word.charAt(i)=='a' || word.charAt(i)=='b'){
a=0;
}
}
if (a==1) {
System.out.println(word+" is recognized by a*");
}
else if (a==0) {
System.out.println(word+" is recognized by a*b+");
}
}
else {
System.out.println(word+" is recognized by a*b+");
}
}
else if (word.charAt(0)=='a' && word.charAt(1)=='a' && word.charAt(2)=='b' ) {
System.out.println(word+" is recognized by aab");
}
else {
System.out.println("String can not recogniged");
}
}
}
Please enter a string :
abcd
abcd is recognized by a*b+
--------------------
Please enter a string :
aab
aab is recognized by aab
--------------------
Please enter a string :
xyz
String can not recogniged
Example 2: A java code to determine a string is recogniged as prefix, postfix, infix, Evaluation or not.
import java.util.Scanner;
public class FinalSecondClass {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
String word;
int evaliation = 0;
int a = 0, b = 0, c = 0, sum = 0;
System.out.println("Please Enter an string: ");
word = scan.next();
int length = word.length() - 1;
if (word.charAt(0) == '+' || word.charAt(0) == '-' || word.charAt(0) == '*' || word.charAt(0) == '/') {
System.out.println("Given string is prefix");
evaliation = 1;
} else if (word.charAt(length) == '+' || word.charAt(length) == '-' || word.charAt(length) == '*'
|| word.charAt(length) == '/') {
System.out.println("Given string is postfix");
evaliation = 2;
} else if (word.charAt(0) != '+' || word.charAt(0) != '-' || word.charAt(0) != '*'
|| word.charAt(0) != '/' && (word.charAt(length) == '+' || word.charAt(length) == '-'
|| word.charAt(length) == '*' || word.charAt(length) == '/')) {
System.out.println("Given string is infix");
evaliation = 3;
}
if (evaliation == 3) {
if (word.charAt(0) == '0') {
a = 0;
} else if (word.charAt(0) == '1') {
a = 1;
} else if (word.charAt(0) == '2') {
a = 2;
} else if (word.charAt(0) == '3') {
a = 3;
} else if (word.charAt(0) == '4') {
a = 4;
} else if (word.charAt(0) == '5') {
a = 5;
} else if (word.charAt(0) == '6') {
a = 6;
} else if (word.charAt(0) == '7') {
a = 7;
} else if (word.charAt(0) == '8') {
a = 8;
} else if (word.charAt(0) == '9') {
a = 9;
}
// for calculte b
if (word.charAt(2) == '0') {
a = 0;
} else if (word.charAt(2) == '1') {
b = 1;
} else if (word.charAt(2) == '2') {
b = 2;
} else if (word.charAt(2) == '3') {
b = 3;
} else if (word.charAt(2) == '4') {
b = 4;
} else if (word.charAt(2) == '5') {
b = 5;
} else if (word.charAt(2) == '6') {
b = 6;
} else if (word.charAt(2) == '7') {
b = 7;
} else if (word.charAt(2) == '8') {
b = 8;
} else if (word.charAt(2) == '9') {
b = 9;
}
// for calculte c
if (word.charAt(4) == '0') {
c = 0;
} else if (word.charAt(4) == '1') {
c = 1;
} else if (word.charAt(4) == '2') {
c = 2;
} else if (word.charAt(4) == '3') {
c = 3;
} else if (word.charAt(4) == '4') {
c = 4;
} else if (word.charAt(4) == '5') {
c = 5;
} else if (word.charAt(4) == '6') {
c = 6;
} else if (word.charAt(4) == '7') {
c = 7;
} else if (word.charAt(4) == '8') {
c = 8;
} else if (word.charAt(4) == '9') {
c = 9;
}
if (word.charAt(1) == '+') {
sum = a + b;
} else if (word.charAt(1) == '*') {
sum = a * b;
} else if (word.charAt(1) == '/') {
sum = a / b;
} else if (word.charAt(1) == '-') {
sum = a - b;
}
if (word.charAt(3) == '+') {
sum = sum + c;
} else if (word.charAt(3) == '*') {
sum = sum * c;
} else if (word.charAt(3) == '/') {
sum = sum / c;
} else if (word.charAt(3) == '-') {
sum = sum - c;
}
System.out.println("Evaluation= " + sum );
}
else if (evaliation==1) {
Character ch1,ch2,ch3,ch4,ch5;
ch1=word.charAt(0);
ch2=word.charAt(1);
ch3=word.charAt(2);
ch4=word.charAt(3);
ch5=word.charAt(4);
System.out.println(ch1+ch2+ch3+ch4+ch5);
}
}
}
Please Enter an string:
hello
Given string is infix
Evaluation= 0
------------------
Please Enter an string:
anterior/
Given string is postfix
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Scanner;
public class FindFIRSTusingFile {
public static void main(String[] args) {
try
{
boolean create=true;
Scanner KB=new Scanner(System.in);
System.out.print("Enter Source File Name:");
String sfilename=KB.next();
File srcfile=new File(sfilename);
if(!srcfile.exists())
{
System.out.println("File Not Found..");
}
else
{
FileInputStream FI=new FileInputStream(sfilename);
System.out.print("Enter Target File Name:");
String tfilename=KB.next();
File tfile=new File(tfilename);
if(tfile.exists())
{
System.out.print("File Already Exist OverWrite it..Yes/No?:");
String confirm=KB.next();
if(confirm.equalsIgnoreCase("yes"))
{
create=true;
}
else
{
create=false;
}
}
if(create)
{
FileOutputStream FO=new FileOutputStream(tfilename);
int b;
/*while((b=FI.read())!=-1)
{ if (b) {
}
FO.write(b);
}*/
//read content and write in another file
while((b=FI.read())!=-1)
{
FO.write(b);
}
System.out.println("\nFIRST of the given grammer is Copied in File.");
}
FI.close();
}
}
catch(IOException e)
{
System.out.println(e);
}
}
}
