Develop Reference

How to put the sum of two numbers beside the " = "

I want to display the sum of two numbers beside the equal sign.
Scanner scan = new Scanner(System.in);
int i ;
System.out.println("enter a number: " );
i = scan.nextInt();
int a = i - 1 ;
while(a >= 1){
System.out.println(i +" + "+ a + " = " );
//i want to display the sum of two numbers beside the equal sign.
i =i + a ;
System.out.println(i);
a --;
// how can I display the answer beside the equal sign?
}
}
}
How can I display the answer beside the equal sign?

Change your first println to print.

As per your question I think you are most probably asking how we can show the sum of two numbers in the print statement.
So in your code after "=" you just need to add (i+a) this will sum the value of i and a.
System.out.println(i +" + "+ a + " = " + (i+a)).
I hope this answers your question.

System.out.println() method prints a "newline character" (\n) right after its' input.
There is another method that does not do this:
System.out.print()
You should change
System.out.println(i +" + "+ a + " = " ); to
System.out.print(i +" + "+ a + " = " ); this.

How to break out of a loop after an input has been checked against every item in an enum Java?

I'm trying to make a program that will allow the user to input either a name or symbol of an element from the periodic table, and will then output some data about that element. So far I've managed to get the user to be able to input either a name or a symbol and have it output correctly, but if the user inputs something wrong then the code doesn't output anything, and will stop accepting an input of a symbol and only accept an input of a name. I would like to know how I would be able to break out of the loop and tell a user that their input is invalid only after the input has been checked against every item in the enum, since my current solution doesn't work. I'm new to Java, so a simple explanation as to how and why would be greatly appreciated.
import java.util.Scanner;
public class PeriodicTable {
public enum Element {
Hydrogen("H", "Nonmetal", "1.008"),
Helium("He", "Noble Gas", "4.003"),
Lithium("Li", "Alkali Metal", "6.941"),
Beryllium("Be", "Alkaline Earth", "9.012"),
Boron("B", "Semimetal", "10.811"),
Carbon("C", "Nonmetal", "12.011"),
//The rest of the periodic table is here, I just removed it for the sake of this post.
private String symbol;
private String group;
private String weight;
private Element(String symbol, String group, String weight) {
this.symbol = symbol;
this.group = group;
this.weight = weight;
}
}
static Element cName = null;
public static void main(String[] args) {
int counter = 0;
System.out.println("Enter the name or symbol of an element in the periodic table. ");
outer:
do {
Scanner reader = new Scanner(System.in);
String input = reader.nextLine().trim();
for (Element sy : Element.values()) {
if (sy.symbol.equalsIgnoreCase(input)) {
System.out.println("Element: " + sy + " (" + sy.symbol + ")" + "\nGroup: " + sy.group + "\nAtomic Mass: " + sy.weight);
reader.close();
break outer;
} else {
try {
cName = Element.valueOf(input.substring(0, 1).toUpperCase() + input.substring(1).toLowerCase());
System.out.println("Element: " + cName + " (" + cName.symbol + ")" + "\nGroup: " + cName.group + "\nAtomic Mass: " + cName.weight);
reader.close();
break outer;
} catch(IllegalArgumentException e) {
if(counter > Element.values().length) {
System.out.println("That name or symbol is not valid. Please try again. ");
continue outer;
} else {
counter++;
continue;
}
}
}
}
} while (true);
}
}

I would avoid using the valueOf method in a loop. Instead, you can iterate over the elements and for each element check both its name (use the name method) and its symbol.
Scanner reader = new Scanner(System.in);
outer: while (true) {
System.out.println("Enter the name or symbol of an element in the periodic table. ");
String input = reader.nextLine().trim();
for (Element sy : Element.values()) {
if (sy.symbol.equalsIgnoreCase(input) || sy.name().equalsIgnoreCase(input)) {
System.out.println("Element: " + sy + " (" + sy.symbol + ")" + "\nGroup: " + sy.group + "\nAtomic Mass: " + sy.weight);
break outer;
}
}
System.out.println("No such element found. ");
}
reader.close(); // this might be a bad idea
I would also avoid closing the reader, as this will also close System.in and you will be unable to read any more input.

Assuming I understand your question, I would add the logic for parsing Element(s) to Element. You can create Map(s), one to symbol and one of name to corresponding Element instances and then invoke them in whichever order you choose. Like,
private static Map<String, Element> symbolMap = new HashMap<>();
private static Map<String, Element> nameMap = new HashMap<>();
static {
for (Element e : Element.values()) {
symbolMap.put(e.symbol.toUpperCase(), e);
nameMap.put(e.name().toUpperCase(), e);
}
}
public static Element fromString(String token) {
if (symbolMap.containsKey(token.toUpperCase())) {
return symbolMap.get(token.toUpperCase());
}
return nameMap.get(token.toUpperCase());
}
Then in main
Element e = Element.fromString("H");
Element e2 = Element.fromString("Hydrogen");
System.out.println(e == e2); // <-- true
And if e were null then it isn't a valid symbol (or name).

If I have understood correctly, you want to go through the enums and see if any of the symbols match the user input. If not, print a message and try again. You had the right approach, but in the catch block you don't need to make a counter. Instead if we think through the design, you have break outer; if the input ever matches. So the end of the do-while loop will only be reached if there is no matching element. So if we just print a message at the end, this will accomplish our goal:
outer:
do {
Scanner reader = new Scanner(System.in);
String input = reader.nextLine().trim();
for (Element sy : Element.values()) {
if (sy.symbol.equalsIgnoreCase(input)) {
System.out.println("Element: " + sy + " (" + sy.symbol + ")" + "\nGroup: " + sy.group + "\nAtomic Mass: " + sy.weight);
reader.close();
break outer;
} else {
try {
cName = Element.valueOf(input.substring(0, 1).toUpperCase() + input.substring(1).toLowerCase());
System.out.println("Element: " + cName + " (" + cName.symbol + ")" + "\nGroup: " + cName.group + "\nAtomic Mass: " + cName.weight);
reader.close();
break outer;
} catch(IllegalArgumentException e) {
continue;
}
}
}
System.out.println("Error. No matching elements. Please try again.");
} while (true);
Sample Output:
Enter the name or symbol of an element in the periodic table.
No
Error. No matching elements. Please try again.
l
Error. No matching elements. Please try again.
He
Element: Helium (He)
Group: Noble Gas
Atomic Mass: 4.003

You complicate the code by mixing the search for the name and the search for the symbol. The search for the name does not need to be inside the for loop:
public static void main(String[] args) {
Scanner reader = new Scanner(System.in);
System.out.println("Enter the name or symbol of an element in the periodic table. ");
boolean found = false;
do {
String input = reader.nextLine().trim();
try {
cName = Element.valueOf(input.substring(0, 1).toUpperCase() + input.substring(1).toLowerCase());
System.out.println("Element: " + cName + " (" + cName.symbol + ")" + "\nGroup: " + cName.group + "\nAtomic Mass: " + cName.weight);
found = true;
} catch (IllegalArgumentException e) {
}
for (Element sy : Element.values()) {
if (sy.symbol.equalsIgnoreCase(input)) {
found = true;
System.out.println("Element: " + sy + " (" + sy.symbol + ")" + "\nGroup: " + sy.group + "\nAtomic Mass: " + sy.weight);
}
}
if (!found)
System.out.println("That name or symbol is not valid. Please try again. ");
} while (!found);
reader.close();
}

How to Get a Lexical Analyzer to analyze each character entered (minus spaces)?

I'm currently trying to create a lexical analyzer in Java, and I'm having some difficulties getting the analyzer to analyze each character entered. I currently have it analyzing the code with spaces being put in between each character, but the requirements are that the analyzer should be able to detect "(sum" as "(" and "sum", so analyzing using spaces to separate them doesn't work.
My code isn't very efficient, but it currently works to analyze the entered text by using spaces in between the two. Is there a way to analyze each character entered, rather than using " " to separate them?
Here is my code:
String input = JOptionPane.showInputDialog("Enter the Math Problem:");
//input is "(sum + 47) / total"
StringTokenizer st = new StringTokenizer(input, " ");
JOptionPane.showMessageDialog(this,st.countTokens());
//Displays the header to the information table
jTextArea1.append("John D. Student, CSCI4200-DA, Fall 2018, Lexical Analyzer \n" +
"******************************************************************************** \n \n");
//Displays the input value
jTextArea1.append("Input: " + input + "\n");
while(st.hasMoreTokens()) {
//Begin displaying the next token
jTextArea1.append("Next token is: ");
String nextItem = st.nextToken();
if("(".equals(nextItem)) {
jTextArea1.append("LEFT_PAREN" + " " + "Next lexeme is " + nextItem + "\n");
}
else if("sum".equals(nextItem)) {
jTextArea1.append("IDENT" + " " + "Next Lexeme is " + "sum" + "\n");
}
else if("+".equals(nextItem)) {
jTextArea1.append("ADD_OP" + " " + "Next lexeme is " + nextItem + "\n");
}
else if("47".equals(nextItem)) {
jTextArea1.append("INT_LIT" + " " + "Next lexeme is " + "47" + "\n");
}
else if(")".equals(nextItem)) {
jTextArea1.append("RIGHT_PAREN" + " " + "Next Lexeme is " + nextItem + "\n");
}
else if("/".equals(nextItem)) {
jTextArea1.append("DIV_OP" + " " + "Next lexeme is " + nextItem + "\n");
}
else if("total".equals(nextItem)) {
jTextArea1.append("IDENT" + " " + "Next lexeme is " + "total" + "\n");
}
else {
jTextArea1.append("Unknown Character \n");
}
}
//Once the tokens are done, display the finish message
if(!st.hasMoreTokens()) {
jTextArea1.append("******************************************************************************** \n \n");
jTextArea1.append("Next token is: END_OF_FILE" + " " + "Next lexeme is EOF \n");
jTextArea1.append("Lexical analysis of the program is complete!");
}
}

As I commented above need more delimiters for tokenizing.
StringTokenizer st = new StringTokenizer(input, " ()+-");
Is a starting example of what I mean, white space, parentheses, plus and minus. Add more characters to the delimiter string to tokenize by those as well.
You should never see if a string token equals a certain number this will block further progress.
Use something like
int newnum = Integer.ParseInt(nextItem);
after you do an initial check to see if it an integer of course.

Looking up a string in a file, then copying lines after it

This is my first time posting to this site, so if I get any formatting wrong, please be easy on me Lol
I'm writing a Java program that needs to look up a part number from an inventory, and then print the part number along with the data following it. The code is only printing out the information at the top of the file, and then repeating my else statement 5 times.
Here is the code:
package inventory;
import java.util.Scanner;
import java.io.*;
public class inventory
{
public static void main(String[] args) throws IOException
{
Scanner keyboard = new Scanner(System.in);
// File Information
String parts;
File inventoryFile;
FileWriter inventoryFW;
PrintWriter inventoryPW;
Scanner inventorySC;
//User Information
String userChoice;
// Part Information
String partID, partFileID, partFileDesc, partFileLoc, partDesc, partLoc;
double partFilePrice, partPrice;
int partFileQuan, partQuan;
userChoice = ("A");
// Loop
if(userChoice.equalsIgnoreCase("Q"))
System.exit(0);
else
while(!userChoice.equalsIgnoreCase("Q"))
{
// Get Employee Decision
System.out.println("Please choose a letter: \n"
+ "L - Look Up Part \n"
+ "A - Add to Inventory File \n"
+ "E - Erase From Inventory File \n"
+ "G - Generate a Sales Slip \n"
+ "I - Add Quantity to Inventory File \n"
+ "D - Display Inventory \n"
+ "Q - Quit \n"
+ "Selection: ");
userChoice = keyboard.nextLine();
// Process User Choice
if(userChoice.equalsIgnoreCase("L"))
{ // Choice L
// Look Up Part
System.out.println("Enter Part I.D. Number: ");
partID = keyboard.nextLine();
// Do until partID is equal to partFileID
parts = "inventoryFile.txt";
inventoryFile = new File(parts);
inventorySC = new Scanner(inventoryFile);
partFileID = "0";
partFileDesc = "0";
partFilePrice = 0;
partFileLoc = "0";
partFileQuan = 0;
while(inventorySC.hasNextLine())
{
String lineFromFile = inventorySC.nextLine();
if(lineFromFile.contains(partID))
{
partFileDesc = inventorySC.nextLine();
partFilePrice = inventorySC.nextDouble();
inventorySC.nextLine();
partFileLoc = inventorySC.nextLine();
partFileQuan = inventorySC.nextInt();
System.out.println("Part I.D. Number: " + partFileID + "\n");
System.out.println("Part Description: " + partFileDesc + "\n"
+ "Part Price: " + partFilePrice + "\n"
+ "Part Location: " + partFileLoc + "\n"
+ "Part Quantity: " + partFileQuan);
}
else
System.out.println("Sorry, this part cannot be found");
}
}
}
}
}
And here is the datafile I am trying to pull from:
1234567
Clutch
45.68
Warehouse B
8
1234
Brake
66.78
Warehouse A
4
For example, if the user entered part number "1234" the program should search for that part number in the file, and then display:
1234
Brake
66.78
Warehouse A
4
Sorry about any poor code formatting, I have been fighting with this for a while now.
Any help would be greatly appreciated.

There are a few issues.
The contains will have multiple matches.
You will print "not found every line" you don't find.
You are not breaking out of the loop.
boolean found = false;
while(inventorySC.hasNextLine()){
String lineFromFile = inventorySC.nextLine();
if(lineFromFile.equals(partID)) {
partFileDesc = inventorySC.nextLine();
partFilePrice = inventorySC.nextLine();
partFileLoc = inventorySC.nextLine();
partFileQuan = inventorySC.nextLine();
System.out.println("Part I.D. Number: " + partFileID + "\n");
System.out.println("Part Description: " + partFileDesc + "\n"
+ "Part Price: " + partFilePrice + "\n"
+ "Part Location: " + partFileLoc + "\n"
+ "Part Quantity: " + partFileQuan);
found = true;
break;
}
}
if(!found)
System.out.println("Sorry, this part cannot be found");

Your issue is that you are only skipping to the next line if the part list doesn't contain your part value. You actually want to skip down 5 lines if the part is not on the 'next line'.
In your "else" statement, you'll just want to call the inventorySC.nextLine(); 4 more times to get to the next place in the file you actually want to check for a part number.
If you want the 'not found' condition to reflect more effectively that the part number actually wasn't found at all, you'll want to move that message to after it could have scanned the whole file. Set a boolean with a name like 'found' to false before the file scan. If you enter your 'contains' condition because there is a part number in the file that contains your input, set the 'found' equal to true.
At the end if the 'found' is still 'false', you can output the 'not found' message.

As MadProgrammer commented above, you'll need to use 'equals' instead of 'contains'- this is why you match on the first entry. When you find a match and output it, you need to exit the while loop using a 'break' - otherwise you output the else value for each line left over (as is happening to you). But there is one other problem in that you may need to read an entire record - not just the first line of the record - when there is no match so you don't get screwed up when an inventory item has a quantity of 1234 when searching for part number 1234.

Java program for count of number of words in table

I have written Java code that finds the no.of words in the table.
It is working within the loop, but the value becomes 0 once it exits the loop.
Please help me to get correct value.
int f=0;
int fc=0;
Statement sta4=connection.createStatement();
ResultSet rs4=sta4.executeQuery("select * from db1");
while(rs4.next())
{
word[f]=rs4.getString(1).replace("$", "");
System.out.println(" sentece ="+word[f]);
fc= countWords(word[f]);
System.out.println("The sentence has "+ fc + " words");
f++;
}
System.out.println(" count =" + fc);

int f=0;
int fc=0;
Statement sta4=connection.createStatement();
ResultSet rs4=sta4.executeQuery("select * from db1");
while(rs4.next())
{
word[f]=rs4.getString(1).replace("$", "");
System.out.println(" sentece ="+word[f]);
int fcTemp= countWords(word[f]);
System.out.println("The sentence has "+ fcTemp + " words");
fc += fcTemp;
f++;
}
System.out.println(" count =" + fc);
Use this. you werent adding up fc