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Converting char to int for in java switch statement [duplicate]

This question already has answers here:
In a switch statement, why are all the cases being executed?
(8 answers)
Closed last year.
I am working on the game where the columns of the board are represented by the characters but i would like to assign them an index.
I have decided to use the switch statement in that case, however it does produce the wrong result.
With the current code I attach, it gives me 14 as an index, however since the string is 7h, and it takes h as a char, it should give an index of 7. What Could be an issue? Thanks in advance!
public class Check {
public int columnToInt(char c) {
int index=0;
switch(c) {
case 'a':
index=0;
case 'b':
index=1;
case 'c':
index=2;
case 'd':
index=3;
case 'e':
index=4;
case 'f':
index=5;
case 'g':
index=6;
case 'h':
index=7;
case 'i':
index=8;
case 'j':
index=9;
case 'k':
index=10;
case 'l':
index=11;
case 'm':
index=12;
case 'n':
index=13;
case 'o':
index=14;
}
return index;
}
public static void main(String[] args) {
String myStr = "7h";
char c =myStr.charAt(1);
System.out.println("the char at position 1 is "+c);
Check check = new Check();
int result = check.columnToInt(c);
System.out.println(result);
}
}

Java switch statements can be a bit annoying to use. You need to use break or all the cases after the expected one will be executed as well.
switch(c) {
case 'a':
index=0;
break;
Alternatively you can use a return.
switch(c) {
case 'a':
return 0;

You must add the break keyword for each case.
For example:
case 'a':
index=0;
break;
otherwise next assignments are applied.

How do I assign a number to a letter in Java

I am working on a rather unique coding situation in Java. The purpose of the program I am trying to write is to take an Amateur Radio call sign, convert the letters in the call sign into numbers as defined by a list or other structure, treat the number as its face integer value, and run these numbers through several mathematical operations to output a unique "User Code" at the end. The length of characters, as well as the number itself, will vary from user to user based on their call sign, which is fine. The biggest obstacle I have encountered is that I do not want the letters to be assigned values in a 1-26 or 0-25 type pattern. I will post my code in a moment to show you. For the moment, the end use of this User Code is unimportant to this example, but suffice it to say that since I will be the only one using this particular code example I am not very concerned with doing validity checks or the like as I will ensure the integrity of the input data manually. With this being said, I do have a working solution which I will post here, but my question is not "it doesn't work" because it does work, my problem is that it is, in my opinion, bloated, and something tells me it could be cut down considerably. Here is the code, and following are some alternatives I considered but rejected:
import java.util.*;
import java.io.*;
public class UserCode
{
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
int baseNumber = 0;
int finalNumber;
String callSign;
System.out.println("Enter CallSign for Code Generation: ");
callSign = in.nextLine();
String s = callSign.toUpperCase();
for (int i = 0; i < s.length(); i++)
{
char c = s.charAt(i);
if (Character.isDigit(c))
{
int l = Character.getNumericValue(c);
baseNumber = baseNumber + l;
}
else if (Character.isLetter(c))
{
int letNum = 0;
switch (c)
{
case 'A':
letNum = 23;
break;
case 'B':
letNum = 17;
break;
case 'C':
letNum = 5;
break;
case 'D':
letNum = 11;
break;
case 'E':
letNum = 34;
break;
case 'F':
letNum = 18;
break;
case 'G':
letNum = 13;
break;
case 'H':
letNum = 31;
break;
case 'I':
letNum = 27;
break;
case 'J':
letNum = 25;
break;
case 'K':
letNum = 7;
break;
case 'L':
letNum = 25;
break;
case 'M':
letNum = 33;
break;
case 'N':
letNum = 26;
break;
case 'O':
letNum = 28;
break;
case 'P':
letNum = 16;
break;
case 'Q':
letNum = 14;
break;
case 'R':
letNum = 2;
break;
case 'S':
letNum = 4;
break;
case 'T':
letNum = 6;
break;
case 'U':
letNum = 8;
break;
case 'V':
letNum = 10;
break;
case 'W':
letNum = 37;
break;
case 'X':
letNum = 12;
break;
case 'Y':
letNum = 3;
break;
case 'Z':
letNum = 1;
break;
default:
System.out.println("Call Contains a bad character. Try again. \n");
}
baseNumber = baseNumber + letNum;
}
}
System.out.println("\n");
String baseStr = Integer.toString(baseNumber);
System.out.println("The Base number is: " + baseStr + "\n");
int sMod = baseNumber%7;
String sModStr = Integer.toString(sMod);
System.out.println("The Check Digit is: " + sModStr + "\n");
String combine = baseStr + sModStr;
int nextOp = Integer.parseInt(combine);
finalNumber = nextOp * nextOp;
String finalStr = Integer.toString(finalNumber);
System.out.println("The User Code is: " + finalStr + "\n");
}
}
Okay, as I said this code works, but it is long. I had considered a few alternatives, none of which will really work. The first was Enum, but that obviously is outside my parameters as it produces a 1-26 incremented pattern. There are several variations of this using various for{} loops but the result there is the same. I even considered a new HashMap and map.put statements, but that's only marginally shorter and it would seem to me that creating a hashmap would, in the end, actually use more memory than my current solution. As you can see, I did not .split or use .toCharArray() since these created separate entities in memory that I did not need. All the information I needed was already contained in the string itself, except for my chosen numerical values. Finally, I could have created another class file with this assignment code, but the result is the same: the length itself hasn't been changed it's been spread over two files (and actually increased in calling the method).
Having put this out here, can anyone see any way I can shorten this code, particularly in the area of the switch{} block and still retain the same result with the same numerical values? I would be highly interested in any suggestions that can be made in this regard. BTW I didn't mention this but this is not a school assignment, this is a personal project, though my level of Java knowledge is about at that of a beginner taking my first Java class LOL. Thanks

if you want to stick with this logic then use a HashMap<Character, Integer> and setup only once the values like: map.put('Z', 1); and so on, then u don't need the switch. You can get the values by using: map.get('Z'); which will return every time 1
it is easy to implement and easy to change the code if needed

Create an array of corresponding integers:
int[] letnums = {23, 17, 5, ... };
char c = s.charAt(i);
if (Character.isLetter(c)) {
int letnum = letnums(c);
...
}

How do you place a class in the default package in netbeans for Mac?

My instructor requires us to take the package from our code and make it a default package. The only problem is he taught us how to do that through Windows and I have a MacBook so his way isn't working. I can't figure out how to do it. I've attached the code to the bottom in case that will help.
package romannumeralcalculator;
import java.util.*;
public class RomanNumeralCalculator
{
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);
int integer;
do {
System.out.print("Please enter an interger from 1 to 5999. Enter a negative number to exit. \n ->");
integer = input.nextInt();
} while (integer >= 6000);
while (integer == 0) {
System.out.println("");
break;
}
String results = "";
int ones = integer % 10;
int tens = (integer / 10) % 10;
int hundreds = (integer / 100) % 10;
int thousands = (integer / 1000) % 1000;
switch (thousands) {
case 1:
results += "M";
break;
case 2:
results += "MM";
break;
case 3:
results += "MMM";
break;
case 4:
results += "MMMM";
break;
case 5:
results += "MMMMM";
break;
default:
System.out.println("");
}
switch (hundreds) {
case 1:
results += "C";
break;
case 2:
results += "CC";
break;
case 3:
results += "CCC";
break;
case 4:
results += "CD";
break;
case 5:
results += "D";
break;
case 6:
results += "DC";
break;
case 7:
results += "DCC";
break;
case 8:
results += "DCCC";
break;
case 9:
results += "CM";
break;
default:
System.out.println("");
}
switch (tens) {
case 1:
results += "X";
break;
case 2:
results += "XX";
break;
case 3:
results += "XXX";
break;
case 4:
results += "XL";
break;
case 5:
results += "L";
break;
case 6:
results += "LX";
break;
case 7:
results += "LXX";
break;
case 8:
results += "LXXX";
break;
case 9:
results += "XC";
break;
default:
System.out.println("");
}
switch (ones) {
case 1:
results += "I";
break;
case 2:
results += "II";
break;
case 3:
results += "III";
break;
case 4:
results += "IV";
break;
case 5:
results += "V";
break;
case 6:
results += "VI";
break;
case 7:
results += "VII";
break;
case 8:
results += "VIII";
break;
case 9:
results += "IX";
break;
default:
System.out.println("");
}
System.out.println(results);
}
}

In the projects tab of Netbeans in the top-left:
Expand the tree for your Project.
Expand the Source Packages folder.
Expand the package with your java file.
Drag the java file from under the package to the Source Packages folder.
A dialog box will pop up with the title Move Class. On that dialog click the Refactor button.
This should be the same procedure in Windows. I am not sure why your professor told you something different.

Switch Statement Inside a method of another class [closed]

Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.
This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 8 years ago.
Improve this question
public int alphCheck(char check){
switch(check){
case 'a':
return 1;
break;
case 'b':
return 2;
break;
case 'c':
return 3;
break;
case 'd':
return 4;
break;
case 'e':
return 5;
break;
case 'f':
return 6;
break;
case 'g':
return 7;
break;
case 'h':
return 8;
break;
case 'i':
return 9;
break;
case 'j':
return 10;
break;
case 'k':
return 11;
break;
case 'l':
return 12;
break;
case 'm':
return 13;
break;
case 'n':
return 14;
break;
case 'o':
return 15;
break;
case 'p':
return 16;
break;
case 'q':
return 17;
break;
case 'r':
return 18;
break;
case 's':
return 19;
break;
case 't':
return 20;
break;
case 'u':
return 21;
break;
case 'v':
return 22;
break;
case 'w':
return 23;
break;
case 'x':
return 24;
break;
case 'y':
return 25;
break;
case 'z':
return 26;
break;
}
}
PS.This was done in another class
I want to be able to use this method in the main class, to input a letter, and return a number/index for that letter.
But I kept getting: this method must return a result of type int.
Very Confused. Please help. Thx.

Here's a question to consider: What happens if the inputted letter isn't one of the cases you described?
While you may know that you're only feeding in letters, the compiler doesn't know that, and because it can't figure out what to return if one of the cases you defined isn't hit, emits an error as a result. You'll need to put in a default case, so the compiler knows that the method is guaranteed to return something:
switch(check) {
case 'a':
...
default:
// return something or maybe print/throw an error
}
A better solution for this may be to use the fact that chars are just numbers in a different form. For example, 'a' is equivalent to the integer 97 (check out the table here for a table of characters and their ASCII numerical equivalents). So you can do a math trick to get equivalent results:
public int alphCheck(char check) {
return check - 'a' + 1;
}

you have to provide return type like return 0; at the end of your switch statement.or in default: case
switch(check) {
..
default:
return 0;
}

i want to replace java code using if-else to switch [closed]

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Closed 9 years ago.
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i want java code using switch to same execute ? how i can do this by java
if(ave>=90.0)
return 'A';
else if(ave>=80.0)
return 'B';
else if(ave>=70.0)
return 'C';
else if(ave>=60.0)
return 'D';
else
return 'F';

The intuitive solution is: It's impossible.
A switch needs a discreet set of elements. A range of numbers is infinite and you can't do
switch(something) {
case 90.0:
case 90.000000000001:
....
There is a way you could do that though: Convert the range to some number:
private static int toRangeIndex(double d) {
if (d >= 90.0)
return 0;
else if (d >= 80.0)
return 1;
else if (d >= 70.0)
return 2;
else if (d >= 60.0)
return 3;
else
return 4;
}
public static double sumColoumn(double[][] m, int coloumnIndex) {
switch (toRangeIndex(ave)) {
case 0:
return 'A';
case 2:
return 'B';
case 3:
return 'C';
case 4:
return 'D';
default:
return 'F';
}
}
This is obviously not better in your case. But there are cases in which you could use such a technique.

Not possible directly, switch requires exact match.
What you can do is write function like:
int classify(double avg) {
// perform some if-else chain, or loop with test inside, or calculation:
return (int)(avg/10.0);
}
Then use the return value in switch:
switch (classify (avg)) {
case 10: // average of exact 100.0 gives 10, let's not F that...
case 9:
return 'A';
case 8:
return 'B';
//...
default:
return 'F';
}
But, in your specific case it is just moving the if... ladder into a different function, and probably not good idea. So don't do it :-).
Or rather, if you do it, do it because it makes code easier to understand and maintain (and here it in my opinion does not), not because you want to use switch statement.

int findIndex(double ave){
int index=(int)(ave/10.0);
if(index>=9)
return 9;
else
return index;
}
switch (findIndex(ave)) {
case 9:
return 'A';
case 8:
return 'B';
case 7:
return 'C';
case 6:
return 'D';
default:
return 'F';
}

i finded answer
switch(t1)
{
case 100: case 99: case 98: case 97:case 96:case 95:case 94:case 93:case 92:case 91:case 90:
cr='A';
break;
case 89: case 88: case 87: case 86:case 85:case 84:case 83:case 82:case 81:case 80:
cr='B';
break;
case 79: case 78: case 77: case 76:case 75:case 74:case 73:case 72:case 71:case 70:
cr='C';
break;
case 69: case 68: case 67: case 66:case 65:case 64:case 63:case 62:case 61:case 60:
cr='D';
break;
default:
cr = 'F';
break;
}