Converting primitive data types causing NumberFormatException

Hello all,

Hmm, for some reason I cant convert the value of a string to byte or any other type of primitive data type. I tried to use valueOf(), decode(), and parseByte(), but none would work.

IDE: Eclipse

Code java:

---

package OTherTests;
 
public class JPM {
 
	public void stringToByte(byte b, String s){
    	b = Byte.valueOf(s);
    }
 
public static void main(String[] args){    	
    	//Init variables
    	String string2 = "Alem";
        byte byte2 = 0;
 
        JPM run = new JPM();
 
        //convert vales
        run.stringToByte(byte2, string2);
    }
}

---

 

Exception in thread "main" java.lang.NumberFormatException: For input string: "Alem"

	at java.lang.NumberFormatException.forInputString(Unk  nown Source)

	at java.lang.Integer.parseInt(Unknown Source)

	at java.lang.Byte.parseByte(Unknown Source)

	at java.lang.Byte.valueOf(Unknown Source)

	at java.lang.Byte.valueOf(Unknown Source)

	at OTherTests.JPM.stringToByte(JPM.java:6)

	at OTherTests.JPM.main(JPM.java:17)

Thanks.
-Mel

What is the byte equivalent for "Alem"? That doesn't make any sense. Those methods are suppose to take a string like "5" and convert it to the byte value 5.

Would you mind looking at the assignment? It is here:Jclass.freeforums.org • View topic - Java Primitives Assignment.

Can you show some examples of the input and what you want the output to be for your code?

Looking at the other examples they're converting a single char to other data types, not trying to parse a string object to a primitive value. In Java char's are an integer-like type who's values can be mapped to a character table to gain physical meaning. For example, the character 'A' is mapped to the integer value 0x41 (65).

You can extract a single character from a string using the charAt() method, then performing a type cast to the data type you want.

Quote:

---

Originally Posted by helloworld922

Looking at the other examples they're converting a single char to other data types, not trying to parse a string object to a primitive value. In Java char's are an integer-like type who's values can be mapped to a character table to gain physical meaning. For example, the character 'A' is mapped to the integer value 0x41 (65).

You can extract a single character from a string using the charAt() method, then performing a type cast to the data type you want.

---

Ah, thanks, I thought it also applied to Strings.

Can you show some examples of the input and what you want the output to be for your code?

Quote:

---

Originally Posted by Norm

Can you show some examples of the input and what you want the output to be for your code?

---

There will be no input, output should be something like: 77 is a java.lang.Byte. It isn't something to be used in other project, it is just an assignment to see what the members of a programming group are capable of doing.

I don't understand what the code is supposed to do if it does not have input from some source.
The input to the method in your first post was a String: "Alem"
What output did you expect with that input?

Can you explain what your problem or question is?

Quote:

---

Originally Posted by Norm

I don't understand what the code is supposed to do if it does not have input from some source.
The input to the method in your first post was a String: "Alem"
What output did you expect with that input?

Can you explain what your problem or question is?

---

Sorry I thought you meant user input. I am supposed to convert a String to primitive data types and print the value of the data type plus the name of the class using the getClass().getName() method.

Sorry for being unclear before.

-Mel

Have you solved all your problems now?

Yes, here is the finial code:

Code java:

---

/*Author: Melawe(Alem)
 * Date of completion: 09/Dec/2011
 * Code made for: JClass's first assignment, a Java Programming group.
 * Link:[url]http://jclass.freeforums.org]Jclass.freeforums.org[/url]
 *  
 */
 
public class JavaPrimitivesMel{
 
    /*make a method to display the value of a primitive
    * data type, cast it and print its value and the classes full name.
    */
    public static void printClassName(Object obj){
		System.out.println(obj + " is a " + obj.getClass().getName());
	}	
 
    public static void main(String[] args){
	String convertMe = "Alem";
	byte testByte = (byte) convertMe.charAt(0);
	short testShort = (short) convertMe.charAt(1);
	int testInt = convertMe.charAt(2);
	long testLong = convertMe.charAt(3);
	double testDouble = convertMe.charAt(2);
	float testFloat = convertMe.charAt(1);
	char  testChar = convertMe.charAt(0);
 
	JavaPrimitivesMel.printClassName(testByte);
	JavaPrimitivesMel.printClassName(testShort);
	JavaPrimitivesMel.printClassName(testInt);
	JavaPrimitivesMel.printClassName(testLong);
	JavaPrimitivesMel.printClassName(testDouble);
	JavaPrimitivesMel.printClassName(testFloat);
	JavaPrimitivesMel.printClassName(testChar);
    }
}

---

[consol]run:
65 is a java.lang.Byte
108 is a java.lang.Short
101 is a java.lang.Integer
109 is a java.lang.Long
101.0 is a java.lang.Double
108.0 is a java.lang.Float
A is a java.lang.Character
BUILD SUCCESSFUL (total time: 2 seconds)[/console]

Thanks all, it is much appreciated! :D
-Mel