Can any body help me out to solve this issue
String expr ="1.3*60";
//Integer xx=Integer.valueOf();
int i = Integer.parseInt(expr);
System.out.println("xx "+i);
When i am compiling this it shows Number Format Exception, I am in Beginning Stage in java, so please help me out to solve this, Thanks a ton
Integer.parseInt does not evaluate mathematical expressions; it simply converts a String format of an integer to an Integer type.
For example:
int x = 5;
int y = Integer.parseInt("5");
x == y; // => true
To evaluate mathematical expressions like 1.3 * 60 = ?, you might want to search for Java math parsing/evaluation libraries. (see this question, for example)
"1.3*60";
is not a valid integer.
Integer.parseInt(...); can parse only valid integer
If you want to use expression evaluation engines. See this and this
String[] tokens = expr.split(delims);
...
int i = Integer.parseInt(expr);
You've already split the string into a float and an int, so you need to pass your "tokens[0]" and "tokens[1]" strings into parseInt() instead of your original string "expr", although on of those strings is a float, so I'm not sure if even that will work.
Check this code:
String expr ="1.3*60";
String[] tokens = expr.split("\\*");
float j = Float.parseFloat(tokens[0]);
float k = Float.parseFloat(tokens[1]);
System.out.println(j);
System.out.println(k);
System.out.println(j*k);
So, first you have to tokenize using a regular expresion (I wont talk about that), so that is the split part you had. Then, as some of the numbers you are parsing are not integers you should use floats or the corresponding type, or use try/catchs or whatever to ignore non int values. And lastly, valueOf returns objects while parseX returns primitives, which I think are the ones you need.
If you are using jdk 1.6, you can use inbuilt javascript engine to evaluate expression:
import javax.script.ScriptEngineManager;
import javax.script.ScriptEngine;
public class expressionEvaluate{
public static void main(String[] args) throws Exception{
ScriptEngineManager sem = new ScriptEngineManager();
ScriptEngine scriptEngine = sem.getEngineByName("JavaScript");
String expr = "1*3+5";
System.out.println(scriptEngine.eval(expr));
}
}
