public static void operation1 (String[] dbcolumn1){
 
int s=Integer.parseInt( dbcolumn1[0]);
int s1=Integer.parseInt(dbcolumn1[2]);
 
 
if (dbcolumn1[1].equals("+")) {
dbcolumn1[2]=dbcolumn1[0] + dbcolumn1[2]; 
System.out.println(dbcolumn1[2]);
 
}
else if (dbcolumn1[1].equals("*")) {
dbcolumn1[2]= dbcolumn1[0] * dbcolumn1[2]; //1
}
else if (dbcolumn[1].equals("-")){
dbcolumn1[2]= dbcolumn1[0] * dbcolumn1[2]; //2
}
else if (dbcolumn1[1].equals("/")) {
dbcolumn1[2]= dbcolumn1[0] * dbcolumn1[2]; //3
}
}
    

public class Test {
	public static void main(String[] args) {
		String[] a = { "1", "+", "99" } ;
		operation1(a);
	}
	public static void operation1 (String[] dbcolumn1){
 
		// You need to place the following two statements in try-catch - in case
		// values are not really integers
 
		int s = Integer.parseInt(dbcolumn1[0]);
		int s1= Integer.parseInt(dbcolumn1[2]);
 
 
		if (dbcolumn1[1].equals("+")) {
			//dbcolumn1[2]= dbcolumn1[0] + dbcolumn1[2];
			dbcolumn1[2]= (s + s1)  + "";
			System.out.println(dbcolumn1[2]);
 
		}
		else if (dbcolumn1[1].equals("*")) {
			dbcolumn1[2]= ( s * s1 ) + "";
		}
		else if (dbcolumn1[1].equals("-")){
			dbcolumn1[2]= (s - s1) + "";
		}
		else if (dbcolumn1[1].equals("/")) {
			dbcolumn1[2]= (s/s1) + ""; // Should check for divide by zero exception
		}
	}
 
}

enum Operations {ADD, SUBTRACT, DIVIDE, MULTIPLY};
public static void operation1 (String[] dbcolumn1){
    double currentValue = 0;
    Operations operation = ADD;
    for (String s : dbcolumn1) { //this works only for Java 1.5, use tthe following lines for earlier Java versione
//    for (int i = 0; i < dbcolumn1.length; i++) {
//        String s = dbcolumn1[i];       
        if ("/".equals(s))
            operation = Operations.DIVIDE;
        else if ("*".equals(s))
            operation = Operations.MULTIPLY;
        else if ("+".equals(s))
            operation = Operations.ADD;
        else if ("-".equals(s))
            operation = Operations.SUBTRACT;
        else { //Number
            double val = 0;
            try {
                val = Double.parseDouble(s);
            } catch (NubmerFormatException e) {
                System.out.println ("Parse error. Assuming 0");
            }
            if (operation == Operations.ADD)
                currentValue = currentValue + val;
            else if (operation == Operations.SUBTRACT)
                currentValue = currentValue - val;
            else if (operation == Operations.MULTIPLY)
                currentValue = currentValue * val;
            else // divide
                currentValue = currentValue / val; //this can result in an Exception if val == 0
            operation = Operations.ADD; //this is the change I mentioned above.
        }
    }
    System.out.println (currentValue);
}