Common errors

Compile errors come from javac and name the file and line (./Main.java:5: error: …). Exceptions happen while running; read the first line for the type and the at … lines for where.

• error: cannot find symbol — a typo in a name, a variable used outside its block, or a missing import.
• error: incompatible types: String cannot be converted to int — convert with Integer.parseInt(text).
• error: missing return statement — some path through the method does not return.
• error: class Geometry is public, should be declared in a file named Geometry.java — rename the file or the class.
• error: ';' expected — usually on the line above the one shown.
• NullPointerException — calling a method on null; the message names the variable that was null.
• ArrayIndexOutOfBoundsException: Index 3 out of bounds for length 3 — indexes run from 0 to length - 1.
• NumberFormatException: For input string: "x" — the text is not a number.
• NoSuchElementException from Scanner — there is no more input; fill in the Input tab.

public class Main {
    public static void main(String[] args) {
        String[] values = {"10", "x", "7"};
        int total = 0;
        for (String v : values) {
            try {
                total += Integer.parseInt(v);
            } catch (NumberFormatException e) {
                System.out.println("skipped " + v);
            }
        }
        System.out.println("total: " + total);
    }
}

skipped x
total: 17