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  • Re: Common Java Problems

    by
    helloworld922
    Published on March 5th, 2011 01:49 PM
    0 Comments Comments
    Problem description: Code outside of a method
    Problem category: Compile-time Problems

    Diagnosis Difficulty: Medium
    Difficulty to Fix: Easy-medium


    The two most common incarnations of this problem are not putting your code inside of the main method, or not putting initializing code inside of a static initializer block or constructor.

    Missing main method:
    public class Test
{
    int a = 5;
    for(int i = 0; i < a; ++i)
    {
        System.out.println(i);
    }
}

    Attempting to perform multi-statement initialization outside of a static initializer block/constructor.
    public class Test
{
    public static int[] myArray;
    myArray = new int[5];
    for(int i = 0; i < myArray.length; ++i)
    {
        myArray[i] = i * i;
    }
}

    Error Messages

    Unfortunately, this type of problem doesn't really have any indicative error message. You will probably get tens if not hundreds of error messages of other problems the Java compiler is finding because of this problem.

    Suggested fixes

    Missing main method: Add a main method
    public class Test
{
    public static void main(String[] args)
    {
        int a = 5;
        for(int i = 0; i < a; ++i)
        {
            System.out.println(i);
        }
    }
}

    Attempting to perform multi-statement initialization outside of a static initializer block/constructor: add a static initializer block (or a constructor, depending on if you want to initialize static or instance variables).
    public class Test
{
    public static int[] myArray;
    static
    {
        myArray = new int[5];
        for(int i = 0; i < myArray.length; ++i)
        {
            myArray[i] = i * i;
        }
    }
}
    This article was originally published in forum thread: Common Java Mistakes started by helloworld922 View original post
    1. Categories:
    2. Common Java Mistakes