如何使方法在应用程序的生命周期中仅运行一次

Question

I have a method that fills in a file with default values and I call that method in the constructor. I want that method to run only once ( I mean by only once so when the user press the play button /in eclipse/ then that method will not run in the second press.

I have tried something like this but it doesn't work :

private boolean defaultExecuted;
public synchronized void defaultStatsFile()
{
    if (defaultExecuted)
    {
        return;
    }
    else
    {
        fileReadNWrite.configWriter("panel1", "non-US incidents");
        fileReadNWrite.configWriter("panel2", "Hoaxes");
        fileReadNWrite.configWriter("panel3", "Under NUFORC investigation");
        fileReadNWrite.configWriter("panel4", "Likliest Shape");
        defaultExecuted = true;
    }

}

Is there a smarter way to fill in a file only once ?

Please if something is not clear comment and I will reply. Any help is appreciated.

Answer 1

Better you fill data in static block

like : including proper exception handling in Main class , this way no need to dependent on constructor to load default data in file.

static {
            fileReadNWrite.configWriter("panel1", "non-US incidents");
            fileReadNWrite.configWriter("panel2", "Hoaxes");
            fileReadNWrite.configWriter("panel3", "Under NUFORC investigation");
            fileReadNWrite.configWriter("panel4", "Likliest Shape");
            defaultExecuted = true;
}

Answer 2

因为所有代码都在类中，并且您可以有多个独立类加载器，所以您无法在Java中执行此操作，因此需要Java之外的一些资源。