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javaandroidlibgdx

NoSuchMethodError for comparator?

I get the below exception on this line when I run my program in android.

private PriorityQueue<Creature> turnqueue = new PriorityQueue<Creature>(new TurnComparator());

FATAL EXCEPTION: GLThread 18092
Process: com.buckriderstudio.clonequest, PID: 10171
java.lang.NoSuchMethodError: No direct method <init>(Ljava/util/Comparator;)V in class Ljava/util/PriorityQueue; or its super classes (declaration of 'java.util.PriorityQueue' appears in /system/framework/core-libart.jar)

This is how my comparator looks:

public class TurnComparator implements Comparator<Creature> {    
    @Override
    public int compare(Creature c1, Creature c2) {
        if (c1.getNextMove() < c2.getNextMove()) return -1;
        if (c1.getNextMove() > c2.getNextMove()) return 1;
        else return 0;
    }   
}

It seems it is some kind of compatibility issue but I'm not sure how to fix this. Does Android not support a Comparator at all or do I need to change it a bit to fix this? What would be a good compatible substitute for comparing a PriorityQueue?

Solution

  • If you take a look at the java documentation, you will see that there is no such constructor for priority queue:

    https://docs.oracle.com/javase/7/docs/api/java/util/PriorityQueue.html

    You need to also specifify the initial capacity i.e.

    private PriorityQueue<Creature> turnqueue = new PriorityQueue<Creature>(5, new TurnComparator());

    Update: It's worth noting that this DOES work in Java 8 - they have added an extra constructor. https://docs.oracle.com/javase/8/docs/api/java/util/PriorityQueue.html