store X and Y coordinates

问题

Hi im new to this site and need help with a program im working on. the problem im having is that i cant seem to store string and two integers (as the coordinates). i have looked at other code but dont see how the values are stored. below is the code ive been using. the code seems to be fine but when trying to stored the values i cant put multiply integers. thanks for your time

import java.util.HashMap;
public class map {

    class Coords {
        int x;
        int y;

        public boolean equals(Object o) {
            Coords c = (Coords) o;
            return c.x == x && c.y == y;
        }

        public Coords(int x, int y) {
            super();
            this.x = x;
            this.y = y;
        }

        public int hashCode() {
            return new Integer(x + "0" + y);
        }
    }

    public static void main(String args[]) {

        HashMap<Coords, Character> map = new HashMap<Coords, Character>();
        map.put(new coords(65, 72), "Dan");
    }

}

回答1:

There seems to be several issues:

"Dan" is a String, not a Character
case is important in Java (new coords(65,72) should be new Coords(65,72))
Coords needs to be static to be instantiated without a reference to an instance the enclosing map class.

This should work:

static class Coords {
    ...
}

Map<Coords, String> map = new HashMap<Coords, String>();
map.put(new Coords(65, 72), "Dan");

ps: although you are allowed to name a local variable map within a class map, it is not a good idea to have such name collision. In Java, classes generally start in upper case, so you could rename your class Map. But it happens that Map is a standard class in Java. So call your class Main or Test or whatever is relevant. ;-)

回答2:

There is a class in java called Class Point.

http://docs.oracle.com/javase/7/docs/api/java/awt/Point.html

A point representing a location in (x,y) coordinate space, specified in integer precision.

You can see and example in this link: http://www.java2s.com/Tutorial/Java/0261__2D-Graphics/Pointclass.htm

import java.awt.Point;

class PointSetter {

  public static void main(String[] arguments) {
    Point location = new Point(4, 13);

    System.out.println("Starting location:");
    System.out.println("X equals " + location.x);
    System.out.println("Y equals " + location.y);

    System.out.println("\nMoving to (7, 6)");
    location.x = 7;
    location.y = 6;

    System.out.println("\nEnding location:");
    System.out.println("X equals " + location.x);
    System.out.println("Y equals " + location.y);
  }
}

I hope this can help you!

回答3:

Adding to @assylias

Make you inner class static in order to insert new objects like you have or new Outer().new Inner() .
Take care of Java Naming Convention

Code like:

public class XYTest {
    static class Coords {
        int x;
        int y;

        public boolean equals(Object o) {
            Coords c = (Coords) o;
            return c.x == x && c.y == y;
        }

        public Coords(int x, int y) {
            super();
            this.x = x;
            this.y = y;
        }

        public int hashCode() {
            return new Integer(x + "0" + y);
        }
    }

    public static void main(String args[]) {

        HashMap<Coords, String> map = new HashMap<Coords, String>();

        map.put(new Coords(65, 72), "Dan");

        map.put(new Coords(68, 78), "Amn");
        map.put(new Coords(675, 89), "Ann");

        System.out.println(map.size());
    }
}

回答4:

package Lecture3;

import java.util.Scanner;

public class lecture9 {

    private int nInleste;

    public lecture9() {/*
                         * tabell/ // T/*chapter 6 in the books.
                         **/
    }

    public static void main(String[] args) {
        Scanner inn = new Scanner(System.in);
        int nInleste = 3;
        double[] tall = new double[nInleste];
        double sum = 0;
        for (int i = 0; i < nInleste; i++) {
            System.out.println("Leste en tall!");
            tall[i] = inn.nextDouble();
            sum += tall[i];
        }
        System.out.println(sum);
        double snitt = nInleste / nInleste;
        System.out.println("Gjennomsnittsverdien:" + snitt);
        for (int i = 0; i < nInleste; i++) {
            double aavik = tall[i] - snitt;
            int avvivk = 0;
            System.out.println(i + 1 + " Tal sitt avvik fra gjennomsnittet " + avvivk);

        }
    }/* end of the main methods */

}

回答5:

if you have problem with your code you can try this , simple code to store string and two int values into a map

class MyCoord{
    private int X;
    private int Y;

    public MyCoord() {
        this(0,0);
    }        
    public MyCoord(int X, int Y) {
        this.X = X;
        this.Y = Y;
    }
    public int getX() {
        return X;
    }
    public int getY() {
        return Y;
    }
    public void setX(int X) {
        this.X = X;
    }
    public void setY(int Y) {
        this.Y = Y;
    }
}

//main class begins

public class  PointDemo{
    public static void main(String[] args) {

        Map <String,MyCoord> multiplePoints=new HashMap<String, MyCoord>();
        multiplePoints.put("point1", new MyCoord(10, 20));
        multiplePoints.put("point2", new MyCoord(100, 2000));

        MyCoord coord=multiplePoints.get("point1");
        System.out.println(coord.getX() +" : "+coord.getY());              
    }
}

来源：https://stackoverflow.com/questions/11721013/store-x-and-y-coordinates

标签

java

coordinates