定义泛型数组，怎么创建一个已知大小的二维数组

Z时代
2024-01-10
分类：技术分享

图片说明

import java.lang.reflect.Array;
/**
* A 2D cartesian plane implemented as with an array. Each (x,y) coordinate can
* hold a single item of type <T>.
*
* @param <T> The type of element held in the data structure
*/
public class ArrayCartesianPlane<T> implements CartesianPlane<T> {
private int minimumX;
private int maximumX;
private int minimumY;
private int maximumY;
private T[][] list;
/**
* Constructs a new ArrayCartesianPlane object with given minimum and
* maximum bounds.
*
* Note that these bounds are allowed to be negative.
*
* @param minimumX A new minimum bound for the x values of
*         elements.
* @param maximumX A new maximum bound for the x values of
*         elements.
* @param minimumY A new minimum bound for the y values of
*         elements.
* @param maximumY A new maximum bound for the y values of
*         elements.
* @throws IllegalArgumentException if the x minimum is greater
*         than the x maximum (and resp. with y min/max)
*/
public ArrayCartesianPlane(int minimumX, int maximumX, int minimumY,
int maximumY) throws IllegalArgumentException {
// TODO: implement the constructor
this.minimumX = minimumX;
this.minimumY = minimumY;
this.maximumX = maximumX;
this.maximumY = maximumY;
this.list = new T[maximumX-minimumX][maximumY-minimumY];
}
/**
* Add an element at a fixed position, overriding any existing element
* there.
*
* @param x       The x-coordinate of the element's position
* @param y       The y-coordinate of the element's position
* @param element The element to be added at the indicated
*                position
* @throws IllegalArgumentException If the x or y value is out of
*                                  the grid's minimum/maximum bounds
*/
@Override
public void add(int x, int y, T element) throws IllegalArgumentException {
list[x][y] = element;
}
/**
* Returns the element at the indicated position.
*
* @param x The x-coordinate of the element to retrieve
* @param y The y-coordinate of the element to retrieve
* @return The element at this position, or null is no elements exist
* @throws IndexOutOfBoundsException If the x or y value is out of
*                                   the grid's minimum/maximum bounds
*/
@Override
public T get(int x, int y) throws IndexOutOfBoundsException {
return (T)(list[x][y]);
}
/**
* Removes the element at the indicated position.
*
* @param x The x-coordinate of the element to remove
* @param y The y-coordinate of the element to remove
* @return true if an element was successfully removed, false if no element
* exists at (x, y)
* @throws IndexOutOfBoundsException If the x or y value is out of
*                                   the grid's minimum/maximum bounds
*/
@Override
public boolean remove(int x, int y) throws IndexOutOfBoundsException {
if (list[x][y] == 0) {
return false;
}
}
/**
* Removes all elements stored in the grid.
*/
@Override
public void clear() {
}
/**
* Changes the size of the grid. Existing elements should remain at the
* same (x, y) coordinate If a resizing operation has invalid dimensions or
* causes an element to be lost, the grid should remain unmodified and an
* IllegalArgumentException thrown
*
* @param newMinimumX A new minimum bound for the x values of
*                    elements.
* @param newMaximumX A new maximum bound for the x values of
*                    elements.
* @param newMinimumY A new minimum bound for the y values of
*                    elements.
* @param newMaximumY A new maximum bound for the y values of
*                    elements.
* @throws IllegalArgumentException if the x minimum is greater
*                                  than the x maximum (and resp. with y min/max) or if an element
*                                  would be lost after this resizing operation
*/
@Override
public void resize(int newMinimumX, int newMaximumX, int newMinimumY, int newMaximumY) throws IllegalArgumentException {
}
// TODO: you are to implement all of ArrayCartesianPlanes's methods here
}

回答

public class Text {
    public static void main(String[ ] args) {
        Test test = new Test(4,3,2,1);
        System.out.println(test.getList().length);
        System.out.println(test.getList()[0].length);
    }
}
class Test{
    private int minX;
    private int minY;
    private int maxX;
    private int maxY;
    private T[][] list;
    public Test(int minX, int minY, int maxX, int maxY) {
        this.minX = minX;
        this.minY = minY;
        this.maxX = maxX;
        this.maxY = maxY;
        this.list = new T[minX-minY][maxX-maxY];
    }
}
结果
1
1
Process finished with exit code 0