WTF 3D matrix!?

/**
 *
 * @author PiMaster
 */

package bloxpedition;

import java.util.ArrayList;
import java.util.List;

public class Matrix<T>{
    private List<T> data;
    private int width;
    private int length;
    private int height;

    Matrix(int w,int h,int l){
        resize(w,h,l);
    }

    T get(int x,int y,int z){
        if(x>=width){
            throw new IndexOutOfBoundsException("x greater than or equal to width");}
        if(z>=length){
            throw new IndexOutOfBoundsException("z greater than or equal to length");}
        if(y>=height){
            throw new IndexOutOfBoundsException("y greater than or equal to height");}
        return data.get(z*width*height+y*width+x);
    }

    void set(int x,int y,int z,T value){
        if(x>=width){
            throw new IndexOutOfBoundsException("x greater than or equal to width");}
        if(z>=length){
            throw new IndexOutOfBoundsException("z greater than or equal to length");}
        if(y>=height){
            throw new IndexOutOfBoundsException("y greater than or equal to height");}
        data.set(z*width*height+y*width+x,value);
    }

    void resize(int w,int l,int h){
        if(w<=0 || h<=0 || l<=0){
            throw new IllegalArgumentException("Passed dimension <=0");}
        width=w;
        length=l;
        height=h;
        System.out.println("Calculated size:"+width*length*height);
        data=new ArrayList<T>(width*length*height);
        System.out.println("Size:"+data.size());
    }

    int get_size(){
        return data.size();
    }

    int get_width(){
        return width;
    }

    int get_length(){
        return length;
    }

    int get_height(){
        return height;
    }
}