Axis Aligned Bounding Box - Anything missing or wrong?

AABB.java

package net.lomeli.savetown.util.math;

public class AABB {
    public static final AABB ZERO_BOX = new AABB(0, 0, 0, 0);
    private float x1, x2, y1, y2;

    public AABB(float x1, float x2, float y1, float y2) {
        this.x1 = x1;
        this.x2 = x2;
        this.y1 = y1;
        this.y2 = y2;
    }

    public AABB expand(float xChange, float yChange) {
        float newX1 = this.x1 - xChange;
        float newX2 = this.x2 + xChange;
        float newY1 = this.y1 - yChange;
        float newY2 = this.y2 + yChange;
        return new AABB(newX1, newX2, newY1, newY2);
    }

    public AABB expand(float change) {
        return expand(change, change);
    }

    public boolean doBoxesCollide(float x1, float x2, float y1, float y2) {
        return !(this.x2 < x1 || x2 < this.x1 || this.y2 < y1 || y2 < this.y1);
    }

    public boolean doBoxesCollide(AABB box) {
        return doBoxesCollide(box.getX1(), box.getX2(), box.getY1(), box.getY2());
    }

    public void translateBox(float xChange, float yChange) {
        this.x1 += xChange;
        this.x2 += xChange;
        this.y1 += yChange;
        this.y2 += yChange;
    }

    public void setPosition(float x, float y) {
        float xDif = this.x2 - this.x1;
        float yDif = this.y2 - this.y2;
        this.x1 = x;
        this.y1 = y;
        this.x2 = x + xDif;
        this.y2 = y + yDif;
    }

    public float getX1() {
        return x1;
    }

    public float getX2() {
        return x2;
    }

    public float getY1() {
        return y1;
    }

    public float getY2() {
        return y2;
    }
}