从静态上下文引用的非静态方法[重复]

我有两个相同的错误,如下所示:

class FBox {//...}
class FBPlayer
{
    //Initialized instances
    FBox game = new FBox();
    **FBPillar pillar = new FBPillar();**
    **FBObjects objects = new FBObjects();**
    //Lots o Properties...

    public boolean get_Alive() { return this.b_PlayerAlive; }
    public void set_Alive(boolean alive) { this.b_PlayerAlive = alive; }

    //My Error ridden Method
    public void checkCollision()
    {
        if(get_YPos() >= **objects**.get_Ground())
                          ^My Error was incorrect name for my instance
        {
            set_Alive(false);
        }
        else if(get_Bounds().intersects(**pillar**.get_Bounds()))   
                                ^My Error was incorrect name for my instance
        {
            set_Alive(false);
        } 
    }

class FBPillar
{
    public int get_Bounds() {return 'the variable'; }
}

class FBObjects
{
    public int get_Ground() {return 'the variable'; }
}

错误出现在if语句和else if语句中 当我运行它时,它返回错误:

FBox.java:178: error: non-static method get_Bounds() cannot be referenced from a static context
               else if(get_Bounds().intersects(**FBPillar**.get_Bounds()))

if语句的错误相同,但使用FBObjects.get_Ground()) ^