java - 绿脚：跳跃和回来是行不通的

Question

玩家跳了但没有回来，如果你按住向上箭头键，玩家会飞/漂浮，我该如何解决这个问题让玩家回落？如果提供源代码会很好，但任何帮助都很棒。

import greenfoot.*; 

public class Character extends Actor
{
double Force = 0;
double Gravity = 0.5;
double Boost_Speed = -6;
int Wait = 0;

public void act() 
{
    setLocation( getX(), (int)(getY() + Force) );
    if(Greenfoot.isKeyDown("up")){
        Wait++;
        Force = Boost_Speed;
        if(Wait >= 8)
        {   
            setLocation( getX(), (int)(getY() + 1) );
            Wait = 0;
        } 
    }
    Force = Force + Gravity;
} 

}

Answer 1

我建议通过引入标志isJumped并使用 Greenfoot.getKey() 方法按下最后一个键来建议解决方案：

import greenfoot.*; 

public class Character extends Actor
{
double Force = 0;
double Gravity = 0.5;
double Boost_Speed = -6;
int Wait = 0;
private String lastKey;
private Boolean isJumped = false;
public void act() 
{
    setLocation( getX(), (int)(getY() + Force) );
    lastKey = Greenfoot.getKey();
    if(lastKey!=null && lastKey.equals("up") == true && isJumped == true) {
        isJumped = false;
    }
    if(Greenfoot.isKeyDown("up") == true && isJumped == false) {
        isJumped = true;
         Wait++;
        Force = Boost_Speed;
        if(Wait >= 8)
        {   
            setLocation( getX(), (int)(getY() + 1) );
            Wait = 0;
        } 
    }
    Force = Force + Gravity;
} 
}