我开始做一个有山羊的项目！是的山羊
目前只有一个功能,当我点击一只山羊,它在随机位置创建另一只山羊.
我意识到有一种职位模式：
目前只有一个功能,当我点击一只山羊,它在随机位置创建另一只山羊.
我意识到有一种职位模式：
这是代码：
public class GameActivity extends Activity {
private int[] arrGoats = new int[5];
private RelativeLayout battlefield;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game);
battlefield = (RelativeLayout) findViewById(R.id.rel_battlefield);
arrGoats[0] = R.drawable.amarelo;
arrGoats[1] = R.drawable.azul;
arrGoats[2] = R.drawable.branco;
arrGoats[3] = R.drawable.verde;
arrGoats[4] = R.drawable.vermelho;
criarCabra(60,100);
}
private void criarCabra(float x,float y) {
int cabraImg = arrGoats[new Random().nextInt(4)];
ImageView cabra = new ImageView(this);
cabra.setImageResource(cabraImg);
cabra.setX(x);
cabra.setY(y);
LayoutParams params = (LayoutParams) new LayoutParams(MarginLayoutParams.WRAP_CONTENT,MarginLayoutParams.WRAP_CONTENT);
params.width = 150;
params.height = 120;
cabra.setLayoutParams(params);
cabra.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
criarCabra(new Random().nextInt(2000),new Random().nextInt(1000));
}
});
battlefield.addView(cabra);
}
}
我想知道为什么这个模式是创建的,尽管我使用Random().NextInt()来定义山羊的位置.
我疯了吗？
解决方法
首先,您每次都要创建一个新的Random对象.在Android中,initial seed is derived from current time and the identity hash code：
public Random() {
// Note: Using identityHashCode() to be hermetic wrt subclasses.
setSeed(System.currentTimeMillis() + System.identityHashCode(this));
}
对于按顺序创建的两个对象,身份哈希码彼此靠近.在我的Android KitKat Dalvik VM上,我得到的差异仅为32的身份哈希码.
currentTimeMillis()也不会给种子带来很大的不同.
随机本身就是linear congruential generator的形式
random[i+1] = a * random[i] + b (mod c)
其中random [0]是种子,a,b和c是参数.
基于this answer,类似的种子确实在线性同余发生器中产生类似的结果：
The reason you’re seeing similar initial output from nextDouble given similar seeds is that,because the computation of the next integer only involves a multiplication and addition,the magnitude of the next integer is not much affected by differences in the lower bits.
