java - 减少和增加 float 增量android

Question

我正在尝试通过屏幕按钮增大和减小音量。我这里有代码:

//variables
float leftVolume = 0.5f;
float rightVolume = 0.5f;

public void lowerVolume(View view)
{ float decrement = 0.2f;
    rightVolume -= decrement;
    leftVolume -= decrement;
    Log.d("Values","This is the value of volume"+ leftVolume);
}

public void raiseVolume(View view)
{ float increment = 0.2f;
    rightVolume = ++increment;
    leftVolume = ++increment;
    Log.d("Values","This is the value of volume"+ rightVolume);
}

日志显示了一些疯狂的值，例如当我单击 rasieVolume 时，它​​会变为 1.2f 并保持在那里。

Answer 1

发生这种情况是因为您每次调用 raiseVolume() 时都将浮点值设置为 1.2 。

public void raiseVolume(View view)
{ float increment = 0.2f; //you set increment here
    rightVolume = ++increment; //then simply increase it by 1
    leftVolume = ++increment;

    //...and so your volume will always be 1.2 at this point
    Log.d("Values","This is the value of volume"+ rightVolume);
}

解决这个问题的方法是将音量设置为raiseVolume()之外的初始值。方法(您已经这样做了)，然后在 raiseVolume() 内增加它方法。

像这样:

//variables
float leftVolume = 0.5f;
float rightVolume = 0.5f;

public void raiseVolume(View view)
{ float increment = 0.2f;
    rightVolume += increment; //change this line to this
    leftVolume += increment;  //change this line to this
    Log.d("Values","This is the value of volume"+ rightVolume);
}