由网友(喵爱)分享简介：我试着去覆盖使用下面的方法在画布上的图像：Im trying to overlay images on a canvas using the following method:private Bitmap overlay(Bitmap bmp1, Bitmap bmp2) {bmOverlay = Bitmap.c...

我试着去覆盖使用下面的方法在画布上的图像：

Im trying to overlay images on a canvas using the following method:

private Bitmap overlay(Bitmap bmp1, Bitmap bmp2) {

    bmOverlay = Bitmap.createBitmap(70, 70, Bitmap.Config.RGB_565);
    canvas = new Canvas(bmOverlay);
    canvas.drawBitmap(bmp1, 0, 0, null);  //line 179
    canvas.drawBitmap(bmp2, 0, 0, null);
    return bmOverlay;           
}

不过，我的应用程序不断崩溃和日志记载：

However, my app keeps crashing and the log reads:

显示java.lang.NullPointerException     在android.graphics.Canvas.throwIfRecycled（Canvas.java:954）     在android.graphics.Canvas.drawBitmap（Canvas.java:980）     在com.MyApp.overlay（MyApp.java:179）

java.lang.NullPointerException at android.graphics.Canvas.throwIfRecycled(Canvas.java:954) at android.graphics.Canvas.drawBitmap(Canvas.java:980) at com.MyApp.overlay(MyApp.java:179)

谁能帮助？

推荐答案

我有同样的trowIfRecycled例外，而试图绘制一个位图的画布。我试图在一个线程我开始画，该方案得到周围初始化前位。所以，在我的情况：位为空，我不得不找一个更好的地方做初始化。

I had the same trowIfRecycled exception while trying to draw a bitmap to a canvas. I was trying to draw in a thread I started, before the program got around to initializing the bitmap. So in my case: bitmap was null and I had to look for a better place to do the initializing.