你好，
我是Android的新手，我正在开发一个简单的图片库。我将照片变成 public class buttonActionStart implements ActionListener { // overwritten ActionListener
public void actionPerformed (ActionEvent e){
JFrame window2 = new JFrame("Main Game"); //create empty frame
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
window2.setSize(screenSize.width,screenSize.height);
window2.add(new JPanel(){
public void paintComponent(Graphics graph){
super.paintComponent(graph);
Board board = new Board();
graph.drawString(board.sqaures[1].getName(),440,560);
graph.drawString(board.sqaures[2].getName(),335,560);
graph.drawString(board.sqaures[3].getName(),225,560);
graph.drawString(board.sqaures[4].getName(),145,560);
graph.drawString(board.sqaures[5].getName(),30,560);
graph.drawString(board.sqaures[6].getName(),25,460);
graph.drawString(board.sqaures[7].getName(),25,360);
graph.drawString(board.sqaures[8].getName(),35,260);
graph.drawString(board.sqaures[9].getName(),25,160);
graph.drawString(board.sqaures[10].getName(),25,60);
graph.drawString(board.sqaures[11].getName(),140,60);
graph.drawString(board.sqaures[12].getName(),240,60);
graph.drawString(board.sqaures[13].getName(),340,60);
graph.drawString(board.sqaures[14].getName(),440,60);
graph.drawString(board.sqaures[15].getName(),530,60);
graph.drawString(board.sqaures[16].getName(),550,160);
graph.drawString(board.sqaures[17].getName(),545,260);
graph.drawString(board.sqaures[18].getName(),540,360);
graph.drawString(board.sqaures[19].getName(),550,460);
for (int i = 0; i < 6; i++)
graph.drawRect(10 + (i*100),10,100,100);
for (int j = 0; j < 4; j++)
graph.drawRect(10,110 + (j*100),100,100);
for (int k = 0; k < 4; k++)
graph.drawRect(510,110 + (k*100),100,100);
for (int l = 0; l < 6; l++)
graph.drawRect(10 + (l*100),510,100,100);
InputStream resource = UI.class.getResourceAsStream("player1.png");
Image player1Image = null;
try{
player1Image = ImageIO.read(resource);
}catch (IOException e){
e.printStackTrace();
}
resource = UI.class.getResourceAsStream("player2.png");
Image player2Image = null;
try{
player2Image = ImageIO.read(resource);
}catch (IOException e){
e.printStackTrace();
}
resource = UI.class.getResourceAsStream("player3.png");
Image player3Image = null;
try{
player3Image = ImageIO.read(resource);
}catch (IOException e){
e.printStackTrace();
}
resource = UI.class.getResourceAsStream("player4.png");
Image player4Image = null;
try{
player4Image = ImageIO.read(resource);
}catch (IOException e){
e.printStackTrace();
}
graph.drawImage(player1Image, 511, 511, null);
graph.drawImage(player2Image, 585, 510, null);
graph.drawImage(player3Image, 511, 585, null);
graph.drawImage(player4Image, 585, 585, null);
}
});
window2.setVisible(true);
}
}
，然后将其剪切成9个方形（或相等）元素。之后，我使用我的Bitmap版本将其放入GridView。最后我想做一个效果，这个正方形随机变得透明（从可见到透明的渐变）并在它们下面再渲染另一个图像（所以这个过程可以无限重复）。我想稍后更改照片ImageAdapter，但现在我无法弄清楚如何使OnClick的某些元素透明。我尝试使用GridView或getChildAt(int index)，但我得到的只是getItemAtPosition(int position)。谁能帮我这个？我尝试在网络上使用许多代码示例，但没有一个能够实现。
我的主要活动：
NullPointerException
我的适配器：
public class MainActivity extends AppCompatActivity {
private int screenX;
private int screenY;
private ArrayList<Bitmap> chunkedImages;
private GridView gv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
RelativeLayout rl = (RelativeLayout)findViewById(R.id.RelativeLayout1);
rl.setBackgroundColor(Color.BLACK);
loadScreenXY();
ImageView view = new ImageView(this);
view.setImageResource(R.drawable.pizza);
this.chunkedImages = this.splitImage(view,9);
gv = (GridView) findViewById(R.id.GridView);
gv.setAdapter(new GridImageAdapter(this,this.chunkedImages));
gv.setNumColumns(3);
}
private void loadScreenXY() {
Display display = getWindowManager().getDefaultDisplay();
Point size = new Point();
display.getSize(size);
this.screenX = size.x;
this.screenY = size.y;
}
private ArrayList<Bitmap> splitImage(ImageView image, int chunkNumbers) {
int rows,cols;
int chunkHeight;
int chunkWidth;
ArrayList<Bitmap> chunkedImages = new ArrayList<Bitmap>(chunkNumbers);
BitmapDrawable drawable = (BitmapDrawable) image.getDrawable();
Bitmap bitmap = drawable.getBitmap();
rows = cols = (int) Math.sqrt(chunkNumbers);
chunkHeight = bitmap.getHeight()/rows;
chunkWidth = bitmap.getWidth()/cols;
int yCoord = 0;
for(int x=0; x<rows; x++){
int xCoord = 0;
for(int y=0; y<cols; y++){
chunkedImages.add(Bitmap.createBitmap(bitmap, xCoord, yCoord, chunkWidth, chunkHeight));
xCoord += chunkWidth;
}
yCoord += chunkHeight;
}
return chunkedImages;
}