Android，从不同的活动保存和加载缓存中的位图

Question

我有我需要在新活动中显示的位图，所以我cahe它和在打开的活动中，我尝试加载它，但我得到一个nullPointerException。在这里，我保存图片：

File cacheDir = getBaseContext().getCacheDir(); 
File f = new File(cacheDir, "pic"); 

try { 
    FileOutputStream out = new FileOutputStream(
      f); 
    pic.compress(
      Bitmap.CompressFormat.JPEG, 
      100, out); 
    out.flush(); 
    out.close(); 

} catch (FileNotFoundException e) { 
    e.printStackTrace(); 
} catch (IOException e) { 
    e.printStackTrace(); 
} 

Intent intent = new Intent(
     AndroidActivity.this, 
     OpenPictureActivity.class); 
startActivity(intent); 

，然后在新的活动我尝试打开它：

public void onCreate(Bundle icicle) { 
    super.onCreate(icicle); 

    File cacheDir = getBaseContext().getCacheDir(); 
    File f = new File(cacheDir, "pic");  
    FileInputStream fis = null; 
    try { 
     fis = new FileInputStream(f); 
    } catch (FileNotFoundException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
    Bitmap bitmap = BitmapFactory.decodeStream(fis); 

    ImageView viewBitmap = (ImageView) findViewById(R.id.icon2); 
    viewBitmap.setImageBitmap(bitmap); 
    setContentView(R.layout.open_pic_layout); 

Answer 1

只是检查你的代码：

ImageView viewBitmap = (ImageView) findViewById(R.id.icon2); 
viewBitmap.setImageBitmap(bitmap); 
setContentView(R.layout.open_pic_layout); 

你已经写了findViewById（）在设置内容视图之前。这是不对的。

public void onCreate(Bundle icicle) { 
    super.onCreate(icicle); 
    setContentView(R.layout.open_pic_layout); 

    // do your operations here 
    }