从imageview传递图像到第二个活动时出错

Question

所以我有一个imageview1，当它被点击一个新的活动时，在下一个活动的相同图像显示在新的imageview2上时开始。被点击的imageview1被我的mainactivity上的listview访问。列表视图由一个数组填充，每个列表视图项都有一个相应的图像。

所以，当一个列表视图项被点击时，它开始一个新的活动imageview1驻留。该imageview使用引用可绘制图像的xml typedarray进行填充。

我无法将图像从我的第一个imageview传递到下一个新的活动。我得到一个空指针异常，我已经在下面列出了。我对编程非常陌生，我不确定如何解决这个问题。任何帮助将非常感激。

我的继承人routeDetails类，其中包含第一ImageView的

public class RouteDetails extends AppCompatActivity { 

ImageView routeImage; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_route_details); 

    //TextView for route details 
    final TextView routeDetailsView = (TextView) findViewById(R.id.routeDetailsView); 
    routeDetailsView.setText(getIntent().getExtras().getString("route")); 

    //ImageView for route details 
    routeImage = (ImageView) findViewById(R.id.routeImage); 
    routeImage.setImageResource(getIntent().getIntExtra("imageResourceId", 0)); 


    //passing image to fullscreenimage 
    routeImage.setDrawingCacheEnabled(true); 
    routeImage.buildDrawingCache(); 
    final Bitmap bitmap = routeImage.getDrawingCache(); 

////////// Trying to pass image to new activity 

    routeImage.setOnClickListener(new View.OnClickListener() { 
     public void onClick(View view) 
     { 
      Intent i = new Intent(RouteDetails.this, FullScreenImage.class); 
      //Bitmap _bitmap; // your bitmap 
      ByteArrayOutputStream _bs = new ByteArrayOutputStream(); 
      bitmap.compress(Bitmap.CompressFormat.PNG, 50, _bs); 
      i.putExtra("byteArray", _bs.toByteArray()); 
      startActivity(i); 
     } 

    }); 


//////////// 
} 

和我的继承人fullscreenimage类即时通讯试图将图像传递到

public class FullScreenImage extends AppCompatActivity { 

TouchImageView routeImageFull; 

@Override 
protected void onCreate(Bundle saveInstanceState){ 
    super.onCreate(saveInstanceState); 


    setContentView(R.layout.full_screen_image); 
    routeImageFull = (TouchImageView) findViewById(R.id.fullScreenImageView); 


    if(getIntent().hasExtra("byteArray")) { 
     TouchImageView routeImageFull= new TouchImageView(this); 
     Bitmap bitmap = BitmapFactory.decodeByteArray(
       getIntent().getByteArrayExtra("byteArray"),0,getIntent().getByteArrayExtra("byteArray").length); 
     routeImageFull.setImageBitmap(bitmap); 
    } 
} 
} 

和继承人的错误即时得到

E/AndroidRuntime: FATAL EXCEPTION: main 
       Process: com.example.zach.listview, PID: 3429 
       java.lang.NullPointerException: Attempt to invoke virtual  method 'boolean  android.graphics.Bitmap.compress(android.graphics.Bitmap$CompressFormat, int,  java.io.OutputStream)' on a null object reference 
        at  com.example.zach.listview.RouteDetails$1.onClick(RouteDetails.java:47) 
        at android.view.View.performClick(View.java:5610) 
        at android.view.View$PerformClick.run(View.java:22265) 
        at android.os.Handler.handleCallback(Handler.java:751) 
        at android.os.Handler.dispatchMessage(Handler.java:95) 
        at android.os.Looper.loop(Looper.java:154) 
        at  android.app.ActivityThread.main(ActivityThread.java:6077) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 

Answer 1

而不是传递整个位图。您可以简单地将您在此处获得的资源ID发送给其他活动，并且可以通过相同的方式显示图像，您在此处执行操作。以下是更改后的代码。

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_route_details); 

    //TextView for route details 
    final TextView routeDetailsView = (TextView)  
    findViewById(R.id.routeDetailsView); 
    routeDetailsView.setText(getIntent().getExtras().getString("route")); 

    //ImageView for route details 
    routeImage = (ImageView) findViewById(R.id.routeImage); 

    int mImageResource = getIntent().getIntExtra("imageResourceId", 0); 
    routeImage.setImageResource(mImageResource); 


    //passing image to fullscreenimage 
    routeImage.setDrawingCacheEnabled(true); 
    routeImage.buildDrawingCache(); 
    final Bitmap bitmap = routeImage.getDrawingCache(); 

    // Trying to pass image to new activity 

    routeImage.setOnClickListener(new View.OnClickListener() { 
     public void onClick(View view) 
     { 
      Intent i = new Intent(RouteDetails.this,FullScreenImage.class); 
      i.putExtra("mImageResource", mImageResource); 
      startActivity(i); 
     } 

    }); 
}