Difference between “@+id/” and “@id/” in Android

<com.google.android.gms.ads.AdView
    xmlns:ads="//schemas.android.com/apk/res-auto"
    android:id="@+id/adView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    ads:adUnitId="MY_AD_UNIT_ID"
    ads:adSize="BANNER"/>

// onResume
AdView adView = (AdView)this.findViewById(R.id.adView);
AdRequest adRequest = new AdRequest.Builder()
    .addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
    .addTestDevice("TEST_DEVICE_ID")
    .build();
adView.loadAd(adRequest);

// layout in xml file
    <LinearLayout
        android:id="@+id/layout"
              android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

// java class with fragment in Fragment class or in Activity class
private static AdView adView;
        @Override
		public void onResume(){  
                super.onResume();
                 try {
                	 // in xml is empty layout
					adView = new AdView(getActivity());
					adView.setAdUnitId("ca-app-pub-626/638103xxxxxxx");
					adView.setAdSize(AdSize.BANNER);  
					
                	                LinearLayout layout = (LinearLayout)getView() .findViewById(R.id.layout);
					layout.addView(adView);
					
					AdRequest adRequest = new AdRequest.Builder().build();   
					adView.loadAd(adRequest);

				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
        }

import java.util.Comparator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;

public class MainClass {
	public static void main(String[] arg) {

		// english;germany dictionary
		String[] arrayOfString = { "one;eine", "two;zwei", "three;drei",
				"four;vier" };

		Map<String, String> map = new TreeMap<String, String>();

		for (String s : arrayOfString) {
			String[] array = s.split(";");
			String sKey = "", sValue = "";
			if (array.length > 1) {
				sKey = array[0];
				sValue = array[1];
				map.put(sKey, sValue);
			}
		}
		for (Entry<String, String> entry: mapSortedByValues(map)) {
		    System.out.println(entry.getKey() + " = " + entry.getValue());
		}
	}

	static <K, V extends Comparable<? super V>> SortedSet<Map.Entry<K, V>> mapSortedByValues(
			Map<K, V> map) {
		SortedSet<Map.Entry<K, V>> sortedSetOfEntries = new TreeSet<Map.Entry<K, V>>(
				new Comparator<Map.Entry<K, V>>() {
					@Override
					public int compare(Map.Entry<K, V> entry_1, Map.Entry<K, V> entry_2) {
						int res = entry_1.getValue().compareTo(entry_2.getValue());
						return res != 0 ? res : 1; 
						// return entry_1.getValue().compareTo(entry_2.getValue());							
					}
				});
		sortedSetOfEntries.addAll(map.entrySet());
		return sortedSetOfEntries;
	}
}
/*
three = drei
one = eine
four = vier
two = zwei
 */

   	BitmapFactory.Options options = new BitmapFactory.Options();
        // If set to true, the decoder will return null (no bitmap), but the out... fields will still
        // be set, allowing the caller to query the bitmap without having to allocate the memory for its pixels. 
    	options.inJustDecodeBounds = true; 
    	BitmapFactory.decodeResource(getResources(), R.drawable.my_image, options);
    	int imageHeight = options.outHeight; // 1024
    	int imageWidth = options.outWidth; // 860
    	String imageType = options.outMimeType; // .jpg .png .gif
 

    float density = getResources().getDisplayMetrics().density;

    Debug.MemoryInfo memoryInfo = new Debug.MemoryInfo();
    Debug.getMemoryInfo(memoryInfo);
    final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
    final int freeMemory = (int) (Runtime.getRuntime().freeMemory() / 1024);
    String memMessage = String.format(
        "Free=%d kB,

MaxMem=%d kB,

 Memory: Pss=%.2f MB, Private=%.2f MB, Shared=%.2f MB",
        freeMemory,
        maxMemory,
        memoryInfo.getTotalPss() / 1024.0,
        memoryInfo.getTotalPrivateDirty() / 1024.0,
        memoryInfo.getTotalSharedDirty() / 1024.0);
    ((TextView)findViewById(R.id.textViewInfo)).setText(memMessage );

create div with class with name e.g. circle


create in styleSheet.css class circle

 <div class="circle" id="">3</div>

.circle {
 border-radius: 50%;
    width: 50px;
    height: 50px;
    background: yellow;
    position: absolute;
    display: block;
    border: 6px solid blue;
    font-size: 50px;
    text-align: center;
}

// solution 1
ImageView imageView = (ImageView)findViewById(R.id.myimage);
imageView.setImageDrawable(null);
// or
imageView.setImageResource(0);

// solution 2  hide ImageView
imageView.setVisibility(View.INVISIBLE);

// solution 3 resize ImageView 0, 0
 hImageViewSemafor.setLayoutParams(new LinearLayout.LayoutParams(0,0));