Accessibility Missing contentDescription attribute on image

// warnning
private List list = new ArrayList();

// ok /put type of added object
private List<String> list = new ArrayList<String>();

        float mXDpi;
        float mYDpi;
           DisplayMetrics metrics = new DisplayMetrics();
            getWindowManager().getDefaultDisplay().getMetrics(metrics);
            mXDpi = metrics.xdpi; // The exact physical pixels per inch of the screen in the X dimension. 
            mYDpi = metrics.ydpi;
          float  mMetersToPixelsX = mXDpi / 0.0254f; // 1 inch == 0.0254 metre
          float  mMetersToPixelsY = mYDpi / 0.0254f;

import java.util.Enumeration;
import java.util.Hashtable;
public class MainClass {
	public static void main(String[] arg) {
		
		// english;germany dictionary
		String[] arrayOfString = { "one;eine", "two;zwei", "three;drei" };

	    Hashtable<String, String> hashTable = new Hashtable<String, String>();
	    for(String s: arrayOfString){
	    	String[] array = s.split(";");
	    	String sKey ="", sValue="";
	    	if(array.length > 1){
	    	sKey = array[0]; sValue = array[1];
	    		hashTable.put(sKey, sValue);
	    	}
	    }

	    Enumeration<String> enumer = hashTable.keys();
	    while (enumer.hasMoreElements()) {
	      String keyFromTable = (String) enumer.nextElement();
	      // get Returns the value to which the specified key is mapped, 
	      // or null if this map contains no mapping for the key
	      System.out.println(keyFromTable + " = " + hashTable.get(keyFromTable));
	    }       

	    
	}
}
/*
two = zwei
one = eine
three = drei
 */

public static int dpToPx(int dp)
{
    return (int) (dp * Resources.getSystem().getDisplayMetrics().density);
}

public static int pxToDp(int px)
{
    return (int) (px / Resources.getSystem().getDisplayMetrics().density);
}