如何获取imageView中当前内容的相关信息并比较？

 1 public class MainActivity extends Activity implements OnClickListener{
 2 
 3     private Button button;
 4     private EditText editText;
 5     private ImageView imageView;
 6     @Override
 7     protected void onCreate(Bundle savedInstanceState) {
 8         super.onCreate(savedInstanceState);
 9         setContentView(R.layout.activity_main);
10         button = (Button) findViewById(R.id.button);
11         button.setOnClickListener(this);
12         editText = (EditText) findViewById(R.id.edit_text);
13         imageView = (ImageView) findViewById(R.id.image_view);
14     }
15         
16     @Override
17     public void onClick(View v){
18         switch(v.getId()){
19         case R.id.button:
20             Toast.makeText(MainActivity.this, editText.getText().toString(), Toast.LENGTH_LONG).show();
21             if (/*How to decide the image?*/)
22                 imageView.setImageResource(R.drawable.wa2);
23             else imageView.setImageResource(R.drawable.ic_launcher);break;
24         }
25     }

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