title: ImageButton.setEnabled() throws Exception
body: <p>A newbie here in Android/Java but well founded in C/C++ &amp; Object Pascal. I have 5 ImageButtons with only one enabled. Then at some point in time when the lone enabled button is pressed, the other four are supposed to be enabled too by calling setEnabled() passed with the boolean values ( enableBtn2..3.. etc). But whenever I press the lone enabled button to call the member newRung() which in turn calls  another member  refreshMnuButtons(),the exception is raised which I suspect originated by the call to the setEnabled() parent class member.Can someone pls. point out  the loophole? I frantically searched for the explanation but I can't seem to find the appropriate answer. Kindly see my code attached: </p>
  
  <pre><code>public class MyActivity extends Activity {
      private ImageView cell1,cell2,cell3,cell4,cell5,cell6,rungClose;
      private ImageButton mnuBtn1,mnuBtn2,mnuBtn3,mnuBtn4,mnuBtn5;
      private boolean enableBtn1 = true,
              enableBtn2 = false,
              enableBtn3 = false,
              enableBtn4 = false,
              enableBtn5 = false;
  
      @Override
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_pic_ladder_main);
  
          // setup toolbar
          TableLayout tbl = (TableLayout)findViewById(R.id.tblToolbar);
          ImageButton mnuBtn1 = new ImageButton(this);
  
          mnuBtn1.setImageResource(R.drawable.rungopentool);
          mnuBtn1.setEnabled(enableBtn1);
          //setup mnuBtn1 listener
  
          mnuBtn1.setOnClickListener(new View.OnClickListener() {
              @Override   
              public void onClick(View view) {
                  newRung();
              }
          });
          ImageButton mnuBtn2 = new ImageButton(this);
  
          mnuBtn2.setImageResource(R.drawable.noc);
          mnuBtn2.setEnabled(enableBtn2);
          //setup mnuBtn2 listener
  
          mnuBtn2.setOnClickListener(new View.OnClickListener() {
              @Override   
              public void onClick(View view) {
                  addNOC();
              }
          });
          final ImageButton mnuBtn3 = new ImageButton(this);
  
          mnuBtn3.setImageResource(R.drawable.ncc); 
          mnuBtn3.setEnabled(enableBtn3);
          //setup mnuBtn3 listener
  
          mnuBtn3.setOnClickListener(new View.OnClickListener() {
              @Override   
              public void onClick(View view) {
                  addNCC();
              }
          });
          ImageButton mnuBtn4 = new ImageButton(this);
  
          mnuBtn4.setImageResource(R.drawable.process);
          mnuBtn4.setEnabled(enableBtn4);
          //setup mnuBtn4 listener
  
          mnuBtn4.setOnClickListener(new View.OnClickListener() {
              @Override   
              public void onClick(View view) {
                  addProcess();
              }
          });
          ImageButton mnuBtn5 = new ImageButton(this);
  
          mnuBtn5.setImageResource(R.drawable.coil);
          mnuBtn5.setEnabled(enableBtn5);
          //setup mnuBtn5 listener
  
          mnuBtn5.setOnClickListener(new View.OnClickListener() {
              @Override   
              public void onClick(View view) {
                  addCoil();
              }
          });
  
          TableRow  mnurow = new TableRow(this);
          mnurow.setBackgroundColor(0x3F000000);
  
          // display menu
          mnurow.addView(mnuBtn1); 
          mnurow.addView(mnuBtn2);
          mnurow.addView(mnuBtn3); 
          mnurow.addView(mnuBtn4); 
          mnurow.addView(mnuBtn5);
  
          tbl.addView(mnurow); 
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          getMenuInflater().inflate(R.menu.activity_pic_ladder_main, menu);
          return true;
      }
  
      private  void  createRungImages() {
          // TODO
      }
  
      private void newRung()
      {
          Toast.makeText(this, "New Rung" ,Toast.LENGTH_SHORT).show();
          enableBtn2 = true;
          enableBtn3 = true;
          enableBtn4 = true;
          enableBtn5 = true;
          enableBtn1 = false;
          refreshMnuButtons();
      }
      private void addNOC()
      {
          Toast.makeText(this, "NOC" ,Toast.LENGTH_SHORT).show();
      }
      private void addNCC()
      {
          Toast.makeText(this, "NCC" ,Toast.LENGTH_SHORT).show();
      }
      private void addProcess()
      {
          Toast.makeText(this, "Add Process" ,Toast.LENGTH_SHORT).show();
      }
      private void addCoil()
      {
          Toast.makeText(this, "Coil" ,Toast.LENGTH_SHORT).show();
      }
  
      public void refreshMnuButtons()
      {
          try {  
              mnuBtn1.setEnabled(enableBtn1);
              mnuBtn2.setEnabled(enableBtn2);
              mnuBtn3.setEnabled(enableBtn3);
              mnuBtn4.setEnabled(enableBtn4);
              mnuBtn5.setEnabled(enableBtn5);
          }
          catch(Exception e) {Toast.makeText(this, "Exception" ,Toast.LENGTH_SHORT).show(); }
      }
  }
  </code></pre>
  
  <p>Here's my xml: Please note that I'm trying to generate most of the graphic elements by code.</p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent" &gt;
  
      &lt;RelativeLayout
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:layout_alignParentBottom="false"
          android:layout_alignParentTop="true"
          android:layout_centerHorizontal="true"
          android:layout_marginBottom="44dp" &gt;
  
          &lt;ScrollView
              android:id="@+id/scrollView1"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content" &gt;
  
              &lt;TableLayout
                  android:id="@+id/ladderSheet"
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content" &gt;
  
              &lt;/TableLayout&gt;
  
          &lt;/ScrollView&gt;
  
      &lt;/RelativeLayout&gt;
  
      &lt;RelativeLayout
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:layout_alignParentBottom="true" &gt;
  
         &lt;HorizontalScrollView
             android:id="@+id/horizontalScrollView1"
             android:layout_width="fill_parent"
             android:layout_height="wrap_content" &gt;
  
             &lt;TableLayout
                 android:id="@+id/tblToolbar"
                 android:layout_width="fill_parent"
                 android:layout_height="wrap_content"
                 android:scrollbarStyle="outsideInset"
                 android:scrollbars="horizontal" &gt;
             &lt;/TableLayout&gt;
  
         &lt;/HorizontalScrollView&gt;
  
      &lt;/RelativeLayout&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>Thanks in advance!</p>