android - How to disable Button if EditText is empty ?

Question

I have an EditText and a Button in my application.

When the button is clicked,the text entered in the EditText is added to a ListView.

I want to disable the Button if the EditText is empty.How to do this ?

This is my code for button click

ImageButton imb=(ImageButton)findViewById(R.id.btn_send);
            imb.setOnClickListener(new OnClickListener()
            {
             @Override
             public void onClick(View arg0) 
             { 
                 EditText et = (EditText)findViewById(R.id.EditText1);

                  String str = et.getText().toString();
                  web1.add(str);
                  Toast.makeText(ShoutSingleProgram.this, "You entered...."+str, Toast.LENGTH_SHORT).show();
                  adapter1.notifyDataSetChanged();
                  et.setText("");

                    }
            });
            }

How can i do this ?

Answer 1

    editText1.addTextChangedListener(new TextWatcher() {

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {

           if(s.toString().trim().length()==0){
                button.setEnabled(false);
              } else {
                button.setEnabled(true);
              }
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {
            // TODO Auto-generated method stub

        }

        @Override
        public void afterTextChanged(Editable s) {
            // TODO Auto-generated method stub

        }
    });