android – How to disable Button if EditText is empty ?-ThrowExceptions

Exception or error:

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 ?

How to solve:
    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

        }
    });

###

Use TextChangedListener and initially disable ImageButton in onCreate().

Try this

public class MyActivity extends Activity {

ImageButton imb;
EditText et;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    imb = (ImageButton) findViewById(R.id.btn_send);
    et = (EditText) findViewById(R.id.EditText1);

    imb.setEnabled(false); // set button disable initially

    et.addTextChangedListener(new TextWatcher() {

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

            if (s.toString().equals("")) {
                imb.setEnabled(false);
            } else {
                imb.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

        }
    });

}

}

###

Simple just check the condition in onCreate

if (et.getText().toString().trim().equals("")){
  button.setEnabled(false);
}
else{
button.setEnabled(true);
}

###

I used TextUtils for a concise solution:

    editText.addTextChangedListener(new TextWatcher() {
        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            button.setEnabled(!TextUtils.isEmpty(s.toString().trim()));
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        }

        @Override
        public void afterTextChanged(Editable s) {
        }
    });

###

Easy Solution

This is very easy to implement in Data-Binding. I hope you are aware of it at this time. You can manage Button with EditText via only XML.

android:enabled="@{etName.text.length() > 0 && etPassword.text.length() > 5}"

Which is equivalent to

button.setEnabled(etName.getText().length() > 0 && etPassword.getText().length() > 5 );
  • Here & is HTML entity which denotes to &. There can be any operator like &.

  • etName & etPassword are EditTexts ids.

Complete XML –

<LinearLayout
    >

    <EditText
        android:id="@+id/etName"
        />

    <EditText
        android:id="@+id/etPassword"
        />

    <Button
        android:enabled="@{etName.text.length() > 5 &amp;&amp; etPassword.text.length() > 5}"
        />

</LinearLayout>

###

Add a TextWatcher to your EditText, so that when you change the text inside it, you Button enables or disables itself.

###

Initally in onCreate() disable the button.
Then add a addTextChangedListenerto the edit text. within that check the edittext length and disable if it is 0 or otherwise enable it

###

Here’s a super simple answer in Kotlin.

Just replace ‘EditText’ and ‘Button’ with your own.

Button.isEnabled = false
        EditText.addTextChangedListener(object: TextWatcher {
            override fun onTextChanged(s:CharSequence, start:Int, before:Int, count:Int) {
                Button.isEnabled = s.toString().trim{ it <= ' ' }.isNotEmpty()
            }
            override fun beforeTextChanged(s:CharSequence, start:Int, count:Int,
                                           after:Int) {
            }
            override fun afterTextChanged(s: Editable) {
            }
        })

For Multiple EditTexts go

Button.isEnabled = false
            val editTexts = listOf(editText1, editText2, editText3, editText4, editText5, editText6)
for (editText in editTexts) {
            editText.addTextChangedListener(object : TextWatcher {
            override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
                var et1 = editText1.text.toString().trim()
                var et2 = editText2.text.toString().trim()
                var et3 = editText3.text.toString().trim()
                var et4 = editText4.text.toString().trim()
                var et5 = editText5.text.toString().trim()
                var et6 = editText6.text.toString().trim()

                computeBtn.isEnabled = et1.isNotEmpty()
                        && et2.isNotEmpty()
                        && et3.isNotEmpty()
                        && et4.isNotEmpty()
                        && et5.isNotEmpty()
                        && et6.isNotEmpty()
            }

            override fun beforeTextChanged(
                s: CharSequence, start: Int, count: Int, after: Int) {
            }

            override fun afterTextChanged(
                s: Editable) {
            }
        })
        }

###

on Oncreate() , before button click you should check the condition as,

   ImageButton imb=(ImageButton)findViewById(R.id.btn_send);
   EditText et = (EditText)findViewById(R.id.EditText1);
   if(et.getText().toString().equals("")
   {
   imb.setEnabled(false);
   }

   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("");

                }
        });

###

When you want to disable the editText there You will use below code

editText.setEnabled(false); 
editText.setFocusable(false);

###

you check the status of an edittext at runtime using the text watcher.
the below code counts the text length and disables if the length is zero.
use this code:

EditText mEditText = new EditText(this);
    mEditText.addTextChangedListener(new TextWatcher() {

        @Override
        public void onTextChanged(CharSequence s, int start, int before,
                int count) {
            // TODO Auto-generated method stub
            if (s.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

        }
    });

###

If you want to use an object oriented solution and reuse your code

public abstract class EmptyTextWatcher implements TextWatcher
{
    public abstract void onEmptyField();

    public abstract void onFilledField();

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count)
    {
        if (s.toString().trim().length() == 0)
        {
            onEmptyField();
        } else
        {
            onFilledField();
        }
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after)
    {

    }



    @Override
    public void afterTextChanged(Editable s)
    {

    }

}

so you can use it just doing

textView.addTextChangedListener(new EmptyTextWatcher()
        {

            @Override
            public void onEmptyField()
            {
                button.setEnabled(false);
            }

            @Override
            public void onFilledField()
            {
                button.setEnabled(true);
            }
        });

###

if anyone was wondering here is the kotlin version of the code

editText1.addTextChangedListener(object: TextWatcher {
        override fun onTextChanged(s:CharSequence, start:Int, before:Int, count:Int) {
            if (s.toString().trim({ it <= ' ' }).isEmpty())
            {
                button.setEnabled(false)
            }
            else
            {
                button.setEnabled(true)
            }
        }
        override fun beforeTextChanged(s:CharSequence, start:Int, count:Int,
                              after:Int) {
            // TODO Auto-generated method stub
        }
        override fun afterTextChanged(s: Editable) {
            // TODO Auto-generated method stub
        }
    })

Leave a Reply

Your email address will not be published. Required fields are marked *