I'm new to Android programming.
My following program does a simple Farenheit to Celsius conversion. If you enter values in a Farenheit EditText
it will convert it into Celsius for every keystroke entered.
I'm getting the following errors, the Changes I make in Celsius edit text are not reflected in Fahrenheit.
07-29 01:59:21.189: E/AndroidRuntime(1390): java.lang.NumberFormatException: Invalid float: ""
Following is my MainActivity.java
:
public class MainActivity extends Activity {
private EditText celsiusText;
private EditText farenheitText;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
celsiusText = (EditText) findViewById(R.id.editText1);
farenheitText = (EditText) findViewById(R.id.editText2);
celsiusText.requestFocus();
celsiusText.setOnFocusChangeListener((OnFocusChangeListener) this);
farenheitText.setOnFocusChangeListener((OnFocusChangeListener) this);
}
public void onFocusChange(View v, boolean hasFocus) {
TextWatcher watcher1 = new TextWatcher() {
public void afterTextChanged(Editable s) {
}
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
// empty
}
public void onTextChanged(CharSequence S,int start,int before, int count) {
float inputValue;
if (!S.toString().equals("")) {
inputValue = Float.parseFloat(S.toString());
(findViewById(R.id.editText1)).setText(String
.valueOf(convertFahrenheitToCelsius(inputValue)));
} else {
(findViewById(R.id.editText1)).setText("");
return;
}
}
};
TextWatcher watcher2 = new TextWatcher() {
public void afterTextChanged(Editable s) {
// empty
}
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
// empty
}
public void onTextChanged(CharSequence S,int start,int before, int count) {
float inputValue;
if (!S.toString().equals("")) {
inputValue = Float.parseFloat(S.toString());
(findViewById(R.id.editText2)).setText(String
.valueOf(convertCelsiusToFahrenheit(inputValue)));
} else {
(findViewById(R.id.editText2)).setText("");
return;
}
}
};
if((v == findViewById(R.id.editText2)) && hasFocus) {
farenheitText.addTextChangedListener(watcher1);
} else if ((v == findViewById(R.id.editText1)) && hasFocus) {
(findViewById(R.id.editText1)).setText("");
celsiusText.addTextChangedListener(watcher2);
}
}
//Converts to celsius
private float convertFahrenheitToCelsius(float fahrenheit) {
return ((fahrenheit - 32) * 5 / 9);
}
// Converts to fahrenheit
private float convertCelsiusToFahrenheit(float celsius) {
return ((celsius * 9) / 5) + 32;
}
}
My activity_main.xml
:
<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"
android:paddingLeft="16dp"
android:paddingRight="16dp" >
<EditText
android:id="@+id/editText1"
android:layout_width="128dp"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginTop="62dp"
android:ems="10"
android:inputType="numberSigned" >
<requestFocus />
</EditText>
<EditText
android:id="@+id/editText2"
android:layout_width="128dp"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/editText1"
android:layout_alignBottom="@+id/editText1"
android:layout_alignParentRight="true"
android:ems="10"
android:inputType="numberSigned" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/editText1"
android:layout_below="@+id/editText1"
android:layout_marginTop="18dp"
android:text="@string/celsius"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/textView1"
android:layout_alignBottom="@+id/textView1"
android:layout_alignRight="@+id/editText2"
android:text="@string/fahrenheit"
android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>
some times clearfocus()
solves this problem. try to call editText1.clearfocus()
in onCreate()
method or other suitable places of code.