Android Programming Tips

INDEX
Converting a string to an integer on Android
Converting a int to an string on Android
Converting a string to an double on Android
Converting a long to an string on Android
Decimal Format
Android Date Format Change
Set the focus on EditText Programmatically
Check If EditText is empty
Preventing going back to the previous activity
Set max-length of EditText programmatically with other InputFilter
String comparison - Android

Converting a string to an integer on Android

int in = Integer.valueOf(et.getText().toString());
//or
int in2 = new Integer(et.getText().toString());

Converting a int to an string o android

int tmpInt = 10;
String tmpStr10 = String.valueOf(tmpInt);

int tmpInt = 10;
String tmpStr10 = Integer.toString(tmpInt);

Converting a string to an double on Android

try this:

double d= Double.parseDouble(yourString);

Converting a long to an string on Android

String strLong = Long.toString(longNumber);

Decimal Format

new DecimalFormat("##,##,##0").format(amount);

Displaying Currency in Indian Numbering Format

Examples:

amount.setText(new DecimalFormat("####0.00").format(amount_item).toString());

or

total.setText(new DecimalFormat("####0.00").format(Double.parseDouble(txtCount.getText().toString()) * amount_item));

Android Date Format Change

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String date = sdf.format(new Date());

The date format in sqlite should be of following format:

YYYY-MM-DD
YYYY-MM-DD HH:MM
YYYY-MM-DD HH:MM:SS
YYYY-MM-DD HH:MM:SS.SSS
YYYY-MM-DDTHH:MM
YYYY-MM-DDTHH:MM:SS
YYYY-MM-DDTHH:MM:SS.SSS
HH:MM
HH:MM:SS
HH:MM:SS.SSS
now
DDDDDDDDDD 

For more details, have a look: http://www.sqlite.org/lang_datefunc.html

set the focus on EditText Programmatically

editText = (EditText)findViewById(R.id.myTextViewId); 

editText.requestFocus();

Check If EditText is empty

if(txtNumber.getText().toString().trim().length() == 0){
    Toast.makeText(getApplicationContext(),"Number cannot be blank!" ,Toast.LENGTH_SHORT).show();
    txtNumber.requestFocus();
    return;
}

use the TextUtils class like this :

if(TextUtils.isEmpty(strUserName)) {
    Toast.makeText(this, "plz enter your name ", Toast.LENGTH_SHORT).show();
    return;
}

This example check If EditText is empty and value must be a graterthan zero

if(txtCount.getText().toString().trim().length() == 0 || Integer.parseInt(txtCount.getText().toString()) <1){
    Toast.makeText(getApplicationContext(),"Count cannot be blank!" ,Toast.LENGTH_SHORT).show();
    txtCount.setText("");
    txtCount.requestFocus();
    return;
}

Preventing going back to the previous activity

Following solution can be pretty useful in the usual login / main activity scenario or implementing a blocking screen.

To minimize the app rather than going back to previous activity, you can override onBackPressed() like this:

@Override
public void onBackPressed() {
    moveTaskToBack(true);
}

Another Solutions

LoginActivity on successful login starts the Main activity and this time because the user is logged on, the Main activity will continue its normal course. LoginActivity is declared as following in the manifest file:

<activity android:name="LoginScreen" android:label="@string/app_name"
    android:noHistory="true" android:excludeFromRecents="true">
</activity>

Setting noHistory and excludeFromRecents to true for LoginActivity means that the user cant return to this activity using back button.

Set max-length of EditText programmatically with other InputFilter



Use InputFilter set text length

Limit the character input in an EditText , EditText in XML layout gives us android:maxLength 

Try this

txtNumber.setFilters(new InputFilter[]{new InputFilter.LengthFilter(3)});




function

public void setEditTextMaxLength(int length) {
    InputFilter[] FilterArray = new InputFilter[1];
    FilterArray[0] = new InputFilter.LengthFilter(length);
    edt_text.setFilters(FilterArray);
}

EditText et = new EditText(this);
int maxLength = 3;
InputFilter[] FilterArray = new InputFilter[1];
FilterArray[0] = new InputFilter.LengthFilter(maxLength);
et.setFilters(FilterArray);

public void setEditTextMaxLength(final EditText editText, int length) {
    InputFilter[] FilterArray = new InputFilter[1];
    FilterArray[0] = new InputFilter.LengthFilter(length);
    editText.setFilters(FilterArray);
}

String comparison - Android

Check equals

if(item=="ALL"){

    ..........

    ..........
}

Android string comparison for use equal() method to compare the value of the objects.

if(gender.equals("Male"))
 salutation ="Mr.";
if(gender.equals("Female"))
 salutation ="Ms.";

string1.equals(string2)
// returns true if both strings are equal

string1.compareTo(string2)
// returns 0 if both strings are equal