Any idea how to illustrate backspace funtion in this code? I try to make some changes but it can't work the backspace function. So, i would like to help me, with the backspace button.
enter code here
public class MainActivity extends AppCompatActivity implements OnClickListener {
private TextView mCalculatorDisplay;
private Boolean userIsInTheMiddleOfTypingANumber = false;
private CalculatorBrain mCalculatorBrain;
private static final String DIGITS = "0123456789.";
DecimalFormat df = new DecimalFormat("############");
#SuppressLint("NewApi")
#Override
protected void onCreate(Bundle savedInstanceState) {
// hide the window title.
requestWindowFeature(Window.FEATURE_NO_TITLE);
// hide the status bar and other OS-level chrome
getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mCalculatorBrain = new CalculatorBrain();
mCalculatorDisplay = (TextView) findViewById(R.id.textView1);
df.setMinimumFractionDigits(0);
df.setMinimumIntegerDigits(1);
df.setMaximumIntegerDigits(8);
findViewById(R.id.button0).setOnClickListener(this);
findViewById(R.id.button1).setOnClickListener(this);
findViewById(R.id.button2).setOnClickListener(this);
findViewById(R.id.button3).setOnClickListener(this);
findViewById(R.id.button4).setOnClickListener(this);
findViewById(R.id.button5).setOnClickListener(this);
findViewById(R.id.button6).setOnClickListener(this);
findViewById(R.id.button7).setOnClickListener(this);
findViewById(R.id.button8).setOnClickListener(this);
findViewById(R.id.button9).setOnClickListener(this);
findViewById(R.id.buttonBackspace).setOnClickListener(this);
findViewById(R.id.buttonAdd).setOnClickListener(this);
findViewById(R.id.buttonSubtract).setOnClickListener(this);
findViewById(R.id.buttonMultiply).setOnClickListener(this);
findViewById(R.id.buttonDivide).setOnClickListener(this);
findViewById(R.id.buttonToggleSign).setOnClickListener(this);
findViewById(R.id.buttonDecimalPoint).setOnClickListener(this);
findViewById(R.id.buttonEquals).setOnClickListener(this);
findViewById(R.id.buttonClear).setOnClickListener(this);
// The following buttons only exist in layout-land (Landscape mode) and require extra attention.
// The messier option is to place the buttons in the regular layout too and set android:visibility="invisible".
if (findViewById(R.id.buttonSquareRoot) != null) {
findViewById(R.id.buttonSquareRoot).setOnClickListener(this);
}
if (findViewById(R.id.buttonSquared) != null) {
findViewById(R.id.buttonSquared).setOnClickListener(this);
}
if (findViewById(R.id.buttonInvert) != null) {
findViewById(R.id.buttonInvert).setOnClickListener(this);
}
if (findViewById(R.id.buttonSine) != null) {
findViewById(R.id.buttonSine).setOnClickListener(this);
}
if (findViewById(R.id.buttonCosine) != null) {
findViewById(R.id.buttonCosine).setOnClickListener(this);
}
if (findViewById(R.id.buttonTangent) != null) {
findViewById(R.id.buttonTangent).setOnClickListener(this);
}
}
#Override
public void onClick (View v) {
String buttonPressed = ((Button) v).getText().toString();
if (DIGITS.contains(buttonPressed)) {
// digit was pressed
if (userIsInTheMiddleOfTypingANumber) {
if (buttonPressed.equals(".") && mCalculatorDisplay.getText().toString().contains(".")) {
// ERROR PREVENTION
// Eliminate entering multiple decimals
} else {
mCalculatorDisplay.append(buttonPressed);
}
} else {
if (buttonPressed.equals(".")) {
// ERROR PREVENTION
// This will avoid error if only the decimal is hit before an operator, by placing a leading zero
// before the decimal
mCalculatorDisplay.setText(0 + buttonPressed);
} else {
mCalculatorDisplay.setText(buttonPressed);
}
}
userIsInTheMiddleOfTypingANumber = true;
}else{
// operation was pressed
if (userIsInTheMiddleOfTypingANumber) {
mCalculatorBrain.setOperand(Double.parseDouble(mCalculatorDisplay.getText().toString()));
userIsInTheMiddleOfTypingANumber = false;
}
mCalculatorBrain.performOperation(buttonPressed);
if (new Double(mCalculatorBrain.getResult()).equals(0.0)) {
mCalculatorDisplay.setText("" + 0);
} else {
mCalculatorDisplay.setText(df.format(mCalculatorBrain.getResult()));
}
}
}
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
// Save variables on screen orientation change
outState.putDouble("OPERAND", mCalculatorBrain.getResult());
outState.putDouble("MEMORY", mCalculatorBrain.getMemory());
}
#Override
protected void onRestoreInstanceState(Bundle savedInstanceState){
super.onRestoreInstanceState(savedInstanceState);
// Restore variables on screen orientation change
mCalculatorBrain.setOperand(savedInstanceState.getDouble("OPERAND"));
mCalculatorBrain.setMemory(savedInstanceState.getDouble("MEMORY"));
if (new Double(mCalculatorBrain.getResult()).equals(0.0)){
mCalculatorDisplay.setText("" + 0);
} else {
mCalculatorDisplay.setText(df.format(mCalculatorBrain.getResult()));
}
}
}
In your layout you can add a onClick attribute to each button, say onClick="function", and in your activity you just need to implement a method like this:
public void function(View v) {
switch(v.getId()) {
case R.id.buttonBackspace:
// handle the backspace button
break;
case R.id.xxx:
// handle the button
break;
...
}
}
And for digits, I suggest assign a tag to each digit button in the layout, and do your logic in java based on the tag, instead of the text on the button. Because the text is just a UI, it might change in the future due to other possible requirements.
I have two date fields (no, not the pickers) as fromDate and toDate. When I click on my Submit button, in the onResume(), I have validations in place for both date fields. When I enter an invalid value (not from syntax, locale, etc. point of view) for toDate and click Submit, I correctly see the toast. Then, I enter the correct the value and click Submit. The toast still appears ! In other words, the corrected date value is not being received.
I guess, I am missing the activity life-cycle w.r.t. toasts. (Each Toast is immediately followed by a return.) Can you please suggest what should be the correct flow to handle this error followed by correction ?
public class MainActivity extends Activity {
private Locale l ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Set locale;
l = getResources().getConfiguration().locale;
}
#Override
protected void onResume() {
super.onResume();
addButtonListener();
}
private void addButtonListener() {
Button submitButton = (Button) findViewById(R.id.buttonSubmit);
submitButton.setOnClickListener(new OnClickListener() {
EditText fromDateText = (EditText) findViewById(R.id.fromDate);
EditText toDateText = (EditText) findViewById(R.id.toDate);
#Override
public void onClick(View v) {
String s;
if (fromDateText.getText().toString().isEmpty()) {
Toast.makeText(getApplicationContext(), R.string.err_fromDate_1, Toast.LENGTH_SHORT).show();
return;
}
if (toDateText.getText().toString().isEmpty()) {
Toast.makeText(getApplicationContext(), R.string.err_toDate_1, Toast.LENGTH_SHORT).show();
return;
}
}
});
}
}
Edited to add source code.
Make fromDateText and toDateText class variables and init them in onCreate.
Can any one tell me? how can i use the same button for two Action?
Like em using one button in my activity that calculate some values and after calculating the when i again press same button then reset the all fields. Like in this Application
http://www.craziness.com/games/play-love-tester/ when i test the love by pressing the button
then i again press the same button then all fields reset.
what should i use in my activity for the above problem?
You can create a global variable which indicates the state of the program and then change this value when needed. In the OnClickListener of your Button you create an if statement which checks this variable and does the needed things for the associated value.
Example:
public class MainActivity extends Activity {
private int state = 0;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (state == 0) {
// State 1
}
else if (state == 1) {
// State 2
}
else {
// Default state
}
}
});
// Rest of your code including state changing part
}
}
You can do it by changing the button text.
If you do not want that someone sees the text change. Test (example "click" and the other state "click " (1 blank at the end) or another solution.
....
Button bt = (Button) findViewById(R.id.button);
bt.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// todo: check for expected instance (Button)
Button btc = (Button)v;
String bText = btc.getText().toString();
if (bText == "open") {
btc.setText("close");
}
else if (bText == "close") {
btc.setText("open");
}
}
[...]
You can do so by using a toggle button.
In your xml file add a toggle button
<ToggleButton
android:id="#+id/tbtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""
android:textOff="Reset"
android:textOn="Calculation"
android:background="#drawable/icon"/>
Java file
public class Reviews extends Activity implements OnClickListener {
private ToggleButton tbtn;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
tbtn = (ToggleButton) findViewById(R.id.tbtn);
tbtn.setOnClickListener(this);
public void onClick(View view) {
if (tbtn.isChecked()) {
//calculate the result
}
else {
//Reset your global calculation variable;
}
}
}
}
I'm trying to create a simple username/password login screen. I have the layout done, and right now, I'm trying to set it so when the username (EditText) == "crete", then it should do something. Here is my code...:
public class Login extends Activity {
public static EditText username, password;
public Button loginbutton;
boolean accessgranted;
public String dbu, dbp, user1;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
username = (EditText) this.findViewById(R.id.username);
password = (EditText) this.findViewById(R.id.password);
loginbutton = (Button) this.findViewById(R.id.loginbutton);
user1 = "crete";
loginbutton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try{
dbu = (username.getText()).toString();
}
finally{
if (dbu == user1){
username.setText("SUCCESS");
}
}
}
});
}
}
this, sadly, doesn't work. It correctly converts it to a string (i think) because when I tested this code out :
loginbutton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try{
dbu = (username.getText()).toString();
}
finally{
username.setText("done" + dbu);
}
}
}
});
It correctly enters what you entered into the EditText, plus the word "done".
There seems to be a problem with creating if-then statements??
You test for String equality with the method .equals("String").
With == you are testing if the references to the objects are equal.
Try using equalsIgnoreCase(String) instead of the == comparator.
Like this: dbu.equalsIgnoreCase(user1)
dub and user1 are two separate String objects. You're comparing them like this: dbu == user1. This will always return false. Instead, replace it with dbu.equals(user1).
This question already has answers here:
Why does my Android app crash with a NullPointerException when initializing a variable with findViewById(R.id.******) at the beginning of the class?
(9 answers)
Android setOnClickListener method - How does it work?
(5 answers)
Closed 1 year ago.
I'm trying to set and onclicklistener so that when I click within the edittext element it will clear its current contents. Is there something wrong here? When I compile this code I get a force quit and ActivityManager: Can't dispatch DDM chunk 4d505251: no handler defined error.
public class Project extends Activity implements OnClickListener {
/** Called when the activity is first created. */
EditText editText = (EditText)findViewById(R.id.editText1);
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
editText.setOnClickListener(this);
setContentView(R.layout.main);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
editText.setText("");
}
}
Also you can use code below
editText.getText().clear();
First you need to call setContentView(R.layout.main) then all other initialization.
Please try below Code.
public class Trackfolio extends Activity implements OnClickListener {
/** Called when the activity is first created. */
public EditText editText;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
editText = (EditText) findViewById(R.id.editText1);
editText.setOnClickListener(this);
}
#Override
public void onClick(View v) {
editText.getText().clear(); //or you can use editText.setText("");
}
}
just use the android:hint attribute in your EditText. This text shows up when the box is empty and not focused, but disappears upon selecting the EditText box.
We can clear EditText data in two ways
First One setting EditText is empty like below line
editext.setText("");
Second one clearing EditText data like this
editText.getText().clear();
I suggest second way
Your code should be:
public class Project extends Activity implements OnClickListener {
/** Called when the activity is first created. */
EditText editText;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
editText = (EditText)findViewById(R.id.editText1);
editText.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(v == editText) {
editText.setText("");
}
}
}
For Kotlin:
Create two extensions, one for EditText and one for TextView
EditText:
fun EditText.clear() { text.clear() }
TextView:
fun TextView.clear() { text = "" }
and use it like
myEditText.clear()
myTextView.clear()
public EditText editField;
public Button clear = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.text_layout);
this. editField = (EditText)findViewById(R.id.userName);
this.clear = (Button) findViewById(R.id.clear_button);
this.editField.setOnClickListener(this);
this.clear.setOnClickListener(this);
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(v.getId()==R.id.clear_button){
//setText will remove all text that is written by someone
editField.setText("");
}
}
Very Simple to clear editText values.when u click button then only follow 1 line code.
Inside button or anywhere u want.Only use this
editText.setText("");
package com.example.sampleproject;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
public class SampleProject extends Activity {
EditText mSearchpeople;
Button mCancel , msearchclose;
ImageView mprofile, mContact, mcalender, mConnection, mGroup , mFollowup , msetting , mAddacard;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.dashboard);
mSearchpeople = (EditText)findViewById(R.id.editText1);
mCancel = (Button)findViewById(R.id.button2);
msearchclose = (Button)findViewById(R.id.button1);
mprofile = (ImageView)findViewById(R.id.imageView1);
mContact = (ImageView)findViewById(R.id.imageView2);
mcalender = (ImageView)findViewById(R.id.imageView3);
mConnection = (ImageView)findViewById(R.id.imageView4);
mGroup = (ImageView)findViewById(R.id.imageView5);
mFollowup = (ImageView)findViewById(R.id.imageView6);
msetting = (ImageView)findViewById(R.id.imageView7);
mAddacard = (ImageView)findViewById(R.id.imageView8);
}
#Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
mCancel.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
mSearchpeople.clearFocus();
}
});
}
}
i don't know what mistakes i did while implementing the above solutions, bt they were unsuccessful for me
txtDeck.setOnFocusChangeListener(new OnFocusChangeListener() {
#Override
public void onFocusChange(View v, boolean hasFocus) {
txtDeck.setText("");
}
});
This works for me,
//To clear When Clear Button is Clicked
firstName = (EditText) findViewById(R.id.firstName);
clear = (Button) findViewById(R.id.clearsearchSubmit);
clear.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (v.getId() == R.id.clearsearchSubmit);
firstName.setText("");
}
});
This will help to clear the wrong keywords that you have typed in so instead of pressing backspace again and again you can simply click the button to clear everything.It Worked For me. Hope It Helps
final EditText childItem = (EditText) convertView.findViewById(R.id.child_item);
childItem.setHint(cellData);
childItem.setOnFocusChangeListener(new View.OnFocusChangeListener() {
#Override
public void onFocusChange(View v, boolean hasFocus) {
//Log.d("NNN", "Has focus " + hasFocus);
if (hasFocus) {
Toast.makeText(ctx.getApplicationContext(), "got the focus", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(ctx.getApplicationContext(),
"loss the focus", Toast.LENGTH_SHORT).show();
}
return;
});
by setting Empty string you can clear your edittext
editext.setText("");
If the use of EditText is not mandatory, you can implement this behavior easily with the new material components:
<com.google.android.material.textfield.TextInputLayout
style="#style/Widget.MaterialComponents.TextInputLayout.OutlinedBox.Dense"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/hint_field"
app:endIconDrawable="#drawable/ic_close_black_24dp"
app:endIconMode="clear_text"
app:endIconTint="#color/black">
<com.google.android.material.textfield.TextInputEditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/hint_value"
android:maxLines="1"
android:text="#{itemModel.value}" />
</com.google.android.material.textfield.TextInputLayout>
You only have to specify the drawable you want for the button that will clear the text and the action that it will execute. To clear the text, you can use iconMode="clear_text", but also "password_toggle" is available.
In XML you can write like:
<EditText
android:id="#+id/txtsearch"
android:layout_width="250dp"
android:layout_height="match_parent"
android:layout_gravity="right"
android:layout_weight="1"
android:background="#drawable/roundlayoutbutton1"
android:ems="10"
android:gravity="center"
android:inputType="text"
android:textAllCaps="true"
android:text="search_xxxx"
android:textColor="#color/colorPrimaryDark"
android:visibility="visible" />
and in java class you may have below one :
EditText searchHost;
OnCreate() you write:
searchHost=findViewById(R.id.txtsearch);
searchHost.setOnFocusChangeListener(new View.OnFocusChangeListener() {
#Override
public void onFocusChange(View v, boolean hasFocus) {
if(searchHost.getText().toString().equalsIgnoreCase("search_xxxx")){
searchHost.setText("");
Toast.makeText(getApplicationContext(),"Enter you text xxx...", Toast.LENGTH_LONG).show();
}
}
});
It works fine for me.
You can use the 'android:hint' attribute in your EditText also from code:
editText.setHint(CharSequence hint / int resid);
Then you don't need any onClickListener or similar. But consider that the hint value won't be passed. The editText will be stayed empty. In this case you can set your editText with your deflault value:
if(editText.getText().toString().equals("")) {
...use your default value instead of the editText... }
It's simple: declare the widget variables (editText, textView, button etc.) in class but initialize it in onCreate after setContentView.
The problem is when you try to access a widget of a layout first you have to declare the layout. Declaring the layout is setContentView.
And when you initialize the widget variable via findViewById you are accessing the id of the widget in the main layout in the setContentView.
I hope you get it!
I am not sure if your searching for this one
{
<EditText
.
.
android:hint="Please enter your name here">
}