Develop Reference

How to set if else condition on button being clicked or not in android?

I would like to know how to set an if else condition where the next button have to be disabled if none of the buttons are being clicked. Otherwise, they are able to proceed to next question?
private AdvancedQuestion nAdvancedQuestion = new AdvancedQuestion();
private TextView nScoresView;
private TextView nQuestionsView;
private TextView tvTime;
private Button nButtonChoices1;
private Button nButtonChoices2;
private Button nButtonChoices3;
private Button nButtonChoices4;
private String nAnswers;
private int nScores = 0;
private int nQuestionNumbers = 0;
Button btnNextz;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_advanced_quiz);
updateQuestions();
nButtonChoices1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (nButtonChoices1.getText() == nAnswers) {
correctSound.start();
nScores = nScores + 1;
nButtonChoices1.setEnabled(false);
nButtonChoices2.setEnabled(false);
nButtonChoices3.setEnabled(false);
nButtonChoices4.setEnabled(false);
nButtonChoices1.getBackground().setColorFilter(Color.GREEN, PorterDuff.Mode.MULTIPLY);
Toast.makeText(advancedQuiz.this, "correct", Toast.LENGTH_SHORT).show();
} else {
wrongSound.start();
Toast.makeText(advancedQuiz.this, "wrong", Toast.LENGTH_SHORT).show();
nButtonChoices1.setEnabled(false);
nButtonChoices2.setEnabled(false);
nButtonChoices3.setEnabled(false);
nButtonChoices4.setEnabled(false);
}
}
});
btnNextz.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
nextSound.start();
updateQuestions();
nButtonChoices1.setEnabled(true);
nButtonChoices2.setEnabled(true);
nButtonChoices3.setEnabled(true);
nButtonChoices4.setEnabled(true);
nButtonChoices1.getBackground().setColorFilter(Color.WHITE, PorterDuff.Mode.MULTIPLY);
nButtonChoices2.getBackground().setColorFilter(Color.WHITE, PorterDuff.Mode.MULTIPLY);
nButtonChoices3.getBackground().setColorFilter(Color.WHITE, PorterDuff.Mode.MULTIPLY);
nButtonChoices4.getBackground().setColorFilter(Color.WHITE, PorterDuff.Mode.MULTIPLY);
}
private void updateQuestions() {
nQuestionsView.setText(nAdvancedQuestion.getQuestions(nQuestionNumbers));
nButtonChoices1.setText(nAdvancedQuestion.getChoices1(nQuestionNumbers));
nButtonChoices2.setText(nAdvancedQuestion.getChoices2(nQuestionNumbers));
nButtonChoices3.setText(nAdvancedQuestion.getChoices3(nQuestionNumbers));
nButtonChoices4.setText(nAdvancedQuestion.getChoices4(nQuestionNumbers));
nAnswers = nAdvancedQuestion.getCorrectAnswers(nQuestionNumbers);
nQuestionNumbers++;
}
private void updateScore(int points) {
nScoresView.setText("" + nScores);
}
Please note there is 4 possible answers. If none of them are selected, they cannot proceed to the next question until one button is press so they can go to the next question. The updateQuestions() is the part where i believe it will show next question.

This is a simple example on how to disable/enable a button based on an if condition -
int count = 0;
if (count == 0) {
NextButton.setEnabled(false);
}
#Override
public void onClick(View v) {
switch(v.getId()) {
case R.id.otherButtons:
count++;
NextButton.setEnabled(true);
Toast.makeText(this, "Button Disabled", Toast.LENGTH_LONG).show();
break;
case R.id.nextButton:
//Move the user to the next question
break;
}
}
Also check out this link

You will need to add a button element in the view of the activity you want it to appear on, then add an event listener to it either in the activity code or specify which function to call on click in the activities XML layout file.
See: https://developer.android.com/reference/android/widget/Button.html

Android Calculator Backspace button

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.

how do I set up a next and previous button

Hello as the title state I'm trying to setup a next and previous buttons but I'm still new at coding so this has me a little confused.
I tried to use if statements with an enum within a single button but it defaults to last if statement when the event is handled here's the code-
private enum EVENT{
pe1, pe2, pe3, pe4;
}
EVENT currentEvent = EVENT.pe1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_one_liners);
nextBtn = (Button) findViewById(R.id.nextBtn);
olText = (TextView) findViewById(R.id.olText);
nextBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (currentEvent==EVENT.pe1) {
olText.setText("PE1");
olText.startAnimation(AnimationUtils.loadAnimation(olText.this, android.R.anim.slide_in_left));
currentEvent=EVENT.pe2;
}
if (currentEvent==EVENT.pe2){
olText.setText("PE2");
olText.startAnimation(AnimationUtils.loadAnimation(olText.this, android.R.anim.slide_in_left));
currentEvent=EVENT.pe3;
}
}
});
}
I tried to use the enumerator to assign a number to each if statement so when the user hit previous it would subtract and when they hit next it would add, each number would have some text or image within its if statement but as I said it defaults to the last if statement- Any help is much appreciated.

How about this?
int eventNum = 0;
int maxEvents = XXX;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_one_liners);
prevBtn = (Button) findViewById(R.id.prevBtn);
nextBtn = (Button) findViewById(R.id.nextBtn);
olText = (TextView) findViewById(R.id.olText);
setEventData(true);
View.OnClickListener listener = new View.OnClickListener() {
#Override
public void onClick(View v) {
if(v.equals(prevBtn) && eventNum > 0) {
eventNum--;
setEventData(false);
return;
}
if(v.equals(nextBtn) && eventNum < maxEvents - 1) {
eventNum++;
setEventData(true);
return;
}
}
}
nextBtn.setOnClickListener(listener);
prevBtn.setOnClickListener(listener);
}
private void setEventData(boolean animLeft) {
olText.setText("PE" + (eventNum + 1));
if(animLeft) {
olText.startAnimation(AnimationUtils.loadAnimation(olText.this, android.R.anim.slide_in_left));
} else {
olText.startAnimation(AnimationUtils.loadAnimation(olText.this, android.R.anim.slide_in_right));
}
}

You'll want to create a class variable that keeps track of which text your TextView is showing. So in the following example, I create a list of Strings that I just store in a String array. Then I create an iterator variable which stores which String from the list I'm currently viewing in the TextView. Every time you click the previous or next button, you simply store your current state in the iterator variable so you can recall it the next time a click event comes in.
String[] labels = {"one", "two", "three", "four"};
int currentView = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void onPreviousButtonClicked(View view) {
TextView textView = (TextView) findViewById(R.id.clickableLink);
currentView--; //decrement our iterator
if(currentView < 0) currentView = 0; //check to make sure we didn't go below zero
textView.setText(labels[currentView]);
}
public void onNextButtonClicked(View view) {
TextView textView = (TextView) findViewById(R.id.clickableLink);
currentView++; //increment our iterator
if(currentView > labels.length-1) currentView = labels.length-1; //check to make sure we didn't go outside the array
textView.setText(labels[currentView]);
}

Compare data from edit text with data from if statement

I'm making a quiz app. User has to finish the phrase shown on display and write the name of the car in the edittext, after pushing on button, if the answer right, edittext become green, if doesn't, become red. If all answers right (green), intent move on next activity.
I have some difficulties with if statement edit text become red even the answer was right. Also how to make INTENT to move on next activity if all right, if not it doesn't move?
public class MainActivity extends AppCompatActivity {
EditText et_one_one, et_one_two, et_one_three;
Button buttonCheck;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_one_one = (EditText) findViewById(R.id.et_one_one);
et_one_two = (EditText) findViewById(R.id.et_one_two);
et_one_three = (EditText) findViewById(R.id.et_one_three);
final String t1 = et_one_one.getText().toString();
final String t2 = et_one_two.getText().toString();
final String t3 = et_one_three.getText().toString();
buttonCheck = (Button) findViewById(R.id.buttonCheck);
buttonCheck.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (t1.equals("maserati")){
et_one_one.setBackgroundColor(Color.GREEN);
}
else {
et_one_one.setBackgroundColor(Color.RED);
}
if (t2.equals("mercedes")){
et_one_two.setBackgroundColor(Color.GREEN);
}
else{
et_one_two.setBackgroundColor(Color.RED);
}
if (t3.equals("bmw")){
et_one_three.setBackgroundColor(Color.GREEN);
}
else{
et_one_three.setBackgroundColor(Color.RED);
}
}
});
}
}

You're changing the color of just the et_one_one each time in your if else statements. Shouldn't it be for different edittexts?
buttonCheck.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
boolean allAnswersCorrect = true;
String t1 = et_one_one.getText().toString();
String t2 = et_one_two.getText().toString();
String t3 = et_one_three.getText().toString();
if (t1.equals("maserati")){
et_one_one.setBackgroundColor(Color.GREEN);
}
else {
allAnswersCorrect = false;
et_one_one.setBackgroundColor(Color.RED);
}
if (t2.equals("mercedes")){
et_one_two.setBackgroundColor(Color.GREEN);
}
else{
allAnswersCorrect = false;
et_one_two.setBackgroundColor(Color.RED);
}
if (t3.equals("bmw")){
et_one_three.setBackgroundColor(Color.GREEN);
}
else{
allAnswersCorrect = false;
et_one_three.setBackgroundColor(Color.RED);
}
if(allAnswersCorrect){
Intent intent = new Intent(YourActivity.this, YourSecondActivity.class);
startActivity(intent);
}
}
});
Maintain a allAnswersCorrect boolean to check whether your answers are correct or not. If all are correct the move to your next activity.

You should use t2.equals("maserati"), and it will be ok.

Perform action only if two buttons are clicked

This is the first time I'm ever dabbling in Android development so please bear with me.
My requirement is this:
I have two buttons on screen, A and B. If the user presses both buttons (order doesn't matter), I need another page to be displayed. Pressing either A or B should do nothing.
Is this possible? If so, how would I achieve this?
Thank you.

This is possible if you take a flag. (boolean)
You should set a flag in your button listeners.
public class Mtest extends Activity {
Button b1;
Button b2;
boolean flag_1 = false;
boolean flag_2 = false;
public void onCreate(Bundle savedInstanceState) {
...
b1 = (Button) findViewById(R.id.b1);
b2 = (Button) findViewById(R.id.b2);
b1.setOnClickListener(myhandler1);
b2.setOnClickListener(myhandler2);
}
View.OnClickListener myhandler1 = new View.OnClickListener() {
public void onClick(View v) {
// it was the 1st button
flag_1 = true;
doSomething();
}
};
View.OnClickListener myhandler2 = new View.OnClickListener() {
public void onClick(View v) {
// it was the 2nd button
flag_2 = true;
doSomething();
}
};
}
public void doSomething(){
if(flag_1 && flag_2)
{
//DO SOMETHING
}
}
}

Create two boolean's like button1isClickedand button2isClicked,then set an onClickListener for each Button. When the the Button is clicked set the value of these two boolean's to true, then simply create an if() statement that will chekc to see if both buttons have been clicked, like this:
if(button1isClicked == true && button2isClicked == true){
//display your new page
}