I hope this isn't a stupid question. I'm having some trouble clearing a TextView. I've looked around and everyone keeps saying use: textView.setText(""); in onCreate but doesn't seem to work for some reason. Basically, my app just accepts a number from an editText then runs the Fibonacci sequence (when a button is clicked) and displays the result in a textView. Well, the sequence displays fine but I want the textview to clear every time I click the button - so far it just keeps adding more text to what's already there.
Am I placing textView.setText(""); in the wrong location? Or am I just missing some other concept? (I also tried placing it from my OnClick - that didn't work either).
Here is my code:
public class MainActivity extends Activity {
// primary widgets
private EditText editText;
private TextView textView;
private Button button1;
static ArrayList<Integer> fibList = new ArrayList<Integer>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = (EditText) findViewById(R.id.editText1);
textView = (TextView) findViewById(R.id.textView2);
button1 = (Button) findViewById(R.id.button1);
//Attempt to clear TextView
textView.setText("");
button1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
String input = editText.getText().toString();
int number = Integer.parseInt(input);
int tmp = 0;
// confirm input
if (number < 20) {
Toast.makeText(getApplicationContext(),
"You entered: " + number, Toast.LENGTH_LONG).show();
for (int i = 0; i <= number; i++) {
fibList.add(fib(i));
// sum even numbers
if (fib(i) % 2 == 0) {
tmp += fib(i);
}
}
} else {
Toast.makeText(getApplicationContext(),
"Number is too Large: " + number, Toast.LENGTH_LONG)
.show();
}
String array = fibList.toString();
textView.setText(array);
}
});
}
// run fibonacci sequence
public static int fib(int n) {
if (n < 2) {
return n;
} else {
return fib(n - 1) + fib(n - 2);
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
If you want the TextView to clear on each button click then the .setText must go in you onClick. The reason you would put the .setText in your onCreate is to clear the text as soon as your activity is created, but you do not have anything to clear just yet since your button has not yet been pushed so setText will do nothing. Also, since your onCreate will only run once for your activity, it will never go back to the setText again. Try the following:
public class MainActivity extends Activity {
// primary widgets
private EditText editText;
private TextView textView;
private Button button1;
static ArrayList<Integer> fibList = new ArrayList<Integer>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = (EditText) findViewById(R.id.editText1);
textView = (TextView) findViewById(R.id.textView2);
button1 = (Button) findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
textView.setText(""); //Clear the TextView
fibList.clear(); //Clear your array list before adding new elements
String input = editText.getText().toString();
int number = Integer.parseInt(input);
int tmp = 0;
// confirm input
if (number < 20) {
Toast.makeText(getApplicationContext(),
"You entered: " + number, Toast.LENGTH_LONG).show();
for (int i = 0; i <= number; i++) {
fibList.add(fib(i));
// sum even numbers
if (fib(i) % 2 == 0) {
tmp += fib(i);
}
}
} else {
Toast.makeText(getApplicationContext(),
"Number is too Large: " + number, Toast.LENGTH_LONG)
.show();
}
String array = fibList.toString();
textView.setText(array);
}
});
}
// run fibonacci sequence
public static int fib(int n) {
if (n < 2) {
return n;
} else {
return fib(n - 1) + fib(n - 2);
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
you will need to clear textView on Button click event before adding new results to it.do it as:
button1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
textView.setText(""); //<<<<<< clear TextView on Button Click
.....
The problem is more likely in fibList that is not being cleared
Related
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]);
}
I'm a little new to Android. Working on an app that let's user input a number and then calculates the Fibonacci Sequence and then displays each element in the sequence at 1 second intervals. But I have an issue when I try to display using a thread inside a for loop. I try print from an array list but it gives me an error with my counter variable (j). I tried running this same exact method in a much simpler app and the array list worked just fine. I don't know why it doesn't work this time. I hope this is a simple obvious error. Can anyone tell me why? Code is posted below:
public class MainActivity extends Activity {
// primary widgets
private EditText editText;
private TextView textView;
private Button button1;
Thread thread;
static ArrayList<Integer> fibList = new ArrayList<Integer>();
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = (EditText) findViewById(R.id.editText1);
textView = (TextView) findViewById(R.id.textView2);
button1 = (Button) findViewById(R.id.button1);
//Attempt to clear TextView
textView.setText("");
button1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
//Clear Textview
String array = " ";
fibList.clear();
textView.setText(array);
final String input = editText.getText().toString();
int number = Integer.parseInt(input);
int tmp = 0;
// confirm input
if (number < 20) {
Toast.makeText(getApplicationContext(),
"You entered: " + number, Toast.LENGTH_LONG).show();
for (int i = 0; i <= number; i++) {
fibList.add(fib(i));
// sum even numbers
if (fib(i) % 2 == 0) {
tmp += fib(i);
}
}
} else {
Toast.makeText(getApplicationContext(),
"Number is too Large: " + number, Toast.LENGTH_LONG)
.show();
}
Log.i("TEST", "ARRAY"+fibList);
thread = new Thread(new Runnable(){
#Override
public void run(){
for(int j = 0; j < fibList.size(); j++){
runOnUiThread(new Runnable(){
#Override
public void run(){
//ERROR OCCURS HERE: Cannot refer to a non-final variable j
//inside an inner class defined in a different method
textView.append(fibList.get(j).toString());
textView.append("");
}
});
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} //wait one second
}
}
});
thread.start();
}
});
}
// run fibonacci sequence
public static int fib(int n) {
if (n < 2) {
return n;
} else {
return fib(n - 1) + fib(n - 2);
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
a simple workaround to solve your issue is to declare a temp final variable in this way:
for(int j = 0; j < fibList.size(); j++){
final int finalJ = j;
runOnUiThread(new Runnable(){
#Override
public void run(){
//ERROR OCCURS HERE: Cannot refer to a non-final variable j
//inside an inner class defined in a different method
textView.append(fibList.get(finalJ).toString());
textView.append("");
}
});
You have a more serious problem.
You are attempting to manipulate a texView from a thread. That's not permitted. Only the GUI thread can manipulate screen objects or else Bad Things Happen.
Take a look at AsyncTask. It is designed to address exactly the problem you are trying to solve.
http://developer.android.com/reference/android/os/AsyncTask.html
The purpose of my app is: User enters a number and clicks a button. The button uses the input to calculate the Fibonacci sequence with a timer - with each number in the sequence displaying each second to a textView. But when I try to run the timer I get the CalledFromWrongThreadException. I've posted my code below. As you can tell by my log statements I believe I know which line is causing the problem. I think it's because I'm calling a method which is outside my onclicklistener but when I move that other method around I just cause more problems.
I've read a couple other posts and I'm not really sure what the proper way is to print to a text area using my method. Does anyone know how I can make this work?
public class MainActivity extends Activity {
// primary widgets
private EditText editText;
private TextView textView;
private Button button1;
static int seconds = 0;
static Timer timer;
static ArrayList<Integer> fibList = new ArrayList<Integer>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = (EditText) findViewById(R.id.editText1);
textView = (TextView) findViewById(R.id.textView2);
button1 = (Button) findViewById(R.id.button1);
final int delay = 1000;
final int period = 1000;
timer = new Timer();
//Attempt to clear TextView
textView.setText("");
button1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
//Clear Textview
String array = " ";
fibList.clear();
textView.setText(array);
//Log.i("ARRAY", "ATTEMPT to CLEAR"+fibList);
String input = editText.getText().toString();
int number = Integer.parseInt(input);
int tmp = 0;
// confirm input
if (number < 20) {
Toast.makeText(getApplicationContext(),
"You entered: " + number, Toast.LENGTH_LONG).show();
for (int i = 0; i <= number; i++) {
fibList.add(fib(i));
// sum even numbers
if (fib(i) % 2 == 0) {
tmp += fib(i);
}
}
} else {
Toast.makeText(getApplicationContext(),
"Number is too Large: " + number, Toast.LENGTH_LONG)
.show();
}
//I believe error occurs in this method
Log.i("TEST", "START TIMER");
timer.scheduleAtFixedRate(new TimerTask() {
public void run() {
Log.i("TEST", "RUN TIMER");
int nextIndex = setInterval();
Log.i("TEST", "SET INTERVAL");
if (nextIndex < fibList.size()) {
Log.i("TEST", "TRY TO PRINT");
//It looks like error occurs here when I try to print to textView
textView.setText(fibList.get(nextIndex)+ " ");
Log.i("TEST", "NEXT INDEX"+fibList.get(nextIndex));
Log.i("TEST", "DID PRINT");
}
}
}, delay, period);
Log.i("TEST", "END TIMER");
}
});
}
// run fibonacci sequence
public static int fib(int n) {
if (n < 2) {
return n;
} else {
return fib(n - 1) + fib(n - 2);
}
}
//counts up for every element through the array
public static final int setInterval() {
if (seconds >= fibList.size())
timer.cancel();
return seconds++;
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
You can use
runOnUiThread(new Runnable(){
public void run(){
textView.setText("aaa");
}
});
Have your timer post a message to a Handler. The handler will, by default, run on the main thread. IT can then change the UI as needed, so just put the body of your timer into that handler.
I just had this problem and came on to StackOverflow to check out a solution. Didn't find anything proper but a little more experimenting with lot many Logs and debugging got me my solution.
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
textView.setText("Your String");
}
});
In my code, the problem was due to me accessing Two TextViews in seperate threads one after another using TextView.post(new Runnable...). I guess this was due to it not being able to access UI Thread (as it was busy with previous thread changes). Setting both TextViews together in UI Thread solved the problem. So posting here for anyone else who might be perplexed by similar problem. Hope it helps.
This code creates a seekbar and makes the seekbar create as many EditText fields as the slider is at / remove ones that would be too much. This code is in OnActivityCreated
final LinearLayout linearLayout = (LinearLayout) getActivity()
.findViewById(R.id.npv_calcfields);
EditText editText = new EditText(getActivity());
editText.setId(i);
editText.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));
SeekBar bar = (SeekBar) getActivity().findViewById(R.id.npv_seekbar);
final TextView selection = (TextView) getActivity()
.findViewById(R.id.npv_selected);
bar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
public void onProgressChanged(SeekBar seekbar, int progress,
boolean fromUser) {
selection.setText("You have selected " + progress + " periods.");
if (progress == 0) {
String normalstring = getActivity().getResources()
.getString(R.string.npv1);
selection.setText(normalstring);
}
if (i > progress) {
while (i > progress) {
i--;
EditText editText = (EditText) getActivity()
.findViewById(i);
linearLayout.removeView(editText);
}
} else {
while (i < progress) {
EditText editText = new EditText(getActivity());
editText.setId(i);
editText.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
linearLayout.addView(editText);
editText.setHint("Cash Flow " + i);
i++;
}
}
}
public void onStopTrackingTouch(SeekBar arg0) {
}
public void onStartTrackingTouch(SeekBar arg0) {
}
});
This code is in the general class area:
int i = 0;
EditText r = (EditText) getActivity().findViewById(R.id.npv_rate);
Button calc = (Button) getActivity().findViewById(R.id.npv_calc);
EditText[] DynamicField = new EditText[16];
Now I want users to input numbers into those edittext fields and then I want to do some math on them: Entry / (Math.pow(1+r, i) with i beeing the id of the field. The first entry should therefore be calculated as this: entry/(1+r)^0. This is what I tried but it doesn't work. It just crashes on startup.
calc.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
Double r1 = Double.parseDouble(r.getText().toString());
EditText editText = (EditText) getActivity().findViewById(i);
TextView answer = (TextView) getActivity().findViewById(R.id.npv_answer);
double[] CashFlows;
CashFlows = new double[i];
double result = 0;
CashFlows[i] = (Double.parseDouble(editText.getText()
.toString())) / (Math.pow(1 + r1, i));
for (double d : CashFlows) {
result += d;
}
answer.setText("answer is " + result);
}
});
What did I do wrong? by the way only the last code segment isnt working. if i comment that out it all works fine i tested it :) just dosent do anything obviuosly :)
ok a little background on the errorlog that you can see here: http://pastebin.com/G8iX6Pkm
EDIT: the entire class file can be seen here: http://pastebin.com/dxA91dst, the entire project can be found here: https://github.com/killerpixler/Android-Financial-Calculator.git
the class file is a fragment that gets loaded in a DetailsActivity when somebody clicks on a listitem from the Main activity. Like i said the error has to be in the button listener because it was working before i added it.
That NullPointerException comes from the fact that you initialize your Views using the getActivity() method where you declare them as fields in the F_NPV class. The method getActivity() method will return a valid Activity reference after the callback onAttach() is called, so the way you initialize the views will not work as, at that moment(when the fields of the Fragment class are initialized) the method getActivity will return null, no valid reference. The correct way to do that initialization is doing it in the onActivityCreated callback:
EditText r;
Button calc;
//...
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
r = (EditText) getActivity().findViewById(R.id.npv_rate);
calc = (Button) getActivity().findViewById(R.id.npv_calc);
//...
Also, if I may, some suggestions regarding your code:
You're doing some double's parsing from Strings and it may be a good idea to check the input so you don't throw a NumberFormatException. For example, if the user creates some EditTexts and then clicks the calculate Button(I know, it sounds silly, but there are chances the user will do it(I did it for example)), you'll throw a NumberFormatException as you try to parse an empty String. Instead make a little check:
public void onClick(View arg0) {
Double r1 = Double.parseDouble((r.getText().toString())
.equals("") ? "0" : r.getText().toString());
EditText editText = (EditText) getActivity().findViewById(i);
TextView answer = (TextView) getActivity().findViewById(R.id.npv_answer);
double[] CashFlows;
CashFlows = new double[i];
double result = 0;
String tmp = editText.getText().toString();
CashFlows[i] = (Double.parseDouble(tmp.equals("") ? "0" : tmp))
/ (Math.pow(1 + r1, i));
//...
Also, even if you have correct values in the EditText the above code will throw a NullPointerException, as the editText variable will be null. The reason for this is in the while loops that you used to create the fields. For example, if the user moves the SeekBar to 3 than the while loop will run 3 times, each time incrementing the i value. So i will be 0, 1, 2, so far correct but because you increment i each time the final i will be 4. Now in the onClick method you'll look for an EditText with the id i, but as there is no EditText in the layout with the id 4, the view will be null.
Also, try to give your classes better names, you may know very well what they mean but you could be making things worse for someone that reads your code(like F_PNV, F_PV etc).
Code for the onActivityCreated method. This should solve what you're trying to do(if I understand what you want):
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
r = (EditText) getActivity().findViewById(R.id.npv_rate);
calc = (Button) getActivity().findViewById(R.id.npv_calc);
final LinearLayout linearLayout = (LinearLayout) getActivity()
.findViewById(R.id.npv_calcfields);
SeekBar bar = (SeekBar) getActivity().findViewById(R.id.npv_seekbar);
final TextView selection = (TextView) getActivity().findViewById(
R.id.npv_selected);
bar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
public void onProgressChanged(SeekBar seekbar, int progress,
boolean fromUser) {
selection
.setText("You have selected " + progress + " periods.");
if (progress == 0) {
String normalstring = getActivity().getResources()
.getString(R.string.npv1);
selection.setText(normalstring);
linearLayout.removeAllViews(); // the progress is 0 so
// remove all the views that
// are currently present
} else {
int currentChilds = linearLayout.getChildCount();
if (currentChilds < progress) {
while (currentChilds != progress) {
EditText editText = new EditText(getActivity());
editText.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
linearLayout.addView(editText);
currentChilds++;
}
} else if (currentChilds > progress) {
while (currentChilds != progress) {
linearLayout.removeViewAt(linearLayout
.getChildCount() - 1);
currentChilds--;
}
}
}
}
public void onStopTrackingTouch(SeekBar arg0) {
}
public void onStartTrackingTouch(SeekBar arg0) {
}
});
calc.setOnClickListener(new OnClickListener() {
public void onClick(View view) {
Double r1 = Double.parseDouble((r.getText().toString())
.equals("") ? "0" : r.getText().toString());
TextView answer = (TextView) getActivity().findViewById(
R.id.npv_answer);
final LinearLayout linearLayout = (LinearLayout) getActivity()
.findViewById(R.id.npv_calcfields);
int size = linearLayout.getChildCount();
double[] CashFlows = new double[size];
double result = 0;
for (int i = 0; i < size; i++) {
EditText editText = (EditText) linearLayout.getChildAt(i);
String tmp = editText.getText().toString();
CashFlows[i] = (Double.parseDouble(tmp.equals("") ? "0"
: tmp)) / (Math.pow(1 + r1, i));
}
for (double d : CashFlows) {
result += d;
}
answer.setText("answer is " + result);
}
});
}
I am doing an application in which I have to display the numbers on TextView randomly and automatically with the help of Timer. I am able to get the random Numbers in the log without repeating, but I am not able to print the same on device please help me...
Regards,
Akki
Source:
//RandomNumber.java
public class RandomNumber extends Activity{
static Random randGen = new Random();
int tambolanum,count=0;
private Button previousbutton;
private Button startbutton;
private Button nextbutton;
int bingonum[]=new int[90];
boolean fill;
#Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.numbers);
LinearLayout number=(LinearLayout)findViewById(R.id.numbersview);
final TextView randomnum=(TextView)findViewById(R.id.numberstext);
previousbutton=(Button)findViewById(R.id.previous);
nextbutton=(Button)findViewById(R.id.next);
startbutton=(Button)findViewById(R.id.start);
startbutton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// Perform action on click
//--- Initialize the array to the ints 0-90
do{
fill = true;
//Get new random number
tambolanum = randGen.nextInt(90) + 1;
//If the number exists in the array already, don't add it again
for(int i = 0; i < bingonum.length; i++)
{
if(bingonum == tambolanum)
{
fill = false;
}
}
//If the number didn't already exist, put it in the array and move
//To the next position
if(fill == true)
{
bingonum[count] = tambolanum;
count++;
}
} while(count < 90);
for(i=0;i
{
randomnum.setText(Integer.toString(bingonum[i]);
}
}
setText(CharSequence text)
The problem you're having is that you're overwriting your text in every itteration of this loop:
for(i=0;i
{
randomnum.setText(Integer.toString(bingonum[i]);
}
You need to build your string first then set it. Something like:
StringBuilder sb = new StringBuilder();
for(i=0;i /* where's the rest of this for-statement? */
{
sb.append(Integer.toString(bingonum[i]);
}
randomnum.setText(sb.toString());