I am new to Android. I am showing Text in the TextView on Button click Randomly. On 1st Textview the Heading and on 2nd the explaination of that heading. I am able to show the Heading and Explaination Randomly and now I want if the Text is shown once should not be shown again means it will be removed. This is the point where I stuck. I am not able to remove the texts. Any help will be appreciated. I am posting my code here.
MainActivity.java
TextView text_heading,text_explain;
Button click;
Random random;
Integer [] array_heading ,array_explain ;
Integer int_text;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text_heading = (TextView) findViewById(R.id.text_heading);
text_explain = (TextView) findViewById(R.id.text_explain);
click = (Button) findViewById(R.id.click);
click.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
text_heading.setText(array_heading.get(int_text)); //getting error
text_explain(array_explain.get(int_text)); //getting error
array_heading.remove(int_text); //getting error
array_explain.remove(int_text); //getting error
}
});
random = new Random();
array_heading = new Integer []{R.string.source_text1, R.string.source_text2, R.string.source_text3,
R.string.source_text6, R.string.source_text5, R.string.source_text4, R.string.source_text7,
R.string.source_text8, R.string.source_text9};
array_explain = new Integer []{R.string.source_text1_explain, R.string.source_text2_explain,
R.string.source_text3_explain,
R.string.source_text4_explain, R.string.source_text5_explain, R.string.source_text6_explain,
R.string.source_text7_explain,
R.string.source_text8_explain, R.string.source_text9_explain};
ArrayList<Integer> array_headingList = new ArrayList<Integer>(Arrays.asList(array_heading));
ArrayList<Integer>array_explainList = new ArrayList<Integer>(Arrays.asList(array_explain));
int_text = random.nextInt(array_headingList.size() - 1);
}
}
I am not able to remove the texts. Any help will be appreciated. I am
posting my code here.
To clean the content of the TextView you could pass null to setText. E.g
text_heading.setText(null);
If you want to change the content every time you click on the button, you have to move
int_text = random.nextInt(array_heading.length);
your onClick callback,
You should be aware of the fact that next int returns an int between [0, n). array_heading.length -1 is necessary only if you want to exclude R.string.source_text9_explain from the possible texts you want to show. Keep also in mind that if array_heading contains more items than array_explain you could get ArrayIndexOutBoundException
I would keep the strings together in an object:
public class Item {
private final int textId;
private final int textExplanationId;
public class Item(int textId, int textExplanationId){
this.textId = textId;
this.textExplanationId = textExplanationId;
}
public int getTextId(){return textId;}
public int getTextExplanationId(){return textExplanationId;}
}
Then I would store those in an ArrayList:
List<Item> items = new ArrayList<Item>(new Item[]{
new Item(R.string.source_text1, R.string.source_text1_explain),
new Item(R.string.source_text2, R.string.source_text2_explain),
//etc
});
Then I would shuffle that array once:
Collections.shuffle(items);
And read from it in order:
Item current = items.get(currentIndex++);
text_heading.setText(current.getTextId());
text_explain.setText(current.getTextExplanationId());
TextView text_heading,text_explain;
Button click;
Random random;
Integer [] array_heading ,array_explain ;
Integer int_text;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text_heading = (TextView) findViewById(R.id.text_heading);
text_explain = (TextView) findViewById(R.id.text_explain);
click = (Button) findViewById(R.id.click);
random = new Random();
array_heading = new Integer []{R.string.source_text1, R.string.source_text2, R.string.source_text3,
R.string.source_text6, R.string.source_text5, R.string.source_text4, R.string.source_text7,
R.string.source_text8, R.string.source_text9};
array_explain = new Integer []{R.string.source_text1_explain, R.string.source_text2_explain,
R.string.source_text3_explain,
R.string.source_text4_explain, R.string.source_text5_explain, R.string.source_text6_explain,
R.string.source_text7_explain,
R.string.source_text8_explain, R.string.source_text9_explain};
ArrayList<Integer> array_headingList = new ArrayList<Integer>(Arrays.asList(array_heading));
ArrayList<Integer> array_explainList = new ArrayList<Integer>(Arrays.asList(array_explain));
int_text = random.nextInt(array_headingList.size() - 1);
click.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
text_heading.setText(array_headingList.get(int_text)); //getting error
text_explain.setText(array_explainList.get(int_text)); //getting error
array_headingList.remove(int_text); //getting error
array_explainList.remove(int_text); //getting error
}
});
}
}
You must use ArrayList for it.
ArrayList<Integer> heading = Arrays.asList(array_heading);
ArrayList<Integer> explain = Arrays.asList(array_explain);
Now set text from this arraylists. And when its set once remove it from the arraylist so it cannot be shown again.
Use like this
random = new Random();
array_heading = new Integer []{R.string.source_text1, R.string.source_text2, R.string.source_text3,
R.string.source_text6, R.string.source_text5, R.string.source_text4, R.string.source_text7,
R.string.source_text8, R.string.source_text9};
array_explain = new Integer []{R.string.source_text1_explain, R.string.source_text2_explain,
R.string.source_text3_explain,
R.string.source_text4_explain, R.string.source_text5_explain, R.string.source_text6_explain,
R.string.source_text7_explain,
R.string.source_text8_explain, R.string.source_text9_explain};
ArrayList<Integer> array_headingList = new ArrayList<Integer>(Arrays.asList(array_heading));
ArrayList<Integer> array_explainList = new ArrayList<Integer>(Arrays.asList(array_explain));
int_text = random.nextInt(array_headingList.size());
click.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
text_heading.setText(array_headingList.get(int_text));
text_explain.setText(array_explainList.get(int_text));
array_headingList.remove(int_text);
array_explainList.remove(int_text);
if(array_headingList.size() == 0){
click.setEnabled(false);
Toast.makeText(getApplicationContext(),"All text finished",Toast.LENGTH_SHORT).show();
} else if(array_headingList.size() == 1){
int_text = 0;
} else {
int_text = random.nextInt(array_headingList.size());
}
}
});
In an android app I intend to allow users to answer a random sum then a new one appears on screen. This is repeated 10 times and then a final score will then be given. However I am unsure how to update the sum so that after each each a new random is shown on screen.
Below is my current code:
public class Test extends Activity {
//declare vars
TextView text;
EditText answer;
Button submit;
int random1;
int random2;
String question;
int correctAnswer;#
Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test);
// initialising variables
initialiseVars();
//set up random
setUpRandom();
//Set text view equal to question
text.setText(question);
//updateQuestion?
}
public void initialiseVars() {
text = (TextView) findViewById(R.id.tvTopRandomTest);
answer = (EditText) findViewById(R.id.etEnterAnswerRandomTest);
submit = (Button) findViewById(R.id.btnSubmitRandomTest);
}
public void setUpRandom() {
//setting up randoms
Random random = new Random();
// Generating random number between 1 and 12
random1 = random.nextInt(12) + 1;
// Generating another random number between 1 and 12
random2 = random.nextInt(12) + 1;
question = random1 + " x " + random2 + " = ";
correctAnswer = random1 * random2;
}
public void updateQuestion() {
//CODE TO UPDATE QUESTION
}
}
Add Button ClickListener so that when user press submit button it will update question and clean all previous values
submit = (Button) findViewById(R.id.btnSubmitRandomTest);
submit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
updateQuestion();
}
}
Maintain a count in your activity and increase it in updateQuestion
public void updateQuestion() {
if (Int.parseString(answer.getText().toString()) != correctAnswer) {
// Show toast or something
return;
}
tries++;
if (tries == 10) return; // or do something else;
answer.setText("");
setUpRandom();
text.setText(question); // add this line in your setUpRandom();
}
To generate random integers look at this. Hopefully this will help you out.
When edittext is null and press add button my code crash...I try to copy integers from edittext to an Array...How i can fix it this error? i have set edittext
android:inputType="numberDecimal"
Can i put try...catch?
public static ArrayList<Integer> pulseslist = new ArrayList<Integer>();
public int pulses1[]=null;
private OnClickListener btnAddListener = new OnClickListener() {
public void onClick(View v) {
String ag=editIRpulse1.getText().toString().trim();
if (ag!=null){
int intag= Integer.parseInt(ag);
if(ag.length() > 0){
pulseslist.add(intag);
editIRpulse1.setText(""); // adds text to arraylist and make edittext blank again
}
pulses1 = new int[pulseslist.size()];
for (int i = 0; i < pulseslist.size(); i++) {
pulses1[i] = pulseslist.get(i);
}
}
}
};
try this
public static ArrayList<Integer> pulseslist = new ArrayList<Integer>();
public int pulses1[]=null;
private OnClickListener btnAddListener = new OnClickListener() {
public void onClick(View v) {
String ag=editIRpulse1.getText().toString();
if (ag!=null){
ag.trim(); //Maybe crash for this method put here........................
int intag= Integer.parseInt(ag);
if(ag.length() > 0){
pulseslist.add(intag);
editIRpulse1.setText(""); // adds text to arraylist and make edittext blank again
}
pulses1 = new int[pulseslist.size()];
for (int i = 0; i < pulseslist.size(); i++) {
pulses1[i] = pulseslist.get(i);
}
}
}
};
change this
android:inputType="numberDecimal"
to
android:inputType="number"
Since you want only ints. You also should use a try/catch to catch a NumberFormatException to prevent empty Strings or numbers that are invalid. Just don't do nothing if you catch an exception. You should display a message to the user that they have enetered invalid characters
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
What's wrong here ?
Random numbers work well.
Checking the part number also works well.
But when I type a the same number that has been randomly selected is always "Toast Bad".
Code: http://pastebin.com/0pdySnW9
Sorry but i can't paste code here.
In your onClick method you are infact generating another random number.
So the number you are typing in, is NOT going to be equal to the random number, as it is NOT the one displayed on screen.
Depending on what you are trying to achieve.. remove line 32, and make random a global variable.
In your onClick you are generating a new random number with this line
int random = random();
You should make your random variable amember variable so that it can be accessed throughout your activity without changing
ex
public class MainActivity extends Activity implements OnClickListener {
private TextView display;
private Button ok;
public EditText et;
private int random; //note this is now a member variable
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ok = (Button) findViewById(R.id.button1);
ok.setOnClickListener(this);
display = (TextView) findViewById(R.id.textView1);
et = (EditText) findViewById(R.id.etNumbers);
random = random();
display.setText("Random Number:" + random); // Show the random number
}
// ************RANDOM******************************
public static int random() {
Random generator = new Random();
int x = generator.nextInt(100);
return x;
}
// ************************************************
public void onClick(View v) {
// TODO Auto-generated method stub
int numberEntered = -1;
try {
numberEntered = Integer.parseInt(et.getText().toString());
} catch (NumberFormatException nfe) {
Toast.makeText(et.getContext(), "That's not a number!",
Toast.LENGTH_LONG).show();
}
if (random == numberEntered) {
Toast.makeText(et.getContext(), "Great!", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(et.getContext(), "Bad!", Toast.LENGTH_LONG).show();
}
}
}