I'm pretty new to Android's Java (so please don't beat me up) and I have a question to my button action. The called method is running only one time. When I click the button the second time nothing happens anymore. I do not understand why. No errors, no flaws, the method is doing what is expected. Any hints?
Thanks!
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
TextView mainFortuneTextView;
Button mainFortuneButton;
private int counter, i, x;
//private int randomNumber;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// 1. Access the TextView defined in layout XML
// and then set its text
mainFortuneTextView = (TextView) findViewById(R.id.fortuneTextView);
// 2. Access the Button defined in layout XML
// and listen for it here by using "this"
mainFortuneButton = (Button) findViewById(R.id.fortuneButton);
mainFortuneButton.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// happens on button action in main view
runThread();
Random rnd = new Random();
x = rnd.nextInt(11) + 1;
}
private void runThread() {
mainFortuneButton.setEnabled(false);
new Thread() {
public void run() {
while (i++ < 10) {
try {
runOnUiThread(new Runnable() {
#Override
public void run() {
mainFortuneTextView.setText("#" + i);
}
});
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
// activate button again
runOnUiThread(new Runnable() {
#Override
public void run() {
mainFortuneButton.setEnabled(true);
}
});
}
}.start();
}
}
Your variable i used in your while is a field. That means that it will not reset. That's why the second time you call your thread the i value will be 10 and it will be called not again. You have to reset your i again before starting a new thread.
Related
I'm very new to Android development. Can anyone help me with this snippet, I don't know why it works perfectly although I'm updating my TextView from the worker thread.
When I say works perfectly, I mean the TextView shows the value count without any problem.
So, My question is - "Is it really possible to update the UI from background thread and if not, where I'm wrong"
public class MainActivity extends AppCompatActivity {
TextView textView ;
private int count;
Button btn;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = findViewById(R.id.textview);
btn = findViewById(R.id.startbtn);
btn.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v) {
listen();
}
});
}
public void listen(){
new Thread(new Runnable() {
#Override
public void run() {
long time = System.currentTimeMillis();
while(System.currentTimeMillis()<=time +10000) {
count++;
}
textView.setText(count+"");
}
}).start();
}
}
Use
runOnUiThread(new Runnable() {
#Override
public void run() {
// Add UI code here
}
});
All UI updates should be done on the main thread.
Goal:
When you start the android app, the button should not be displayed after 5 seconds.
Problem:
The code doesn't work and what part am I missing?
Info:
*Im new in android
*The code is inspired from this page Android - Hide button during an onClick action
Thank you!
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Button button2 = (Button) findViewById(R.id.btn_test);
button2.setVisibility(GONE);
new Thread(new Runnable() {
#Override
public void run() {
try
{
//dummy delay for 5 second
Thread.sleep(5000);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
runOnUiThread(new Runnable() { //resetting the visibility of the button
#Override
public void run() {
//manipulating UI components from outside of the UI Thread require a call to runOnUiThread
button2.setVisibility(VISIBLE);
}
});
}
}).start();
}
}
This can be achieved in a simpler way. If your needed sequence is:
Start the app -> Display a button -> Wait 5 seconds -> Hide the button
final Button button2 = (Button) findViewById(R.id.btn_test);
button2.postDelayed(new Runnable() {
#Override
public void run() {
if (!isDestroyed() && !isFinishing()) {
button2.setVisibility(View.GONE);
}
}
},5000);
Otherwise, if you should display the button after 5 seconds after app launch, then just set button's visibility to GONE in your layout and change button2.setVisibility(View.GONE) to button2.setVisibility(View.VISIBLE) inside post delayed action
You need to set a listener to start your command, onCreate is the creation.
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final Button button2 = (Button) findViewById(R.id.btn_test);
button2.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
button2.setVisibility(GONE);
new Thread(new Runnable() {
#Override
public void run() {
try
{
//dummy delay for 5 second
Thread.sleep(5000);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
runOnUiThread(new Runnable() { //resetting the visibility of the button
#Override
public void run() {
//manipulating UI components from outside of the UI Thread require a call to runOnUiThread
button2.setVisibility(VISIBLE);
}
});
}
}).start();
}
this code will hide the button AFTER onClick, start the thread, and after 5 seconds it will appear again.
My goal is when the user tap start button, letters "o" "n" "o" "m" and so forth will appear at the center of the screen. "o" will appear first then after a few seconds will be replaced by "n" then "o" and so forth.
note: for brevity, i just make the guessword = onomatopoeia, first. In reality, guessword will changes every time i tap the start bottom.
this is the code:
private String guessword = "onomatopoeia";
private TextView showchar;
private int n = guessword.length();
private char letArray[]= guessword.toCharArray();;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_play);
addStartListener();
}
public void addStartListener(){
Button start = (Button) findViewById(R.id.start);
showchar = (TextView) findViewById (R.id.charView);
start.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Thread thread = new Thread()
{
#Override
public void run() {
try {
for(int i = 0 ; i < n ; i++) {
sleep(1000);
showchar.setText(letArray[i]);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
};
thread.start();
}
});
}
thanks for the help
I decided to implement runonuithread but still it crashes:
this is the updated version:
private String guessword = "onomatopoeia";
private TextView showchar;
private int n = guessword.length();
private char letArray[]= guessword.toCharArray();
private Handler handler;
private int i = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_play);
handler = new Handler();
showchar = (TextView) findViewById (R.id.charView);
}
public void startGame(View view){
new Thread() {
public void run() {
while(i++ < n) {
try {
runOnUiThread(new Runnable() {
#Override
public void run() {
showchar.setText(letArray[i]);
}
});
Thread.sleep(300);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}.start();
}
use this code for setting the text in your textview
runOnUiThread(new Runnable() {
#Override
public void run() {
showchar.setText(letArray[i]);
}
});
You are updating ui from a thread which is not possible.
showchar.setText(letArray[i]);
UI must be updated ui thread.
All you are doing is repeatedly setting value to TextView you can use Handler with a delay for this purpose.
You could use runOnUiThread also but i don't see the need for a thread for what you are doing.
Use a Handler. You can find an example #
Android Thread for a timer
I have three layouts:
Layout1
-->onClick()-->show
Layout2
-->wait three seconds-->show
Layout3
The problem is that Layout2 is not shown. To set the layouts I use
setContentView(int);
The relevant code might be:
public class TrainingActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layout1);
final Button inputButton = (Button)findViewById(R.id.inputButton);
inputButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
changeLayouts();
}
});
}
public void changeLayouts() {
setContentView(R.layout.layout2);
try {
TimeUnit.MILLISECONDS.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
setContentView(R.layout.layout3);
}
}
My idea was that Android might use something like an "Event-Loop" (like Qt) and my method would block the control to get back to the "Event-Loop" which would make the layout displayed.
But I couldn't find my error.
The problem why your layout2 is not shown is because of TimeUnit.MILLISECONDS.sleep(3000); - what you are doing here is you put your UI thread into sleep, so UI thread cannot process your request to change layout. And when it wakes up - it immediately sets layout3 that's why layout2 is not shown.
You might consider using Handler.postDelayed(Runnable, long) to postpone execution
So this should work as you expected:
public class TrainingActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layout1);
final Button inputButton = (Button)findViewById(R.id.inputButton);
inputButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
changeLayouts();
}
});
}
public void changeLayouts() {
setContentView(R.layout.layout2);
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
setContentView(R.layout.layout3);
}
}, 3000);
}
}
Try this, it will surely work
public void changeLayouts() {
setContentView(R.layout.layout2);
Thread Timer = new Thread(){
public void run(){
try{
sleep(3000);
} catch(InterruptedException e){
e.printStackTrace();
} finally {
setContentView(R.layout.layout3);
}
}
}; Timer.start();
}
i creating for stopwatch with start,stop i use following code it started but not stop. please help me.
my code:
public class StopWatch2 extends Activity implements Runnable{
// text view influenced by the Thread
private TextView threadModifiedText;
int time=0;
Button b1,b2,b3;
/** Called when the activity is first created. */
Thread currentThread = new Thread(this);
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.stopwatch);
b1=(Button)findViewById(R.id.button1);
b2=(Button)findViewById(R.id.button2);
b3=(Button)findViewById(R.id.button3);
threadModifiedText = (TextView) findViewById(R.id.textView1);
b1.setOnClickListener(new View.OnClickListener()
{
public void onClick(View view)
{
currentThread.start();
}
});
b2.setOnClickListener(new View.OnClickListener()
{
public void onClick(View view)
{
currentThread.stop();
}
});
}
//Method you must override to control what the Thread is doing
#Override
public void run(){
try {
while(true){
currentThread.sleep(1000, 0);
threadHandler.sendEmptyMessage(0);
}
// signaling things to the outside world goes like this
} catch (InterruptedException e) {
}
}
private Handler threadHandler = new Handler() {
public void handleMessage(android.os.Message msg) {
time++;
threadModifiedText.setText(""+time);
}
};
}
I think You should use a class level variable boolean shouldRun = true ;
in your run() method while should be used like this way
while(shouldRun)
{
//implementation
}
and in your b2.onClickListener() change shouldRun = false;
Edit:
For suspend and resume you can change the value of shouldRun to shouldRun = true; in the listener for resume button. Remember that when you stop the updates you should reset the time also. and in suspend the time should be remain same.
I implemented stopwatch for rotational puzzles solving time measurements and I have approached it somewhat differently.
For time measurements I use Handler object that triggers after DISPLAY_UPDATE_TIMEOUT. It is time after which you update display about time elapsed.
To start counting I use:
mLastStartTimestamp = System.currentTimeMillis();
mRepetitiveTimeoutHandler.postDelayed(processWatchTimer, DISPLAY_UPDATE_TIMEOUT);
and to stop it
mRepetitiveTimeoutHandler.removeCallbacks(processWatchTimer);
mStartStopElapsed = System.currentTimeMillis() - mLastStartTimestamp ;
updateTimeDisplay();
On each trigger of the handler I do the following:
private Runnable processWatchTimer = new Runnable()
{
public void run()
{
mRepetitiveTimeoutHandler.postDelayed(processWatchTimer, DISPLAY_UPDATE_TIMEOUT);
updateTimeDisplay();
}
};