Develop Reference

Nothing happens when I click on Button except when the EditText is empty

am new in android and facing a problem in edit text view need your help. I just want to check EditText before going on next intent. If EditText is filled by at least 1 String then it will go to next intent. May be this is simple for you to implement but this is to difficult for me and I wasted half day on this. Is anyone here which can tell me where is the mistake in this code.
Thank you in advance
package com.example.tricknearn;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class Posttittle extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_posttittle);
final EditText tittleInput = (EditText) findViewById(R.id.tittleInput);
Button postTittleButton = (Button) findViewById(R.id.postTittleButton);
postTittleButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (tittleInput.getText().length() == 0) {
tittleInput.setError("Please enter some text");
}
}
});
}
public void postTittleClick(View view) {
EditText tittleInput = (EditText) findViewById(R.id.tittleInput);
Intent i = new Intent(this, Postdescription.class);
if (tittleInput.getText().toString().equals("")){
}else{
startActivity(i);
}
}
}

Try this code instead...
public void postTittleClick(View view) {
EditText tittleInput = (EditText) findViewById(R.id.tittleInput);
Intent i = new Intent(this, Postdescription.class);
if (tittleInput.getText().toString().isEmpty()){
// Here you can place code while edit text is empty
}else{
startActivity(i);
}
}

postTittleButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (tittleInput.getText().toString().isEmptry()) {
//edittext is empty
tittleInput.setError("Please enter some text");
} else {
//Edittext is not empty
//start new Activity
}
}
});
And remove postTittleClick method

Replace if (tittleInput.getText().length() == 0) with if (tittleInput.getText().toString.equals(""))

Closing Android Game After 5 Seconds

I'm tring to build an simple android game.
Users answer the questions, when the answer is correct, it is continue..
I want to add time control for each answer.
I tried to add handler function, but I didn't.
My Code;
import java.util.Collections;
import java.util.Arrays;
import java.util.List;
import java.util.Random;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class EasyGameActivity extends Activity {
public int score = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_easygame);
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
public void run() {
finishScreen();
}
}, 5000);
startGame();
}
private void startGame() {
// TODO Auto-generated method stub
Button b1 = (Button)findViewById(R.id.answer_one);
Button b2 = (Button)findViewById(R.id.answer_two);
Button b3 = (Button)findViewById(R.id.answer_three);
Button b4 = (Button)findViewById(R.id.answer_four);
Random number = new Random();
int first = number.nextInt(100)+1;
int second = number.nextInt(100)+1;
int answer = first + second;
int rnd1 = answer + 1;
int rnd2 = answer + 2;
int rnd3 = answer - 1;
final String a = Integer.toString(answer);
String b = Integer.toString(rnd1);
String c = Integer.toString(rnd2);
String d = Integer.toString(rnd3);
((TextView) findViewById(R.id.display)).setText(Integer.toString(first) + '+' + Integer.toString(second));
List<Button> buttons = Arrays.asList(b1, b2, b3, b4);
List<String> texts = Arrays.asList(a, b, c, d);
Collections.shuffle(texts);
int i = 0;
OnClickListener onClick = new OnClickListener() {
public void onClick(View view) {
Button button = (Button) view;
String value = (String) button.getText();
if(value == a) {
checkTrue();
} else {
finishScreen();
}
}
};
for(Button button : buttons) {
button.setText(texts.get(i++));
button.setOnClickListener(onClick);
}
}
private void checkTrue() {
score++;
((TextView) findViewById(R.id.score)).setText(Integer.toString(score));
startGame();
}
private void finishScreen() {
score = 0;
startActivity (new Intent("com.bsinternet.mathfast.RESTARTGAMESCREEN"));
finish();
}
}
How can I add time control. Thanks.

This bit of code doesn't look right
if(value == a) {
checkTrue();
} else {
finishScreen();
}
You should be using equals() to check for String equality. At the moment you are checking only object equality, which will evaluate to False, and the code will never call checkTrue().
Do this instead:
if(value.equals(a) {
checkTrue();
} else {
finishScreen();
}

Why does Text = null?

I am new to Android and Java and don't know why the Text value is null after I assign Text to it? This is a project for University They didn't teach us Java only gave us Eclipse and Android Sdk and Java need some help please!
package com.example.glossaryapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class Syntax extends Activity {
static String Text;
public static TextItem[] Syntax = new TextItem[50];
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.syntax);
final TextView show = (TextView) Syntax.this
.findViewById(R.id.textViewSyn);
// Linking the text View widget
int Count1 = 0;
// Using the TextView's shows method set text to display the appropriate
// arrays and indexes
if (Syntax[0] != null) {
Text = Syntax[0].displayText();
show.setText(Text);
}
// The Add button for if a user wants to add a new TextItem to the Array
Button but1 = (Button) findViewById(R.id.butAddSyntax);
but1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Create.strSender = "Syntax1";
startActivity(new Intent(Syntax.this, Create.class));
}// end of on click
});// butAddSyntax
// Home Button
Button but2 = (Button) findViewById(R.id.buttHomeSyntax);
but2.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
finish();
}// end of on click
});// buttonHomeSyntax
}
public void onResume() {
super.onResume();
TextView show = (TextView) Syntax.this.findViewById(R.id.textViewSyn);
if (Syntax[0] != null) {
Text = Syntax[0].displayText().toString();
show.setText(Text);
}
}
}

Using Android's LogCat will help you to solve this kind of problems.
Here you have a nice article:
http://www.vogella.com/tutorials/AndroidLogging/article.html
I think the problem is in here:
if( Syntax[0] != null ){
Text = Syntax[0].displayText();
show.setText(Text);
}
you could begin using LogCat trying this:
if( Syntax[0] != null ){
Log.d("MyApp", "Sintax (0) = " + Syntax[0].displayText());
Text = Syntax[0].displayText();
show.setText(Text);
} else Log.d("MyApp", "Nothing ");
And watch the result in the Logcat pane.

Factorial program in android

Hey guys I know there are many java programs for the factorial of a number...but I am facing problem with android. Following is my code....Thanks
package com.droidacid.apticalc.aptitudes;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import com.droidacid.apticalc.R;
public class AptiFactorial extends Activity implements android.view.View.OnClickListener{
EditText number;
TextView answer;
Button calculate;
long factorial = 1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.apti_factorial);
initialize();
calcFactorial();
}
private void initialize() {
number = (EditText) findViewById(R.id.et_apti_number);
answer = (TextView) findViewById(R.id.tv_apti_answer);
calculate = (Button) findViewById(R.id.b_apti_calc);
calculate.setOnClickListener(this);
}
private void calcFactorial() {
if (number.getText().toString().equals("")) number.setText("0");
int num = Integer.parseInt(number.getText().toString());
for(int i = 1; i<=num; i++){
factorial = i * factorial;
}
}
#Override
public void onClick(View v) {
calcFactorial();
answer.setText("Factorial of " + number.getText().toString() + " is : " + factorial);
}
}
This is my code and I need to know a way around for setting the hint instead of 0, but if I remove if (number.getText().toString().equals("")) number.setText("0");
then getting NullPointerException...
Also on the first go its calculating correctly but If I calculate again then getting wrong answer. I think some loop issue because I am directly using the value of factorial.
Please help thanks

Forget all that equal stuff, cover all basis and do it like this:
package com.droidacid.apticalc.aptitudes;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import com.droidacid.apticalc.R;
public class AptiFactorial extends Activity implements android.view.View.OnClickListener{
EditText number;
TextView answer;
Button calculate;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.apti_factorial);
initialize();
}
private void initialize() {
number = (EditText) findViewById(R.id.et_apti_number);
number.setHint("Enter number to be factorialized :P")
answer = (TextView) findViewById(R.id.tv_apti_answer);
calculate = (Button) findViewById(R.id.b_apti_calc);
calculate.setOnClickListener(this);
}
private long calcFactorial() {
long factorial = 1;
try {
factorial = Long.parseLong(number.getText().toString());
for(int i=factorial-1; i>0; i--){
factorial = i * factorial;
}
} catch (NumberFormatException e) {
Toast.makeText(this, "Incorrect Input", Toast.LENGTH_LONG).show();
} finally {}
return factorial;
}
#Override
public void onClick(View v) {
answer.setText("Factorial of " + number.getText().toString() + " is : " + calcFactorial());
}

Do something like.
private void calcFactorial() {
int num = 0;
if (!number.getText().toString().equals(""))
num = Integer.parseInt(number.getText().toString());
for(int i = 1; i<=num; i++){
factorial = i * factorial;
}
}

Rather than using
(number.getText().toString().equals("")) number.setText("0");
Use
(number.getText().length==0) number.setText("0");

** first go its calculating correctly but If I calculate again then getting wrong answer**
try like this
private void calcFactorial() {
factorial = 1;///Check out the line..
int num = 0;
if (!number.getText().toString().equals(""))
num = Integer.parseInt(number.getText().toString());
for(int i = 1; i<=num; i++){
factorial = i * factorial;
}
}
You need to make sure variable factorial is reinitialise to 1 .. for getting factorial for next number..

private void fact_isClicked(View view) {
if(textField.length()>0){
int ifac = Integer.parseInt(textField.getText().toString());
int fact = factorial(ifac);
tvsec.setText(String.valueOf(fact));
textField.setText(ifac+"!");
}}

What is wrong with my android simple calculator app?

I'm new to android and this is my first application, it seems fine to me but every time I pressed the calculate button it seems to stop unexpectedly and force close.
package com.test.simplecalc;
import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final Button myButton = (Button) findViewById(R.id.myButton);
final EditText firstNum = (EditText)findViewById(R.id.firstNum);
final EditText secondNum = (EditText)findViewById(R.id.secondNum);
final EditText finalNum = (EditText)findViewById(R.id.finalNum);
myButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
int num1 = 0;
try {
num1 = Integer.parseInt(firstNum.getText().toString());
} catch(NumberFormatException nfe) {
Toast.makeText(MainActivity.this, "Could not parse" + nfe, Toast.LENGTH_SHORT).show();
}
int num2 = 0;
try {
num2 = Integer.parseInt(secondNum.getText().toString());
} catch(NumberFormatException nfe) {
Toast.makeText(MainActivity.this, "Could not parse" + nfe, Toast.LENGTH_SHORT).show();
}
int num3 = num1 + num2;
finalNum.setText(num3);
}
});
}
}

It's likely that one of the two blocks is throwing something other than NumberFormatException. (My guess would be a NullPointerException in the call to toString().)
Try changing the caught exception in each case to Exception and see if this reveals the problem.

just try
num3.toString()
while printing the answer, and better to use textview for showing answer