My app keeps crashing since I started using a TextWatcher...
As you can see below i made a TextWatcher to 3 EditText fields...
And i made a button which listens to the 3 EditText..
If they are empty the button become disabled.
When the fields are filled the button should become enabled..
package com.example.magazijnapp;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.MenuPopupWindow;
import android.content.DialogInterface;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;
import android.widget.Switch;
import android.widget.TextView;
import android.widget.Toast;
import org.w3c.dom.Text;
import java.sql.Array;
public class MainActivity extends AppCompatActivity {
Spinner spinnermagazijn;
Button knop;
private EditText EditTextregisternummerbalk;
private EditText EditTextticketnummerbalk;
private EditText EditTextartikelnummerbalk;
private Button knopconfirm;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
EditTextregisternummerbalk = findViewById(R.id.registernummerbalk);
EditTextticketnummerbalk = findViewById(R.id.ticketnummerbalk);
EditTextartikelnummerbalk = findViewById(R.id.artikelnummerbalk);
knopconfirm = findViewById(R.id.knop);
EditTextregisternummerbalk.addTextChangedListener(invulTextWatcher);
EditTextticketnummerbalk.addTextChangedListener(invulTextWatcher);
EditTextartikelnummerbalk.addTextChangedListener(invulTextWatcher);
}
private TextWatcher invulTextWatcher = new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
String registernummerinput = EditTextregisternummerbalk.getText().toString().trim();
String ticketnummerinput = EditTextticketnummerbalk.getText().toString().trim();
String artikelnummerinput = EditTextartikelnummerbalk.getText().toString().trim();
knopconfirm.setEnabled(!registernummerinput.isEmpty() && !ticketnummerinput.isEmpty() &&! artikelnummerinput.isEmpty());
}
#Override
public void afterTextChanged(Editable s) {
}
};
{
spinnermagazijn = findViewById(R.id.spinnermagazijn);
knop = findViewById(R.id.knop);
populatespinnermagazijn();
// Dit is het stukje voor de Knop afboeken waarmee je een melding genereerd, String aanpassen voor ander resultaat.
knop.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(MainActivity.this, (R.string.succes), Toast.LENGTH_SHORT) .show();
}
});
}
// Dit gedeelte is voor de spinner.
private void populatespinnermagazijn() {
ArrayAdapter<String> magazijnenAdapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_item, getResources().getStringArray(R.array.steunpunten));
magazijnenAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnermagazijn.setAdapter(magazijnenAdapter);
}
}
And this is my logcat...
03-19 21:04:06.293 21151-21151/? E/libprocessgroup: failed to make and chown /acct/uid_10060: Read-only file system
03-19 21:04:06.293 21151-21151/? W/Zygote: createProcessGroup failed, kernel missing CONFIG_CGROUP_CPUACCT?
03-19 21:04:06.293 21151-21151/? I/art: Not late-enabling -Xcheck:jni (already on)
03-19 21:04:06.313 21151-21161/? I/art: Debugger is no longer active
03-19 21:04:06.351 21151-21151/? D/AndroidRuntime: Shutting down VM
03-19 21:04:06.354 21151-21151/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.magazijnapp, PID: 21151
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.magazijnapp/com.example.magazijnapp.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2236)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
at android.content.ContextWrapper.getApplicationInfo(ContextWrapper.java:149)
at android.view.ContextThemeWrapper.getTheme(ContextThemeWrapper.java:99)
at android.content.Context.obtainStyledAttributes(Context.java:437)
at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:692)
at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:659)
at androidx.appcompat.app.AppCompatDelegateImpl.findViewById(AppCompatDelegateImpl.java:479)
at androidx.appcompat.app.AppCompatActivity.findViewById(AppCompatActivity.java:214)
at com.example.magazijnapp.MainActivity.<init>(MainActivity.java:73)
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.Class.newInstance(Class.java:1606)
at android.app.Instrumentation.newActivity(Instrumentation.java:1066)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2226)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
03-19 21:04:07.996 21151-21151/? I/Process: Sending signal. PID: 21151 SIG: 9
There are two findViewById(R.id.knop);
remove this line:
knop = findViewById(R.id.knop);
and change :
knopconfirm.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(MainActivity.this, (R.string.succes), Toast.LENGTH_SHORT) .show();
}
});
You are saying your app is crashing since you started using TextWatcher. So why don't you stop using it?
you can achieve the same thing without using TextWatcher by doing this.
knop.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String registernummerinput = EditTextregisternummerbalk.getText().toString().trim();
String ticketnummerinput = EditTextticketnummerbalk.getText().toString().trim();
String artikelnummerinput = EditTextartikelnummerbalk.getText().toString().trim();
if((!registernummerinput.isEmpty() && !ticketnummerinput.isEmpty() &&! artikelnummerinput.isEmpty())) {
Toast.makeText(MainActivity.this, (R.string.succes), Toast.LENGTH_SHORT) .show();
}
}
});
you will not need any TextWathcer just modify the listner
Related
I am writing code where I need to google search item from textedit from previous screen. But when I press the button to search, android studio crashes, what do I do wrong?
package com.example.myapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class Main2Activity extends AppCompatActivity {
TextView name;
Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
name = findViewById(R.id.textView3);
button = findViewById(R.id.Button2);
String Name = getIntent().getStringExtra("text");
name.setText(name.getText().toString()+ "" + Name);
name.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//https://www.google.com/#q=
startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("https://www.google.com/#q=" + name.getText())));
}
});
}
}
My crash stacktraces:
D/AndroidRuntime: Shutting down VM E/AndroidRuntime: FATAL EXCEPTION:
main Process: com.example.myapplication, PID: 17740
java.lang.IllegalStateException: Could not find method onClick(View)
in a parent or ancestor Context for android:onClick attribute defined
on view class androidx.appcompat.widget.AppCompatButton with id
'Button2' at
androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:436)
at
androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:393)
at android.view.View.performClick(View.java:7125) at
android.view.View.performClickInternal(View.java:7102) at
android.view.View.access$3500(View.java:801) at
android.view.View$PerformClick.run(View.java:27336) at
android.os.Handler.handleCallback(Handler.java:883) at
android.os.Handler.dispatchMessage(Handler.java:100) at
android.os.Looper.loop(Looper.java:214) at
android.app.ActivityThread.main(ActivityThread.java:7356) at
java.lang.reflect.Method.invoke(Native Method) at
com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
I/Process: Sending signal. PID: 17740 SIG: 9 Disconnected from the
target VM, address: 'localhost:8621', transport: 'socket'
You do not define an onClickListerner for your button.
I think name.setOnClickListener must be button.setOnClickListener
BTW: Do not use the same variable name in two different cases:
TextView name; and
String Name =.
By convention variable names should start with lower case character
I am new on android and working on my android app's login activity for which em using php mysql with volley library. But every time I run my app on emulator it shows the message Unfortunately, app has stopped. Here the login activity code is:
package com.example.u.locationtracker;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.HashMap;
import java.util.Map;
public class MainActivity extends AppCompatActivity {
private EditText pass1, email1;
private Button login;
private TextView link_reg;
private ProgressBar loading;
private String URL_LOGIN= "http://192.168.1.1/register.php";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
email1= (EditText) findViewById(R.id.etemail1);
pass1= (EditText) findViewById(R.id.etpassl);
loading= (ProgressBar) findViewById(R.id.loading1);
link_reg= (TextView) findViewById(R.id.signup);
login= (Button) findViewById(R.id.btnlogin);
login.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String mEmail= email1.getText().toString().trim();
String mpass= pass1.getText().toString().trim();
if(!mEmail.isEmpty() || !mpass.isEmpty()){
Login(mEmail, mpass);
}else{
email1.setError("Please Enter Email...!");
pass1.setError("Please Enter Password...!");
}
}
});
link_reg.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent it= new Intent(MainActivity.this, Register.class);
startActivity(it);
}
});
}
private void Login(final String email, final String pass) {
loading.setVisibility(View.VISIBLE);
login.setVisibility(View.GONE);
StringRequest stringRequest= new StringRequest(Request.Method.POST, URL_LOGIN,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
try{
JSONObject jsonObject= new JSONObject(response);
String success= jsonObject.getString("Success");
JSONArray jsonArray= jsonObject.getJSONArray("Login");
if(success.equals("1")){
for (int i= 0; i < jsonArray.length(); i++){
JSONObject object= jsonArray.getJSONObject(i);
Toast t= Toast.makeText(MainActivity.this,
"Login Successful", Toast.LENGTH_LONG);
t.show();
loading.setVisibility(View.GONE);
}
}
}catch (JSONException e) {
e.printStackTrace();
loading.setVisibility(View.GONE);
login.setVisibility(View.VISIBLE);
Toast t1= Toast.makeText(MainActivity.this,
"Error" + e.toString(),
Toast.LENGTH_LONG);
t1.show();
}
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
loading.setVisibility(View.GONE);
login.setVisibility(View.VISIBLE);
Toast t2= Toast.makeText(MainActivity.this,
"Error" + error.toString(),
Toast.LENGTH_LONG);
t2.show();
}
})
{
#Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> params= new HashMap<>();
params.put("Email", email);
params.put("Password", pass);
return params;
}
};
RequestQueue requestQueue= Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
}
According to logcat the problem is:
at com.example.u.locationtracker.MainActivity.onCreate(MainActivity.java:39)
here the php code:
<?php
if ($_SERVER['REQUEST_METHOD']=='POST') {
$email= $_POST['email1'];
$pass= $_POST['pass1'];
require_once 'connect.php';
$select= "SELECT * FROM user_table WHERE Email= '$email' ";
$r= mysqli_query($conn, $select);
$result= array();
$result['login']= array();
if (mysqli_num_rows($r)=== 1) {
$row= mysqli_fetch_assoc($r);
if ( password_verify($pass, $row['Pass']) ) {
$index['Name']= $row['Name'];
$index['Email']= $row['Email'];
array_push($result['login'], $index);
$result['success']= "1";
$result['message']= "Success";
echo json_encode($result);
mysql_close($conn);
}else{
$result['success']= "0";
$result['message']= "Error";
echo json_encode($result);
mysql_close($conn);
}
}
}
?>
Here is the Logcat:
02-03 21:03:21.626 2006-2012/? E/jdwp: Failed writing handshake bytes: Broken pipe (-1 of 14)
02-03 21:03:21.806 2006-2006/? E/dalvikvm: Could not find class 'android.support.v4.view.ViewCompat$OnUnhandledKeyEventListenerWrapper', referenced from method android.support.v4.view.ViewCompat.addOnUnhandledKeyEventListener
02-03 21:03:21.806 2006-2006/? E/dalvikvm: Could not find class 'android.view.WindowInsets', referenced from method android.support.v4.view.ViewCompat.dispatchApplyWindowInsets
02-03 21:03:21.826 2006-2006/? E/dalvikvm: Could not find class 'android.view.WindowInsets', referenced from method android.support.v4.view.ViewCompat.onApplyWindowInsets
02-03 21:03:21.826 2006-2006/? E/dalvikvm: Could not find class 'android.view.View$OnUnhandledKeyEventListener', referenced from method android.support.v4.view.ViewCompat.removeOnUnhandledKeyEventListener
02-03 21:03:21.836 2006-2006/? E/dalvikvm: Could not find class 'android.support.v4.view.ViewCompat$1', referenced from method android.support.v4.view.ViewCompat.setOnApplyWindowInsetsListener
02-03 21:03:22.756 2006-2006/com.example.u.locationtracker E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering
02-03 21:03:27.786 2006-2006/com.example.u.locationtracker E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.u.locationtracker, PID: 2006
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.u.locationtracker/com.example.u.locationtracker.MainActivity}: android.view.InflateException: Binary XML file line #45: Error inflating class ImageView
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2193)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2243)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5019)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.view.InflateException: Binary XML file line #45: Error inflating class ImageView
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:758)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:758)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:758)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
at android.support.v7.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:469)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140)
at com.example.u.locationtracker.MainActivity.onCreate(MainActivity.java:39)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2157)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2243)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5019)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.content.res.Resources$NotFoundException: Resource is not a Drawable (color or path): TypedValue{t=0x1/d=0x7f07005d a=-1 r=0x7f07005d}
at android.content.res.Resources.loadDrawable(Resources.java:2068)
at android.content.res.TypedArray.getDrawable(TypedArray.java:602)
at android.widget.ImageView.<init>(ImageView.java:129)
at android.support.v7.widget.AppCompatImageView.<init>(AppCompatImageView.java:72)
at android.support.v7.widget.AppCompatImageView.<init>(AppCompatImageView.java:68)
at android.support.v7.app.AppCompatViewInflater.createImageView(AppCompatViewInflater.java:182)
at android.support.v7.app.AppCompatViewInflater.createView(AppCompatViewInflater.java:106)
at android.support.v7.app.AppCompatDelegateImpl.createView(AppCompatDelegateImpl.java:1266)
at android.support.v7.app.AppCompatDelegateImpl.onCreateView(AppCompatDelegateImpl.java:1316)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:684)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:758)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:758)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:758)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
at android.support.v7.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:469)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140)
at com.example.u.locationtracker.MainActivity.onCreate(MainActivity.java:39)
at android.app.Activity.performCreate(Activity.java:5231)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2157)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2243)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5019)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)
The problem seems to lie in this line:
setContentView(R.layout.activity_main);
Are you sure, the layout exists and doesn't have compile errors?
A full stacktrace would be more helpful
I am pretty sure there is no problem in my XML or manifest. The problem has to be in my code (because I had altered my code slightly and it stopped working). The app crashes before it even begins. The error I got is:
java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.trainer.braintrainer/com.trainer.braintrainer.MainActivity}:
java.lang.NullPointerException: Attempt to invoke virtual method 'void
android.widget.Button.setText(java.lang.CharSequence)' on a null
object reference
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual
method 'void android.widget.Button.setText(java.lang.CharSequence)' on
a null object reference
at
com.trainer.braintrainer.MainActivity.generateQuestion(MainActivity.java:60)
at
com.trainer.braintrainer.MainActivity.onCreate(MainActivity.java:101)
at android.app.Activity.performCreate(Activity.java:6237)
at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 06-16
08:01:16.547 24091-24091/com.trainer.braintrainer I/Process: Sending
signal. PID: 24091 SIG: 9
Below is my Main java code:
package com.trainer.braintrainer;
import android.os.CountDownTimer;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import org.w3c.dom.Text;
import java.util.ArrayList;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
ArrayList<Integer> answers=new ArrayList<Integer>();
Random rand = new Random();
int locationOfCorrectAnswer;
Button startButton;
Button button0;
Button button1;
Button button2;
Button button3;
int score=0;
int numberOfQuestions=0;
TextView answerMessage;
String message;
TextView scoreText;
TextView sumTextView;
TextView timerText;
public void generateQuestion(){
int a=rand.nextInt(21);
int b=rand.nextInt(21);
sumTextView.setText(Integer.toString(a) + " + " + Integer.toString(b));
locationOfCorrectAnswer=rand.nextInt(4);
answers.clear();
int inCorrectAns;
for (int i=0;i<=3;i++){
if (i==locationOfCorrectAnswer){
answers.add(a+b);
}else{
inCorrectAns=rand.nextInt(50);
while (inCorrectAns==a+b){
inCorrectAns=rand.nextInt(50);
}
answers.add(inCorrectAns);
}
}
button0.setText(Integer.toString(answers.get(0)));
button1.setText(Integer.toString(answers.get(1)));
button2.setText(Integer.toString(answers.get(2)));
button3.setText(Integer.toString(answers.get(3)));
}
public void startButton(View view){
startButton.setVisibility(View.INVISIBLE);
}
public void answerFunction(View view){
int tappedLocation= (int)view.getTag();
if (tappedLocation==locationOfCorrectAnswer){
message="Correct!";
score++;
}else{
message="Wrong!";
}
answerMessage.setText(message);
scoreText.setText(Integer.toString(score) + "/" + Integer.toString(numberOfQuestions));
numberOfQuestions++;
generateQuestion();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startButton=(Button)findViewById(R.id.button5);
answerMessage=(TextView)findViewById(R.id.messageView);
sumTextView=(TextView)findViewById(R.id.sumTextView);
scoreText=(TextView)findViewById(R.id.scoreText);
timerText=(TextView)findViewById(R.id.timerText);
generateQuestion();
new CountDownTimer(30100,1000){
#Override
public void onTick(long millisUntilFinished) {
int seconds=(int) millisUntilFinished/1000;
timerText.setText(Integer.toString(seconds)+"s");
}
#Override
public void onFinish() {
answerMessage.setText("Done");
}
}.start();
button0=(Button)findViewById(R.id.ans1);
button1=(Button)findViewById(R.id.ans2);
button2=(Button)findViewById(R.id.ans3);
button3=(Button)findViewById(R.id.ans4);
}
}
You are calling the method generateQuestion(); before assigning value to the buttons: button1, button2 etc. When you do setText on these buttons, it throws a null object reference error. what you can do is:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startButton=(Button)findViewById(R.id.button5);
answerMessage=(TextView)findViewById(R.id.messageView);
sumTextView=(TextView)findViewById(R.id.sumTextView);
scoreText=(TextView)findViewById(R.id.scoreText);
timerText=(TextView)findViewById(R.id.timerText);
button0=(Button)findViewById(R.id.ans1);
button1=(Button)findViewById(R.id.ans2);
button2=(Button)findViewById(R.id.ans3);
button3=(Button)findViewById(R.id.ans4);
generateQuestion();
new CountDownTimer(30100,1000){
#Override
public void onTick(long millisUntilFinished) {
int seconds=(int) millisUntilFinished/1000;
timerText.setText(Integer.toString(seconds)+"s");
}
#Override
public void onFinish() {
answerMessage.setText("Done");
}
}.start();
}
}
That is assign the respective views to the button before calling the generateQuestion()
Errors and Chat Activity Dialog looks like this.
04-09 09:03:23.509 2722-2722/com.pz.mediatonmessanger E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.pz.mediatonmessanger, PID: 2722
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.pz.mediatonmessanger/com.pz.mediatonmessanger.ChatDialogActivity}: java.lang.InstantiationException: class com.pz.mediatonmessanger.ChatDialogActivity has no zero argument constructor
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2209)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.InstantiationException: class com.pz.mediatonmessanger.ChatDialogActivity has no zero argument constructor
at java.lang.Class.newInstance(Class.java:1563)
at android.app.Instrumentation.newActivity(Instrumentation.java:1065)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2199)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NoSuchMethodException: <init> []
at java.lang.Class.getConstructor(Class.java:531)
at java.lang.Class.getDeclaredConstructor(Class.java:510)
at java.lang.Class.newInstance(Class.java:1561)
at android.app.Instrumentation.newActivity(Instrumentation.java:1065)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2199)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Code
package com.pz.mediatonmessanger;
import android.app.ProgressDialog;
import android.content.Intent;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ListView;
import com.pz.mediatonmessanger.Adapter.ChatDialogsAdapter;
import com.quickblox.auth.QBAuth;
import com.quickblox.auth.session.BaseService;
import com.quickblox.auth.session.QBSession;
import com.quickblox.chat.QBChatService;
import com.quickblox.chat.QBRestChatService;
import com.quickblox.chat.model.QBChatDialog;
import com.quickblox.core.QBEntityCallback;
import com.quickblox.core.exception.BaseServiceException;
import com.quickblox.core.exception.QBResponseException;
import com.quickblox.core.request.QBRequestBuilder;
import com.quickblox.core.request.QBRequestGetBuilder;
import com.quickblox.users.model.QBUser;
import java.util.ArrayList;
public class ChatDialogActivity extends AppCompatActivity {
FloatingActionButton floatingActionButton;
ListView lstChatDialogs;
public ChatDialogActivity(FloatingActionButton floatingActionButton) {
this.floatingActionButton = floatingActionButton;
}
public ChatDialogActivity(ListView lstChatDialogs) {
this.lstChatDialogs = lstChatDialogs;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat_dialog);
createSessionForChat();
lstChatDialogs = (ListView)findViewById(R.id.lstChatDialogs);
loadChatDialogs();
floatingActionButton = (FloatingActionButton) findViewById(R.id.chatdialog_adduser);
floatingActionButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(ChatDialogActivity.this, ListUsersActivity.class );
startActivity(intent);
}
});
}
private void loadChatDialogs() {
QBRequestGetBuilder requestBuilder = new QBRequestGetBuilder();
requestBuilder.setLimit(100);
QBRestChatService.getChatDialogs(null,requestBuilder).performAsync(new QBEntityCallback<ArrayList<QBChatDialog>>() {
#Override
public void onSuccess(ArrayList<QBChatDialog> qbChatDialogs, Bundle bundle) {
//Kod
ChatDialogsAdapter adapter = new ChatDialogsAdapter(getBaseContext(),qbChatDialogs);
lstChatDialogs.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
#Override
public void onError(QBResponseException e) {
Log.e("Błąd",e.getMessage());
}
});
}
private void createSessionForChat() {
final ProgressDialog mDialog = new ProgressDialog(ChatDialogActivity.this);
mDialog.setMessage("Ładowanie...");
mDialog.setCanceledOnTouchOutside(false);
mDialog.show();
String user,password;
user = getIntent().getStringExtra("user");
password = getIntent().getStringExtra("password");
final QBUser qbUser = new QBUser(user,password);
QBAuth.createSession(qbUser).performAsync(new QBEntityCallback<QBSession>() {
#Override
public void onSuccess(QBSession qbSession, Bundle bundle) {
qbUser.setId(qbSession.getUserId());
try {
qbUser.setPassword(BaseService.getBaseService().getToken());
} catch (BaseServiceException e) {
e.printStackTrace();
}
QBChatService.getInstance().login(qbUser, new QBEntityCallback() {
#Override
public void onSuccess(Object o, Bundle bundle) {
mDialog.dismiss();
}
#Override
public void onError(QBResponseException e) {
Log.e("Błąd",""+e.getMessage());
}
});
}
#Override
public void onError(QBResponseException e) {
}
});
}
}
Activities don't have a constructor in Android, you can't create them as you do with other classes. They are instantiated by the system, all you need to do is to start them with context.startActivity(intent).
Remove all the constructors from this Activity and get a reference to the views with findViewById and you should be fine
This is the error message which shows up when I run the apk on my virtual device.
05-03 13:00:03.652 2354-2354/de.hochrad.hochradapp I/art﹕ Not late-enabling -Xcheck:jni (already on)
05-03 13:00:05.966 2354-2354/de.hochrad.hochradapp D/AndroidRuntime﹕ Shutting down VM
05-03 13:00:05.970 2354-2354/de.hochrad.hochradapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: de.hochrad.hochradapp, PID: 2354
java.lang.RuntimeException: Unable to start activity ComponentInfo{de.hochrad.hochradapp/de.hochrad.hochradapp.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
at android.widget.Toast.<init>(Toast.java:101)
at android.widget.Toast.makeText(Toast.java:250)
at de.hochrad.hochradapp.MainActivity.onCreate(MainActivity.java:26)
at android.app.Activity.performCreate(Activity.java:5937)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
05-03 13:00:08.238 2354-2354/de.hochrad.hochradapp I/Process﹕ Sending signal. PID: 2354 SIG: 9
Somehow it cannot find the required Resources.
I hope you can help me!!!
Thx for all answers!!!
package de.hochrad.hochradapp;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity {
ArrayAdapter<String> klassen_adapter;
Vertretungsplan vertretungsplan;
Spinner klassen;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toast.makeText(null, "Laden...", Toast.LENGTH_SHORT).show();
klassen_adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
klassen = (Spinner) findViewById(R.id.klassenspinner);
Thread downloadThread = new Thread() {
public void run() {
vertretungsplan = new Vertretungsplan("1");
runOnUiThread(new Runnable() {
#Override
public void run() {
if (vertretungsplan.Ex != null) {
klassen_adapter.add("Fehler!");
} else {
klassen_adapter.add("Wähle deine Klasse!");
for (Klassenvertretung s : vertretungsplan.Klassen) {
klassen_adapter.add(s.Bezeichnung);
}
}
}
});
}
};
downloadThread.start();
klassen.setAdapter(klassen_adapter);
klassen.setSelection(0);
klassen.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(parent.getContext(),
"Deine Auswahl ist:" + parent.getItemAtPosition(position).toString(), Toast.LENGTH_SHORT).show();
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
package de.hochrad.hochradapp;
import java.util.ArrayList;
import java.util.List;
public class Klassenvertretung {
public String Bezeichnung;
public List<Vertretung> Vertretungen = new ArrayList<Vertretung>();
public void Hinzufügen(Vertretung neuesElement) {
Vertretungen.add(neuesElement);
}
}
package de.hochrad.hochradapp;
public class Vertretung {
public String Klasse;
public String Stunde;
public String Art;
public String Fach;
public String Raum;
public String stattFach;
public String stattRaum;
public String Informationen;
}
package de.hochrad.hochradapp;
import org.jsoup.Connection;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class Vertretungsplan {
public Vertretungsplan(String woche) {
Woche = woche;
Einlesen(woche);
}
public String Woche;
public Exception Ex;
public List<Klassenvertretung> Klassen = new ArrayList<Klassenvertretung>();
private void Hinzufügen(Klassenvertretung neuesElement) {
Klassen.add(neuesElement);
}
private void Einlesen(String woche) {
try {
for (int webseite = 1; webseite < 10000; webseite++) {
Klassenvertretung klassenvertretung = new Klassenvertretung();
String teilseite = "0000";
if (webseite < 10)
teilseite = teilseite + "0";
teilseite = teilseite + webseite;
Connection connection = Jsoup
.connect("www.gymnasium-hochrad.de/Vertretungsplan/Vertretungsplan_Internet/"
+ woche + "/w/w" + teilseite + ".htm");
Document doc = connection.get();
Element h2 = doc.select("h2").get(0);
klassenvertretung.Bezeichnung = h2.text();
Element table = doc.select("table").get(1);
Element[] elemente = table.select("tr").toArray(new Element[0]);
for (int i = 1; i < elemente.length; i++) {
Element[] tds = elemente[i].select("td").toArray(
new Element[0]);
Vertretung vertretung = new Vertretung();
vertretung.Klasse = tds[0].text();
vertretung.Stunde = tds[1].text();
vertretung.Art = tds[2].text();
vertretung.Fach = tds[3].text();
vertretung.Raum = tds[4].text();
vertretung.stattFach = tds[5].text();
vertretung.stattRaum = tds[6].text();
vertretung.Informationen = tds[7].text();
klassenvertretung.Hinzufügen(vertretung);
}
Hinzufügen(klassenvertretung);
}
} catch (IOException io) {
if (Klassen.size() == 0) {
Ex = io;
}
} finally {
}
}
}
okay here is my code. I am form germany and so lots of Names are german (i hope thats not a problem.
Maybe it helps.
I guess the error must be in the main activity in one of the toasts. But dont hesitate to look at the other lines.
A/c to logcat error your are getting null reference error. try to update this line
Toast.makeText(parent.getContext(),
"Deine Auswahl ist:" + parent.getItemAtPosition(position).toString(), Toast.LENGTH_SHORT).show();
with the following code
Toast.makeText(MainActivity.this,
"Deine Auswahl ist:" + parent.getItemAtPosition(position).toString(), Toast.LENGTH_SHORT).show();
You have not initialised your adapter namely "klassen_adapter" in your main activity. It's null and invoking any method on it will be null pointer exception