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POjava.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() WHY?
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When i ran the first activity..there was no error But when i tried running the second activity ERROR "java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()" Activity with no looper problem <pre><code>package com.example.androidnotizer; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.os.Handler; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; import android.widget.Toast; public class LoginActivity extends Activity { public static final String URL="jdbc:mysql://10.0.2.2/notizer"; public static final String USER="root"; public static final String PASSWORD="apple"; public static final String Driver_Class="com.mysql.jdbc.Driver"; public static final int RED=-65536; Handler handler = new Handler(); Thread background; String uid,pass; int count=0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_login); TextView tv = (TextView)findViewById(R.id.textView4); tv.setText(""); Button login = (Button) findViewById(R.id.button1); login.setOnClickListener(new OnClickListener(){ @Override public void onClick(View arg0) { EditText et1 = (EditText)findViewById(R.id.editText1); EditText et2 = (EditText)findViewById(R.id.editText2); uid=et1.getText().toString(); pass=et2.getText().toString(); TextView tv = (TextView)findViewById(R.id.textView4); tv.setText(""); count=0; doLogin(); } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.login,menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.action_signup: Intent i = new Intent(LoginActivity.this,SignUpActivity.class); startActivity(i); } return true; } public void doLogin(){ background = new Thread(new Runnable(){ @Override public void run(){ try{ Class.forName(Driver_Class); Connection con = DriverManager.getConnection(URL, USER, PASSWORD); Statement st = con.createStatement(); ResultSet rs =st.executeQuery("select * from login where user_id='"+ uid +"' and password='"+ pass +"'"); while(rs.next()){ count++; } }catch(Exception e){ e.printStackTrace(); } Runnable r=new Runnable() { @Override public void run() { if(count==0){ Toast.makeText(getApplicationContext(), "Unsuccessful Login", Toast.LENGTH_SHORT).show(); TextView tv = (TextView)findViewById(R.id.textView4); tv.setText("Wrong user_id or password"); tv.setTextColor(RED); } else{ Intent i = new Intent(LoginActivity.this,NoticeActivity.class); startActivity(i); } } }; handler.post(r); } } ); background.start(); } } </code></pre> Activity with looper problem <pre><code>package com.example.androidnotizer; import java.sql.Connection; import java.sql.DriverManager; import java.sql.Statement; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.os.Handler; import android.util.SparseBooleanArray; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android.widget.ArrayAdapter; import android.widget.Button; import android.widget.ListView; import android.widget.Toast; public class StudentSignUpActivity extends Activity implements OnClickListener { public static final String URL="jdbc:mysql://10.0.2.2/notizer"; public static final String USER="root"; public static final String PASSWORD="apple"; public static final String Driver_Class="com.mysql.jdbc.Driver"; Handler handler = new Handler(); Thread background; Button button,combi; ListView listView; ArrayAdapter<String> adapter; String fname,lname,mname,gender,mobile,designation,passPapers,roll,department,year; int count=0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_student_sign_up); Intent intent =getIntent(); fname = intent.getStringExtra("fname"); mname = intent.getStringExtra("mname"); lname = intent.getStringExtra("lname"); gender = intent.getStringExtra("gender"); mobile = intent.getStringExtra("mobile"); designation = intent.getStringExtra("designation"); roll = intent.getStringExtra("roll"); department = intent.getStringExtra("department"); year = intent.getStringExtra("year"); findViewById(); String[] sports = getResources().getStringArray(R.array.papers_array); adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_multiple_choice, sports); listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE); listView.setAdapter(adapter); button.setOnClickListener(this); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.student_sign_up, menu); return true; } private void findViewById() { listView = (ListView) findViewById(R.id.dept_listView1); button = (Button) findViewById(R.id.done); } @Override public void onClick(View arg0) { SparseBooleanArray checked = listView.getCheckedItemPositions(); passPapers=""; for (int i = 0; i < checked.size(); i++) { int position = checked.keyAt(i); if (checked.valueAt(i)) if((i+1) < checked.size()){ passPapers=passPapers+String.valueOf(adapter.getItem(position))+","; } else{ passPapers=passPapers+String.valueOf(adapter.getItem(position)); } } doSignUp(); } public void doSignUp(){ Toast.makeText(getApplicationContext(),"Inside doSignUp()",Toast.LENGTH_LONG).show(); background = new Thread(new Runnable(){ @Override public void run(){ try{ Toast.makeText(getApplicationContext(),"Inside try",Toast.LENGTH_LONG).show(); Class.forName(Driver_Class); Connection con = DriverManager.getConnection(URL, USER, PASSWORD); Statement st = con.createStatement(); //st.executeUpdate("insert into student(roll_no,fname,mname,lname,gender,mobile_no,department,year,pass_papers,desigantion) values('"+ roll +"','"+ fname +"','"+ mname +"','"+ lname +"','"+ gender +"','"+ mobile +"','"+ department +"','"+ year +"','"+ passPapers +"','"+ designation +"')"); st.executeUpdate("insert into login(user_id,password) values('"+ roll +"','"+ roll +"')"); count=1; }catch(Exception e){ count=0; e.printStackTrace(); Toast.makeText(getApplicationContext(),e.toString(),Toast.LENGTH_LONG).show(); } Runnable r=new Runnable() { @Override public void run() { if(count==1){ Toast.makeText(getApplicationContext(), "Successful Sign Up\nYour user_id : " + roll + "\nand password : " + roll, Toast.LENGTH_LONG).show(); Intent i = new Intent(StudentSignUpActivity.this,NoticeActivity.class); startActivity(i); } else{ Toast.makeText(getApplicationContext(), "Unsuccessful Sign Up\nTry Again", Toast.LENGTH_LONG).show(); Intent i = new Intent(StudentSignUpActivity.this,SignUpActivity.class); startActivity(i); } } }; handler.post(r); } } ); background.start(); } } </code></pre> LogCat <pre><code>12-10 06:49:48.823: E/AndroidRuntime(5021): FATAL EXCEPTION: Thread-344 12-10 06:49:48.823: E/AndroidRuntime(5021): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() 12-10 06:49:48.823: E/AndroidRuntime(5021): at android.os.Handler.<init>(Handler.java:197) 12-10 06:49:48.823: E/AndroidRuntime(5021): at android.os.Handler.<init>(Handler.java:111) 12-10 06:49:48.823: E/AndroidRuntime(5021): at android.widget.Toast$TN.<init>(Toast.java:324) 12-10 06:49:48.823: E/AndroidRuntime(5021): at android.widget.Toast.<init>(Toast.java:91) 12-10 06:49:48.823: E/AndroidRuntime(5021): at android.widget.Toast.makeText(Toast.java:238) 12-10 06:49:48.823: E/AndroidRuntime(5021): at com.example.androidnotizer.StudentSignUpActivity$1.run(StudentSignUpActivity.java:104) 12-10 06:49:48.823: E/AndroidRuntime(5021): at java.lang.Thread.run(Thread.java:841) </code></pre>
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java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare() WHY?
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