I am still learning android studio and i am attempting to make an application that will generate timetables (for schools preferably). I have recently added an activity that will be entered when "new timetable" is selected. The error that I get when I run the code on my galaxy s5 (running android 6.0) is as followed:
05-21 20:49:05.813 2771-2771/com.example.ben.timetablegen E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.ben.timetablegen, PID: 2771
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:401)
at android.widget.ArrayAdapter.getView(ArrayAdapter.java:369)
at android.widget.Spinner.measureContentWidth(Spinner.java:917)
at android.widget.Spinner.onMeasure(Spinner.java:636)
at android.support.v7.widget.AppCompatSpinner.onMeasure(AppCompatSpinner.java:407)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:747)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:747)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:610)
at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:677)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:747)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:747)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:629)
at android.view.View.measure(View.java:20151)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6328)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:194)
at com.android.internal.policy.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:3158)
at android.view.View.measure(View.java:20151)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2594)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1549)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1841)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1437)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7397)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:920)
at android.view.Choreographer.doCallbacks(Choreographer.java:695)
at android.view.Choreographer.doFrame(Choreographer.java:631)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:906)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7224)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
The two Java activity are as follows: The main activity:
package com.example.ben.timetablegen;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;
public class HomeActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
String tables[] = getTableList();
// Selection of the spinner
Spinner spinner = (Spinner) findViewById(R.id.dropdown1);
// Application of the Array to the Spinner
ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, tables);
spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); // The drop down view
spinner.setAdapter(spinnerArrayAdapter);
int orientation = getScreenOrientation();
if (orientation == 1){
final TextView sessionHead = (TextView) findViewById(R.id.sessionHead);
final TextView monHead = (TextView) findViewById(R.id.monHead);
final TextView tueHead = (TextView) findViewById(R.id.tueHead);
final TextView wedHead = (TextView) findViewById(R.id.wedHead);
final TextView thuHead = (TextView) findViewById(R.id.thuHead);
final TextView friHead = (TextView) findViewById(R.id.friHead);
sessionHead.setText(R.string.tableHead1Short);
monHead.setText(R.string.tableHead2Short);
tueHead.setText(R.string.tableHead3Short);
wedHead.setText(R.string.tableHead4Short);
thuHead.setText(R.string.tableHead5Short);
friHead.setText(R.string.tableHead6Short);
}
if (orientation == 2){
final TextView sessionHead = (TextView) findViewById(R.id.sessionHead);
final TextView monHead = (TextView) findViewById(R.id.monHead);
final TextView tueHead = (TextView) findViewById(R.id.tueHead);
final TextView wedHead = (TextView) findViewById(R.id.wedHead);
final TextView thuHead = (TextView) findViewById(R.id.thuHead);
final TextView friHead = (TextView) findViewById(R.id.friHead);
sessionHead.setText(R.string.tableHead1);
monHead.setText(R.string.tableHead2);
tueHead.setText(R.string.tableHead3);
wedHead.setText(R.string.tableHead4);
thuHead.setText(R.string.tableHead5);
friHead.setText(R.string.tableHead6);
}
if (orientation == 0) {
final TextView sessionHead = (TextView) findViewById(R.id.sessionHead);
final TextView monHead = (TextView) findViewById(R.id.monHead);
final TextView tueHead = (TextView) findViewById(R.id.tueHead);
final TextView wedHead = (TextView) findViewById(R.id.wedHead);
final TextView thuHead = (TextView) findViewById(R.id.thuHead);
final TextView friHead = (TextView) findViewById(R.id.friHead);
sessionHead.setText(R.string.error);
monHead.setText(R.string.error);
tueHead.setText(R.string.error);
wedHead.setText(R.string.error);
thuHead.setText(R.string.error);
friHead.setText(R.string.error);
}
}
public int getScreenOrientation() {
if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT){
return 1;
}
if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE){
return 2;
}
return 0;
}
public void newTimetable(){
Intent newTimetableActivity = new Intent(this,newTimetable.class);
newTimetableActivity.putExtra("timeTables",getTableList());
}
@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_home, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public String[] getTableList() {
SharedPreferences prefs = getSharedPreferences("tableList",MODE_PRIVATE);
String R[] = {"Select a table",prefs.getString("tables", null),"New table"};
return R;
}
}
And the "New Timetable" activity:
package com.example.ben.timetablegen;
import android.app.Activity;
import android.os.Bundle;
public class newTimetable extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.new_timetable);
}
}
I have added the new timetable to the manifest. Thanks in advance.
*I have trawled through other answers and because they are never specific to my circumstances, they seldom answer my problems