title: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
body: <p>Can someone help me to check what's wrong with my code ? I have 4 <code>spinner</code>and their value has been inserted to <code>SQLite</code>.Now I want to retrieve the item out to another spinner which is in <code>Update.java</code> but get <code>java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference</code></p>
  
  <p>I have checked each single step but still cannot figure out the problem.</p>
  
  <p><strong>Update.java</strong></p>
  
  <pre><code> public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          dbHelper = new MyDatabaseHelper(this);
          setContentView(R.layout.updatepage);
          final String name = getIntent().getExtras().getString("name1");
          final String date=getIntent().getExtras().getString("date1");
          final String ID = getIntent().getExtras().getString("ID");
          RetrievePage(name,date,ID);
      }
  
       public void addProject1(String c)
          {
              project1=(Spinner)findViewById(R.id.spinner8);
              String[] arr = new String[]{"Pro-XXX-XXX","TRN-XXX-XXX","SRV-XXX-XXX","PRO-REE-BERGARDING","PRO-SKM-SSS","PRO-SKM-DI","PRO-SKM-PACKING","PRO-SIE-AVAGO_S110",
              "PRO-SIE-BIOCON","PRO-BCM-T13/T17","TRIN-IN_HOUSE","TRIN-EXTERNAL","SRIV-SIE-LEMONGRASS","SRV-PW-SIMOCODE","SRV-REE-SIMOCODE","PRO-SKM-D5","PRO-SKM-DRIOU","PRO-BKI-DESMET",
              "PRO-BKI-INFINEON","PRO-INH-ANDROID","PRO-BCM-S120","PRO-GAW-OP"};
              List&lt;String&gt; list = new ArrayList&lt;String&gt;();
              String project11 = c;
              list.add(project11);
              for(String s:arr){
                  if(!list.contains(s)){
                      list.add(s);
                  }
              }
              ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(UpdatePage.this, android.R.layout.simple_spinner_dropdown_item, list);
              adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
              project1.setAdapter(adapter);
          }
  
          public void addProject2(String d)
          {
              project2=(Spinner)findViewById(R.id.spinner9);
              String[] arr = new String[]{"Pro-XXX-XXX","TRN-XXX-XXX","SRV-XXX-XXX","PRO-REE-BERGARDING","PRO-SKM-SSS","PRO-SKM-DI","PRO-SKM-PACKING","PRO-SIE-AVAGO_S110",
                      "PRO-SIE-BIOCON","PRO-BCM-T13/T17","TRIN-IN_HOUSE","TRIN-EXTERNAL","SRIV-SIE-LEMONGRASS","SRV-PW-SIMOCODE","SRV-REE-SIMOCODE","PRO-SKM-D5","PRO-SKM-DRIOU","PRO-BKI-DESMET",
                      "PRO-BKI-INFINEON","PRO-INH-ANDROID","PRO-BCM-S120","PRO-GAW-OP"};
              List&lt;String&gt; list = new ArrayList&lt;String&gt;();
              String project22 = d;
              list.add(project22);
              for(String s:arr){
                  if(!list.contains(s)){
                      list.add(s);
                  }
              }
              ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(UpdatePage.this, android.R.layout.simple_spinner_dropdown_item, list);
              adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
              project2.setAdapter(adapter);
          }
  
          public void addProject3(String e)
          {
              project3=(Spinner)findViewById(R.id.spinner13);
              String[] arr = new String[]{"Pro-XXX-XXX","TRN-XXX-XXX","SRV-XXX-XXX","PRO-REE-BERGARDING","PRO-SKM-SSS","PRO-SKM-DI","PRO-SKM-PACKING","PRO-SIE-AVAGO_S110",
                      "PRO-SIE-BIOCON","PRO-BCM-T13/T17","TRIN-IN_HOUSE","TRIN-EXTERNAL","SRIV-SIE-LEMONGRASS","SRV-PW-SIMOCODE","SRV-REE-SIMOCODE","PRO-SKM-D5","PRO-SKM-DRIOU","PRO-BKI-DESMET",
                      "PRO-BKI-INFINEON","PRO-INH-ANDROID","PRO-BCM-S120","PRO-GAW-OP"};
              List&lt;String&gt; list = new ArrayList&lt;String&gt;();
              String project33 = e;
              list.add(project33);
              for(String s:arr){
                  if(!list.contains(s)){
                      list.add(s);
                  }
              }
              ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(UpdatePage.this, android.R.layout.simple_spinner_dropdown_item, list);
              adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
              project3.setAdapter(adapter);
          }
  
          public void addProject4(String f)
          {
              project4=(Spinner)findViewById(R.id.spinner14);
              String[] arr = new String[]{"Pro-XXX-XXX","TRN-XXX-XXX","SRV-XXX-XXX","PRO-REE-BERGARDING","PRO-SKM-SSS","PRO-SKM-DI","PRO-SKM-PACKING","PRO-SIE-AVAGO_S110",
                      "PRO-SIE-BIOCON","PRO-BCM-T13/T17","TRIN-IN_HOUSE","TRIN-EXTERNAL","SRIV-SIE-LEMONGRASS","SRV-PW-SIMOCODE","SRV-REE-SIMOCODE","PRO-SKM-D5","PRO-SKM-DRIOU","PRO-BKI-DESMET",
                      "PRO-BKI-INFINEON","PRO-INH-ANDROID","PRO-BCM-S120","PRO-GAW-OP"};
              List&lt;String&gt; list = new ArrayList&lt;String&gt;();
              String project44 = f;
              list.add(project44);
              for(String s:arr){
                  if(!list.contains(s)){
                      list.add(s);
                  }
              }
              ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(UpdatePage.this, android.R.layout.simple_spinner_dropdown_item, list);
              adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
              project4.setAdapter(adapter);
          }
  
  
          public void RetrievePage(String name,String date, String id) {
              final String name2 = name;
              final String date2=date;
              final String id2 = id;
              final EditText name3 = (EditText) findViewById(R.id.editText9);
              final EditText date3 = (EditText) findViewById(R.id.editText12);
  
              final EditText per1=(EditText) findViewById(R.id.editText20);
              final EditText per2=(EditText) findViewById(R.id.editText24);
              final EditText per3=(EditText) findViewById(R.id.editText28);
              final EditText per4=(EditText) findViewById(R.id.editText32);
  
              database = dbHelper.getWritableDatabase();
              c = database.rawQuery("SELECT i.Weather, i.Status,w.Subcontractors, w.NumberOfPerson, w.NumberOfHours, wd.Project, wd.WorkDescription, wd.Per, wd.TimeIn, wd.TimeOut FROM Information i LEFT JOIN WorkForce w ON w.TInfo_id = i._id LEFT JOIN WorkDetails wd ON wd.Twf_id=w._id WHERE i.Name = ? AND i._id= ? ",
                      new String[]{String.valueOf(name2),String.valueOf(id2)}, null);
  
                  if (c != null) {
                      while (c.moveToNext()) {
  
                          Details WD = new Details();
  
  
                     String
       Weather = c.getString(c.getColumnIndexOrThrow(MyDatabaseHelper.Weather));
  
                             String Project11=c.getString(c.getColumnIndexOrThrow(MyDatabaseHelper.Project));
                             String Project22=c.getString(c.getColumnIndexOrThrow(MyDatabaseHelper.Project));
                             String 
  
  Project33=c.getString(c.getColumnIndexOrThrow(MyDatabaseHelper.Project));
                          String Project44=c.getString(c.getColumnIndexOrThrow(MyDatabaseHelper.Project));
                          String Per1=c.getString(c.getColumnIndexOrThrow(MyDatabaseHelper.Per));
                          String Per2=c.getString(c.getColumnIndexOrThrow(MyDatabaseHelper.Per));
                          String Per3=c.getString(c.getColumnIndexOrThrow(MyDatabaseHelper.Per));
                          String Per4=c.getString(c.getColumnIndexOrThrow(MyDatabaseHelper.Per));
                          addProject1(Project11);
                          addProject2(Project22);
                          addProject3(Project33);
                         addProject4(Project44);
                         addWeather(Weather);
  
                          WD.setProject(Project11);
                          WD.setProject(Project22);
                          WD.setProject(Project33);
                          WD.setProject(Project44);
                          WD.setPer(Per1);
                          WD.setPer(Per2);
                          WD.setPer(Per3);
                          WD.setPer(Per4);
                          per1.setText(Per1);
                          per2.setText(Per2);
                          per3.setText(Per3);
                          per4.setText(Per4);
  
                      }
  
                  }
                  c.close();
  
  
              }
  </code></pre>
  
  <p><strong>Error LogCat</strong></p>
  
  <pre><code>  Process: com.example.project.project, PID: 2364
      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.AbsSpinner.onMeasure(AbsSpinner.java:194)
              at android.widget.Spinner.onMeasure(Spinner.java:580)
              at android.support.v7.widget.AppCompatSpinner.onMeasure(AppCompatSpinner.java:410)
              at android.view.View.measure(View.java:18788)
              at android.view.ViewGroup.measureChild(ViewGroup.java:5922)
              at android.view.ViewGroup.measureChildren(ViewGroup.java:5899)
              at android.widget.AbsoluteLayout.onMeasure(AbsoluteLayout.java:66)
  </code></pre>
  
  <p>I have one activity which has one spinner and the code below works fine to me.</p>
  
  <pre><code>public void addWeather(String a) {
      weather3 = (Spinner) findViewById(R.id.spinner5);
      String[] arr = new String[]{"Sunny","Cloudy","Rainy","Thunderstorm"};
      List&lt;String&gt; list = new ArrayList&lt;String&gt;();
      String weather = a;
      list.add(weather);
      for(String s:arr){
          if(!list.contains(s)){
              list.add(s);
          }
      }
      ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(UpdatePage.this, android.R.layout.simple_spinner_dropdown_item, list);
      adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
      weather3.setAdapter(adapter);
  }
  </code></pre>