有人可以帮我查一下我的代码有什么问题吗？我有4个spinner，其值已插入SQLite。现在我想将项目检索到另一个位于Update.java但得到java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
我已检查过每一步，但仍无法解决问题。
Update.java
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<String> list = new ArrayList<String>();
String project11 = c;
list.add(project11);
for(String s:arr){
if(!list.contains(s)){
list.add(s);
}
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(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<String> list = new ArrayList<String>();
String project22 = d;
list.add(project22);
for(String s:arr){
if(!list.contains(s)){
list.add(s);
}
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(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<String> list = new ArrayList<String>();
String project33 = e;
list.add(project33);
for(String s:arr){
if(!list.contains(s)){
list.add(s);
}
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(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<String> list = new ArrayList<String>();
String project44 = f;
list.add(project44);
for(String s:arr){
if(!list.contains(s)){
list.add(s);
}
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(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();
}
错误LogCat
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)
我有一个活动有一个微调器，下面的代码对我来说很好。
public void addWeather(String a) {
weather3 = (Spinner) findViewById(R.id.spinner5);
String[] arr = new String[]{"Sunny","Cloudy","Rainy","Thunderstorm"};
List<String> list = new ArrayList<String>();
String weather = a;
list.add(weather);
for(String s:arr){
if(!list.contains(s)){
list.add(s);
}
}
ArrayAdapter<String> adapter = new ArrayAdapter<String>(UpdatePage.this, android.R.layout.simple_spinner_dropdown_item, list);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
weather3.setAdapter(adapter);
}
答案 0 :(得分：2)
class address(ModelForm):
state = forms.ModelChoiceField(queryset = STATES.objects.all())
CITY = forms.ModelChoiceField(queryset = CITIES.objects.all())
class Meta:
model = REGIONS
fields = ('state', 'CITY',)
*方法之一中的参数为addProject。正如您在null的代码段中看到的那样：
ArrayAdapter.createViewFromResource ...检查T item = getItem(position);
if (item instanceof CharSequence) {
text.setText((CharSequence)item);
} else {
text.setText(item.toString());
}
，如果T不是instanceof Charsequence或CharSequence为空，则返回false。由于您的适配器属于T类型，因此我们可以排除第一种情况。因此，集合中的一个String为null。