-1
그래서 학생을위한 간단한 클래스 관리자를 만들고 있는데,이 문제를 파악할 수 없습니다. 주 활동에는 수업을 추가하는 버튼이 있습니다.이 버튼을 누르면 학생 활동 추가로 이동하는 학생 추가 버튼이있는 수업 활동 추가로 이동합니다. 학생을 구할 때 클래스 활동 추가로 돌아가 학생 명을 명부 목록보기에 추가하면됩니다. 그러나 어떤 이유로 클래스를 저장할 때 주 활동으로 돌아올 때 nullPointerException이 발생합니다. 아무도 아이디어가 있다면 정말 도움을 주시면 감사하겠습니다. 클래스 추가 활동 여기NullPointerException 학생 클래스 구성 도우미
public class MainActivity extends Activity {
ListView classList;
Button addClass;
ArrayAdapter<String> adapterClass;
ArrayList<Class> currClasses = new ArrayList<Class>();
ArrayList<String> currClassNames = new ArrayList<String>();
ClassesSingleton myClasses;
int REQUEST_CODE_ADD = 318;
int REQUEST_CODE_EDIT = 319;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
classList = (ListView) findViewById(R.id.classList);
final Context context = this;
adapterClass = new ArrayAdapter<String>(this, R.layout.single_list_item, R.id.label, currClassNames);
classList.setAdapter(adapterClass);
addClass = (Button) this.findViewById(R.id.addClass);
classList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView <?> arg0, View view, int position, long id){
Intent intent = new Intent(MainActivity.this, ShowClass.class);
startActivityForResult(intent, REQUEST_CODE_EDIT);
}
});
addClass.setOnClickListener(new OnClickListener() {
public void onClick(View arg0){
Intent intent = new Intent(MainActivity.this, AddClass.class);
startActivityForResult(intent, REQUEST_CODE_ADD);
}
});
}
protected void onActivityResult(int requestCode, int resultCode, Intent data){
super.onActivityResult(requestCode, resultCode, data);
if(resultCode == RESULT_OK && requestCode == REQUEST_CODE_ADD){
Class newClass = new Class();
if(data.hasExtra("className")){
newClass.setName(data.getExtras().getString("name"));
}
if(data.hasExtra("number")){
newClass.setNumber(data.getExtras().getInt("number"));
}
if(data.hasExtra("students")){
ArrayList<Student> s = data.getExtras().getParcelableArrayList("students");
newClass.setStudents(s);
}
if(data.hasExtra("names")){
ArrayList<String> sn = data.getExtras().getStringArrayList("names");
newClass.setStudentNames(sn);
}
myClasses = ClassesSingleton.getInstance();
updateClassList(newClass, newClass.getName());
myClasses.setClassArray(currClasses);
myClasses.setClassNames(currClassNames);
}
//else if(resultCode == RESULT_OK && requestCode == REQUEST_CODE_EDIT){
//}
}
public void updateClassList(Class n, String s){
adapterClass = null;
currClasses.add(n);
currClassNames.add(s);
adapterClass = new ArrayAdapter<String>(this, R.layout.single_list_item, R.id.label, currClassNames);
classList.setAdapter(adapterClass);
adapterClass.notifyDataSetChanged();
}
}
것 :
: 여기public class AddStudent extends Activity{
EditText studentName, studentId;
Button saveStudent, cancelStudent;
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.new_student);
studentName = (EditText) findViewById(R.id.newStudentName);
studentId = (EditText) findViewById(R.id.newStudentId);
saveStudent = (Button) findViewById(R.id.confirmStudentAdd);
cancelStudent = (Button) findViewById(R.id.cancelStudent);
saveStudent.setOnClickListener(new OnClickListener() {
public void onClick(View arg0){
Intent data = new Intent();
int idData = 0;
if(studentName.getText().toString().matches("") != true && studentId.getText().toString().matches("") != true){
String nameData = studentName.getText().toString();
String idStr = studentId.getText().toString();
boolean intTrue = true;
try{
idData = Integer.parseInt(idStr);
}catch(NumberFormatException e){
Toast.makeText(AddStudent.this, "Please be sure to enter a numeric value in the ID field.", Toast.LENGTH_LONG).show();
intTrue = false;
}
if(intTrue){
data.putExtra("name", nameData);
data.putExtra("id", idData);
setResult(RESULT_OK, data);
finish();
}
}
else{
Toast.makeText(AddStudent.this, "Don't leave your student name or ID field blank!", Toast.LENGTH_LONG).show();
}
}
});
}
}
public class AddClass extends Activity{
Button addStudent, saveClass, cancelClass;
EditText className, classNumber;
ListView studentList;
ArrayAdapter<String> adapterStudent;
ArrayList<Student> currStudents = new ArrayList<Student>();
ArrayList<String> studNames = new ArrayList<String>();
int REQUEST_CODE_ADDSTU = 317;
int REQUEST_CODE_EDSTU = 316;
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
Intent intent = getIntent();
setContentView(R.layout.new_class);
addStudent = (Button) findViewById(R.id.addStudent);
saveClass = (Button) findViewById(R.id.confirmClassAdd);
cancelClass = (Button) findViewById(R.id.cancelClass);
className = (EditText) findViewById(R.id.newClassName);
classNumber = (EditText) findViewById(R.id.newClassNumber);
studentList = (ListView) findViewById(R.id.newStudentList);
adapterStudent = new ArrayAdapter<String>(this, R.layout.single_list_item, R.id.label, studNames);
studentList.setAdapter(adapterStudent);
studentList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView <?> arg0, View view, int position, long id){
Intent intent2 = new Intent(AddClass.this, EditStudent.class);
startActivityForResult(intent2, REQUEST_CODE_EDSTU);
}
});
addStudent.setOnClickListener(new OnClickListener() {
public void onClick(View arg0){
Intent intent2 = new Intent(AddClass.this, AddStudent.class);
startActivityForResult(intent2, REQUEST_CODE_ADDSTU);
}
});
saveClass.setOnClickListener(new OnClickListener() {
public void onClick(View arg0){
Intent data = new Intent();
int numData = 0;
if(className.getText().toString().matches("") != true && classNumber.getText().toString().matches("") != true && currStudents.isEmpty() != true && studNames.isEmpty() != true){
String nameData = className.getText().toString();
String numStr = classNumber.getText().toString();
ArrayList<Student> students = currStudents;
ArrayList<String> studentNames = studNames;
boolean intTrue = true;
try{
numData = Integer.parseInt(numStr);
}catch(NumberFormatException e){
Toast.makeText(AddClass.this, "Please be sure to enter a numberic value in the number field.", Toast.LENGTH_LONG).show();
intTrue = false;
}
if(intTrue){
data.putExtra("className", nameData);
data.putExtra("number", numData);
data.putStringArrayListExtra("names", studentNames);
data.putParcelableArrayListExtra("students", students);
setResult(RESULT_OK, data);
finish();
}
}
else{
Toast.makeText(AddClass.this, "Don't leave your class name, number field, or student roster blank!", Toast.LENGTH_LONG).show();
}
}
});
}
//onActivityResult callback
protected void onActivityResult(int requestCode, int resultCode, Intent data){
super.onActivityResult(requestCode, resultCode, data);
if(resultCode == RESULT_OK && requestCode == REQUEST_CODE_ADDSTU){
Student newStudent = new Student();
if(data.hasExtra("name")){
newStudent.setName(data.getExtras().getString("name"));
}
if(data.hasExtra("id")){
newStudent.setId(data.getExtras().getInt("id"));
}
updateStudentList(newStudent, newStudent.getName());
}
}
public void updateStudentList(Student s, String n){
adapterStudent = null;
currStudents.add(s);
studNames.add(n);
adapterStudent = new ArrayAdapter<String>(this, R.layout.single_list_item, R.id.label, studNames);
studentList.setAdapter(adapterStudent);
adapterStudent.notifyDataSetChanged();
}
}
여기에 주요 활동입니다
FATAL EXCEPTION: main
Process: com.example.congelassign2, PID: 1664
java.lang.NullPointerException
at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
at android.widget.AbsListView.obtainView(AbsListView.java:2263)
at android.widget.ListView.makeAndAddView(ListView.java:1790)
at android.widget.ListView.fillDown(ListView.java:691)
at android.widget.ListView.fillFromTop(ListView.java:752)
at android.widget.ListView.layoutChildren(ListView.java:1616)
at android.widget.AbsListView.onLayout(AbsListView.java:2091)
at android.view.View.layout(View.java:14785)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
at android.view.View.layout(View.java:14785)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
at android.view.View.layout(View.java:14785)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at com.android.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:374)
at android.view.View.layout(View.java:14785)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
at android.view.View.layout(View.java:14785)
at android.view.ViewGroup.layout(ViewGroup.java:4631)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1985)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1742)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5582)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
at android.view.Choreographer.doCallbacks(Choreographer.java:562)
at android.view.Choreographer.doFrame(Choreographer.java:532)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4998)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
at dalvik.system.NativeStart.main(Native Method)
내 친구를 디버그하십시오. – NewUser
어떤 메소드가 예외를 throw합니다 .Exception 스택 트레이스가 명확하지 않습니다. – Kick
어떤 라인에서 에러가 발생 했습니까 ?? – Piyush