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Bir sınıf programı uygulaması yapmaya çalışıyorum. Ancak, bir sorunla karşılaştım ve nasıl çözeceğimi bilmiyorum.java.lang.NullPointerException: Sanal yöntem 'boolean java.util.Vector.add (java.lang.Object)' öğesini null bir nesne başvurusu üzerinde çalıştırmayı deneyin
Hem Google hem de StackOverflow'ta etrafa baktım, olabildiğince fazla bilgi buldum. Ancak, işe yaramadı. Şimdi umarım kodumla ilgili yardım alabilirim.
Android geliştirmede göreceli olarak deneyimsizim. Ve kodum çirkin. Kodumun kalitesini artırabilirseniz size minnettar olacağım.
Şimdiden teşekkürler.
MainActivity.java
package com.example.lee.myapplication;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.util.Vector;
import butterknife.Bind;
import butterknife.ButterKnife;
import butterknife.OnClick;
public class MainActivity extends AppCompatActivity {
private MyDatabaseHelper dbHelper;
private Vector<Course_lee> courseList;
private TextView tv_mainActivity;
@Bind(R.id.back)
Button back;
@Bind(R.id.week)
TextView week;
@Bind(R.id.set)
Button set;
@Bind(R.id.mon)
TextView mon;
@Bind(R.id.tue)
TextView tue;
@Bind(R.id.wed)
TextView wed;
@Bind(R.id.thur)
TextView thur;
@Bind(R.id.fri)
TextView fri;
@Bind(R.id.sta)
TextView sta;
@Bind(R.id.sun)
TextView sun;
@Bind(R.id.textView1_1)
TextView textView11;
@Bind(R.id.textView1_2)
TextView textView12;
@Bind(R.id.textView1_3)
TextView textView13;
@Bind(R.id.textView1_4)
TextView textView14;
@Bind(R.id.textView1_5)
TextView textView15;
@Bind(R.id.textView1_6)
TextView textView16;
@Bind(R.id.textView1_7)
TextView textView17;
@Bind(R.id.textView2_1)
TextView textView21;
@Bind(R.id.textView2_2)
TextView textView22;
@Bind(R.id.textView2_3)
TextView textView23;
@Bind(R.id.textView2_4)
TextView textView24;
@Bind(R.id.textView2_5)
TextView textView25;
@Bind(R.id.textView2_6)
TextView textView26;
@Bind(R.id.textView2_7)
TextView textView27;
@Bind(R.id.textView3_1)
TextView textView31;
@Bind(R.id.textView3_2)
TextView textView32;
@Bind(R.id.textView3_3)
TextView textView33;
@Bind(R.id.textView3_4)
TextView textView34;
@Bind(R.id.textView3_5)
TextView textView35;
@Bind(R.id.textView3_6)
TextView textView36;
@Bind(R.id.textView3_7)
TextView textView37;
@Bind(R.id.textView4_1)
TextView textView41;
@Bind(R.id.textView4_2)
TextView textView42;
@Bind(R.id.textView4_3)
TextView textView43;
@Bind(R.id.textView4_4)
TextView textView44;
@Bind(R.id.textView4_5)
TextView textView45;
@Bind(R.id.textView4_6)
TextView textView46;
@Bind(R.id.textView4_7)
TextView textView47;
@Bind(R.id.textView5_1)
TextView textView51;
@Bind(R.id.textView5_2)
TextView textView52;
@Bind(R.id.textView5_3)
TextView textView53;
@Bind(R.id.textView5_4)
TextView textView54;
@Bind(R.id.textView5_5)
TextView textView55;
@Bind(R.id.textView5_6)
TextView textView56;
@Bind(R.id.textView5_7)
TextView textView57;
@Bind(R.id.textView6_1)
TextView textView61;
@Bind(R.id.textView6_2)
TextView textView62;
@Bind(R.id.textView6_3)
TextView textView63;
@Bind(R.id.textView6_4)
TextView textView64;
@Bind(R.id.textView6_5)
TextView textView65;
@Bind(R.id.textView6_6)
TextView textView66;
@Bind(R.id.textView6_7)
TextView textView67;
@Bind(R.id.textView7_1)
TextView textView71;
@Bind(R.id.textView7_2)
TextView textView72;
@Bind(R.id.textView7_3)
TextView textView73;
@Bind(R.id.textView7_4)
TextView textView74;
@Bind(R.id.textView7_5)
TextView textView75;
@Bind(R.id.textView7_6)
TextView textView76;
@Bind(R.id.textView7_7)
TextView textView77;
@Bind(R.id.textView8_1)
TextView textView81;
@Bind(R.id.textView8_2)
TextView textView82;
@Bind(R.id.textView8_3)
TextView textView83;
@Bind(R.id.textView8_4)
TextView textView84;
@Bind(R.id.textView8_5)
TextView textView85;
@Bind(R.id.textView8_6)
TextView textView86;
@Bind(R.id.textView8_7)
TextView textView87;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_lee);
ButterKnife.bind(this);
dbHelper = new MyDatabaseHelper(this, "CourseStore.db", null, 1);
SQLiteDatabase db =dbHelper.getWritableDatabase();
Cursor cursor = db.rawQuery("select * from course", null);
first_init(db,cursor);
init(cursor);
cursor.close();
}
private void first_init(SQLiteDatabase db,Cursor cursor) {
if (!cursor.moveToFirst()) {
Log.e("tag", String.valueOf(new Course_lee(R.id.textView1_1).getId()));
courseList.add(new Course_lee(R.id.textView1_1));
courseList.add(new Course_lee(R.id.textView1_2));
courseList.add(new Course_lee(R.id.textView1_3));
courseList.add(new Course_lee(R.id.textView1_4));
courseList.add(new Course_lee(R.id.textView1_5));
courseList.add(new Course_lee(R.id.textView1_6));
courseList.add(new Course_lee(R.id.textView1_7));
courseList.add(new Course_lee(R.id.textView2_1));
courseList.add(new Course_lee(R.id.textView2_2));
courseList.add(new Course_lee(R.id.textView2_3));
courseList.add(new Course_lee(R.id.textView2_4));
courseList.add(new Course_lee(R.id.textView2_5));
courseList.add(new Course_lee(R.id.textView2_6));
courseList.add(new Course_lee(R.id.textView2_7));
courseList.add(new Course_lee(R.id.textView3_1));
courseList.add(new Course_lee(R.id.textView3_2));
courseList.add(new Course_lee(R.id.textView3_3));
courseList.add(new Course_lee(R.id.textView3_4));
courseList.add(new Course_lee(R.id.textView3_5));
courseList.add(new Course_lee(R.id.textView3_6));
courseList.add(new Course_lee(R.id.textView3_7));
courseList.add(new Course_lee(R.id.textView4_1));
courseList.add(new Course_lee(R.id.textView4_2));
courseList.add(new Course_lee(R.id.textView4_3));
courseList.add(new Course_lee(R.id.textView4_4));
courseList.add(new Course_lee(R.id.textView4_5));
courseList.add(new Course_lee(R.id.textView4_6));
courseList.add(new Course_lee(R.id.textView4_7));
courseList.add(new Course_lee(R.id.textView5_1));
courseList.add(new Course_lee(R.id.textView5_2));
courseList.add(new Course_lee(R.id.textView5_3));
courseList.add(new Course_lee(R.id.textView5_4));
courseList.add(new Course_lee(R.id.textView5_5));
courseList.add(new Course_lee(R.id.textView5_6));
courseList.add(new Course_lee(R.id.textView5_7));
courseList.add(new Course_lee(R.id.textView6_1));
courseList.add(new Course_lee(R.id.textView6_2));
courseList.add(new Course_lee(R.id.textView6_3));
courseList.add(new Course_lee(R.id.textView6_4));
courseList.add(new Course_lee(R.id.textView6_5));
courseList.add(new Course_lee(R.id.textView6_6));
courseList.add(new Course_lee(R.id.textView6_7));
courseList.add(new Course_lee(R.id.textView7_1));
courseList.add(new Course_lee(R.id.textView7_2));
courseList.add(new Course_lee(R.id.textView7_3));
courseList.add(new Course_lee(R.id.textView7_4));
courseList.add(new Course_lee(R.id.textView7_5));
courseList.add(new Course_lee(R.id.textView7_6));
courseList.add(new Course_lee(R.id.textView7_7));
courseList.add(new Course_lee(R.id.textView8_1));
courseList.add(new Course_lee(R.id.textView8_2));
courseList.add(new Course_lee(R.id.textView8_3));
courseList.add(new Course_lee(R.id.textView8_4));
courseList.add(new Course_lee(R.id.textView8_5));
courseList.add(new Course_lee(R.id.textView8_6));
courseList.add(new Course_lee(R.id.textView8_7));
insertPrimaryTable(courseList,db);
}
}
private void insertPrimaryTable(Vector<Course_lee> courseList,SQLiteDatabase db) {
int id;
for (int i=0;i<courseList.size();i++){
id=courseList.elementAt(i).getId();
ContentValues values = new ContentValues();
values.put("id", id);
db.insert("course", null, values);
values.clear();
}
}
private void setWeek() {
}
private void init(Cursor cursor) {
//Cursor cursor = db.rawQuery("select * from course where day=? and time=?", new String[] {"1",""});
//Cursor cursor = db.rawQuery("select * from course",null);
if (cursor.moveToFirst()) {
do {
int id=cursor.getInt(cursor.getColumnIndex("id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
String num = cursor.getString(cursor.getColumnIndex("num"));
String teacher = cursor.getString(cursor.getColumnIndex("teacher"));
int jieshu =cursor.getInt(cursor.getColumnIndex("jieshu"));
int weekBegin =cursor.getInt(cursor.getColumnIndex("weekBegin"));
int weekEnd =cursor.getInt(cursor.getColumnIndex("weekEnd"));
int flag=cursor.getInt(cursor.getColumnIndex("flag"));
String time=cursor.getString(cursor.getColumnIndex("time"));
int day = cursor.getInt(cursor.getColumnIndex("day"));
tv_mainActivity= (TextView) findViewById(id);
tv_mainActivity.setText(name);
if (!courseList.isEmpty()){
for (int i=0;i<courseList.size();i++){
if(courseList.elementAt(i).getId()==id){
courseList.elementAt(i).setName(name);
courseList.elementAt(i).setClassNum(num);
courseList.elementAt(i).setTeacher(teacher);
courseList.elementAt(i).setJieshu(jieshu);
courseList.elementAt(i).setWeekBegin(weekBegin);
courseList.elementAt(i).setWeekEnd(weekEnd);
courseList.elementAt(i).setFlag(flag);
courseList.elementAt(i).setTime(time);
courseList.elementAt(i).setDay(day);
break;
}
}
}
} while (cursor.moveToNext());
}
}
void highlight(){
}
void updateTable(String name,String num){
}
private void enterDetail(Course_lee course) {
Intent intent = new Intent(MainActivity.this, DetailActivity.class);
intent.putExtra("course", course);
startActivity(intent);
}
@OnClick({R.id.back, R.id.set, R.id.textView1_1, R.id.textView1_2, R.id.textView1_3, R.id.textView1_4, R.id.textView1_5, R.id.textView1_6, R.id.textView1_7, R.id.textView2_1, R.id.textView2_2, R.id.textView2_3, R.id.textView2_4, R.id.textView2_5, R.id.textView2_6, R.id.textView2_7, R.id.textView3_1, R.id.textView3_2, R.id.textView3_3, R.id.textView3_4, R.id.textView3_5, R.id.textView3_6, R.id.textView3_7, R.id.textView4_1, R.id.textView4_2, R.id.textView4_3, R.id.textView4_4, R.id.textView4_5, R.id.textView4_6, R.id.textView4_7, R.id.textView5_1, R.id.textView5_2, R.id.textView5_3, R.id.textView5_4, R.id.textView5_5, R.id.textView5_6, R.id.textView5_7, R.id.textView6_1, R.id.textView6_2, R.id.textView6_3, R.id.textView6_4, R.id.textView6_5, R.id.textView6_6, R.id.textView6_7, R.id.textView7_1, R.id.textView7_2, R.id.textView7_3, R.id.textView7_4, R.id.textView7_5, R.id.textView7_6, R.id.textView7_7, R.id.textView8_1, R.id.textView8_2, R.id.textView8_3, R.id.textView8_4, R.id.textView8_5, R.id.textView8_6, R.id.textView8_7})
public void onClick(View view) {
Course_lee course;
switch (view.getId()) {
case R.id.back:
finish();
break;
case R.id.set:
break;
case R.id.textView1_1:
course=findCorrectCourse(R.id.textView1_1);
enterDetail(course);
break;
case R.id.textView1_2:
course=findCorrectCourse(R.id.textView1_2);
enterDetail(course);
break;
case R.id.textView1_3:
course=findCorrectCourse(R.id.textView1_3);
enterDetail(course);
break;
case R.id.textView1_4:
course=findCorrectCourse(R.id.textView1_4);
enterDetail(course);
break;
case R.id.textView1_5:
break;
case R.id.textView1_6:
break;
case R.id.textView1_7:
break;
case R.id.textView2_1:
break;
case R.id.textView2_2:
break;
case R.id.textView2_3:
break;
case R.id.textView2_4:
break;
case R.id.textView2_5:
break;
case R.id.textView2_6:
break;
case R.id.textView2_7:
break;
case R.id.textView3_1:
break;
case R.id.textView3_2:
break;
case R.id.textView3_3:
break;
case R.id.textView3_4:
break;
case R.id.textView3_5:
break;
case R.id.textView3_6:
break;
case R.id.textView3_7:
break;
case R.id.textView4_1:
break;
case R.id.textView4_2:
break;
case R.id.textView4_3:
break;
case R.id.textView4_4:
break;
case R.id.textView4_5:
break;
case R.id.textView4_6:
break;
case R.id.textView4_7:
break;
case R.id.textView5_1:
break;
case R.id.textView5_2:
break;
case R.id.textView5_3:
break;
case R.id.textView5_4:
break;
case R.id.textView5_5:
break;
case R.id.textView5_6:
break;
case R.id.textView5_7:
break;
case R.id.textView6_1:
break;
case R.id.textView6_2:
break;
case R.id.textView6_3:
break;
case R.id.textView6_4:
break;
case R.id.textView6_5:
break;
case R.id.textView6_6:
break;
case R.id.textView6_7:
break;
case R.id.textView7_1:
break;
case R.id.textView7_2:
break;
case R.id.textView7_3:
break;
case R.id.textView7_4:
break;
case R.id.textView7_5:
break;
case R.id.textView7_6:
break;
case R.id.textView7_7:
break;
case R.id.textView8_1:
break;
case R.id.textView8_2:
break;
case R.id.textView8_3:
break;
case R.id.textView8_4:
break;
case R.id.textView8_5:
break;
case R.id.textView8_6:
break;
case R.id.textView8_7:
break;
}
}
private Course_lee findCorrectCourse(int tv) {
Course_lee course;
for (int i=0;i<courseList.size();i++) {
if (courseList.elementAt(i).getId() == tv) {
course=courseList.elementAt(i);
return course;
}
}
return null;
}
}
Course_lee.java
package com.example.lee.myapplication;
import android.os.Parcel;
import android.os.Parcelable;
public class Course_lee implements Parcelable {
private int id;
private String name;
private String classNum;
private String teacher;
private int jieshu;
private int weekBegin;
private int weekEnd;
private int flag;
private String time;
private int day;
public Course_lee(int id, String name, String classNum, String teacher, int jieshu, int weekBegin, int weekEnd, int flag, String time, int day) {
this.id = id;
this.name = name;
this.classNum = classNum;
this.teacher = teacher;
this.jieshu = jieshu;
this.weekBegin = weekBegin;
this.weekEnd = weekEnd;
this.flag = flag;
this.time = time;
this.day = day;
}
public Course_lee(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getClassNum() {
return classNum;
}
public void setClassNum(String classNum) {
this.classNum = classNum;
}
public String getTeacher() {
return teacher;
}
public void setTeacher(String teacher) {
this.teacher = teacher;
}
public int getJieshu() {
return jieshu;
}
public void setJieshu(int jieshu) {
this.jieshu = jieshu;
}
public int getWeekBegin() {
return weekBegin;
}
public void setWeekBegin(int weekBegin) {
this.weekBegin = weekBegin;
}
public int getWeekEnd() {
return weekEnd;
}
public void setWeekEnd(int weekEnd) {
this.weekEnd = weekEnd;
}
public int getFlag() {
return flag;
}
public void setFlag(int flag) {
this.flag = flag;
}
public String getTime() {
return time;
}
public void setTime(String time) {
this.time = time;
}
public int getDay() {
return day;
}
public void setDay(int day) {
this.day = day;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(this.id);
dest.writeString(this.name);
dest.writeString(this.classNum);
dest.writeString(this.teacher);
dest.writeInt(this.jieshu);
dest.writeInt(this.weekBegin);
dest.writeInt(this.weekEnd);
dest.writeInt(this.flag);
dest.writeString(this.time);
dest.writeInt(this.day);
}
protected Course_lee(Parcel in) {
this.id = in.readInt();
this.name = in.readString();
this.classNum = in.readString();
this.teacher = in.readString();
this.jieshu = in.readInt();
this.weekBegin = in.readInt();
this.weekEnd = in.readInt();
this.flag = in.readInt();
this.time = in.readString();
this.day = in.readInt();
}
public static final Creator<Course_lee> CREATOR = new Creator<Course_lee>() {
@Override
public Course_lee createFromParcel(Parcel source) {
return new Course_lee(source);
}
@Override
public Course_lee[] newArray(int size) {
return new Course_lee[size];
}
};
}
MyDatabaseHelper.java
package com.example.lee.myapplication;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;
public class MyDatabaseHelper extends SQLiteOpenHelper {
public static final String CREATE_COURSE="create table course("
+"id integer primary key, "
+ "name text, "
+ "num text, "
+ "teacher text, "
+ "jieshu integer,"
+ "weekBegin integer,"
+ "weekEnd integer,"
+ "flag integer,"
+ "time text,"
+ "day integer)";
public MyDatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_COURSE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
Logcat
03-25 11:36:34.647 10013-10013/com.example.lee.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.lee.myapplication, PID: 10013
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.lee.myapplication/com.example.lee.myapplication.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.util.Vector.add(java.lang.Object)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.util.Vector.add(java.lang.Object)' on a null object reference
at com.example.lee.myapplication.MainActivity.first_init(MainActivity.java:181)
at com.example.lee.myapplication.MainActivity.onCreate(MainActivity.java:171)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
önce
onCreateBu ekle ama 'first_init' işlevi' de courselist' başlatmak. – theoneLeeO zaman nerede olacak? Gönderdiğiniz kod, – 0xDEADC0DE
'u baştan başlatamaz. Yolunuzu düzeltmeye çalışıyorum. – theoneLee