java - Android - 更改表格列现在会使程序崩溃。 java.lang.NumberFormatException : Invalid int: "T" 异常

Question

我正在更改我的数据库结构，因为我注意到有些事情的顺序不正确。这样做之后，它会弹出一条错误消息

02-10 19:42:06.562: E/AndroidRuntime(1215): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.project/com.example.project.MainActivity}: java.lang.NumberFormatException: Invalid int: "T"

“T”是我之前用于测试数据的名称，因此我推测这是数据库中已有的数据，现在随着列的变化而标记错误。

我想如果我在 onCreate() 的最开始删除数据库，那么它会清除数据库并插入新的测试数据并消除错误。但是我仍然得到完全相同的错误!

完整代码如下:

MainActivity.java

public class MainActivity extends Activity {

    Intent appIntent;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); 
        DB db = new DB(this);
        db.insertStudent("Matt", "male", 22, "password", "computing", "modules");
        List<tableStudents> outputList = db.getData();    
        for (tableStudents student: outputList) {
            // Log your results.
            Log.d("result_list", student.toString());
        }

    }

    public void goHomepage(View v)
    {
        Intent intent = new Intent(MainActivity.this, Homepage.class);
        startActivity(intent);
    }
    public void goAccount(View v)
    {
        Intent intent = new Intent(MainActivity.this, MyAccount.class);
        startActivity(intent);
    }   

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

DB.java

public class DB extends SQLiteOpenHelper {
public static final int db_version = 1;  
public static final String Table = "Students";  
public static final String Student_ID = "Student_ID";
public static final String Student_Name = "Student_Name";
public static final String Student_Password = "Student_Password";
public static final String Student_Gender = "gender";
public static final String Student_Age = "age";
public static final String Student_Course = "course";
public static final String Modules = "modules";
public DB(Context context) {
    super(context, tableColumns.Database, null, db_version);
}

@Override
public void onCreate(SQLiteDatabase db) {
    delete(db);
    //Create Table
    db.execSQL("CREATE TABLE " + Table + "(" + 
            Student_ID + " INTEGER PRIMARY KEY, " +
            Student_Name + " TEXT, " +
            Student_Password + " TEXT, " +
            Student_Gender + " TEXT, " +
            Student_Age + " INTEGER, " +
            Student_Course + " TEXT, " +
            Modules + " TEXT)");
    Log.d("DB", "DB Created");      
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS " + Table);
    onCreate(db);
}

public void delete(SQLiteDatabase db)
{
    db.delete(Table, null, null);       
}

public List<tableStudents> getData() {
    List<tableStudents> studentList = new ArrayList<tableStudents>();
    // Select All Query
    String selectQuery = "SELECT  * FROM " + Table;

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            tableStudents student = new tableStudents();
            student.name = cursor.getString(0);
            student.gender = cursor.getString(1);
            student.age = Integer.parseInt(cursor.getString(2));
            student.password = cursor.getString(3);
            student.course = cursor.getString(4);
            student.modules = cursor.getString(5);
            studentList.add(student);
        } while (cursor.moveToNext());
    }

    // return contact list
    return studentList;

}


public boolean insertStudent(String name, String gender, int age, String password, String course, String modules) {

    SQLiteDatabase db = getWritableDatabase();

    ContentValues contentValues = new ContentValues();
    contentValues.put(Student_Name, name);
    contentValues.put(Student_Password, password);
    contentValues.put(Student_Gender, gender);
    contentValues.put(Student_Age, age);        
    contentValues.put(Student_Course, course);
    contentValues.put(Modules, modules);
    db.insert(Table, null, contentValues);
    Log.d("DB", "Inserted Successfully");
    return true;
}

}

tableStudents.java

public class tableStudents {
     public String name, gender, password, course, modules;
        public int age;
    //Constructor
    public tableStudents()
    {

    }

     //constructor
    public tableStudents(String name, String gender, int age, String password, String course, String modules)
    {
        this.name = name;
        this.password = password;
        this.gender = gender;
        this.age = age;      
        this.course = course;
        this.modules = modules;
    }


    public static abstract class tableColumns implements BaseColumns
    {
        public static final String Student_ID= "Student_ID";
        public static final String Student_Name= "Student_Name";
        public static final String Student_Password = "Student_Password";
        public static final String Student_Gender = "gender";
        public static final String Student_Age = "age";
        public static final String Student_Course = "course";
        public static final String Modules = "modules";
        public static final String Database = "databasename";
        public static final String Table = "tablename";
    }


}

LogCat

02-10 19:56:42.132: D/DB(1741): Inserted Successfully
02-10 19:56:42.142: D/AndroidRuntime(1741): Shutting down VM
02-10 19:56:42.147: E/AndroidRuntime(1741): FATAL EXCEPTION: main
02-10 19:56:42.147: E/AndroidRuntime(1741): Process: com.example.project, PID: 1741
02-10 19:56:42.147: E/AndroidRuntime(1741): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.project/com.example.project.MainActivity}: java.lang.NumberFormatException: Invalid int: "T"
02-10 19:56:42.147: E/AndroidRuntime(1741):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at android.app.ActivityThread.access$800(ActivityThread.java:151)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at android.os.Handler.dispatchMessage(Handler.java:102)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at android.os.Looper.loop(Looper.java:135)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at android.app.ActivityThread.main(ActivityThread.java:5257)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at java.lang.reflect.Method.invoke(Native Method)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at java.lang.reflect.Method.invoke(Method.java:372)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
02-10 19:56:42.147: E/AndroidRuntime(1741): Caused by: java.lang.NumberFormatException: Invalid int: "T"
02-10 19:56:42.147: E/AndroidRuntime(1741):     at java.lang.Integer.invalidInt(Integer.java:138)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at java.lang.Integer.parse(Integer.java:410)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at java.lang.Integer.parseInt(Integer.java:367)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at java.lang.Integer.parseInt(Integer.java:334)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at com.example.project.DB.getData(DB.java:72)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at com.example.project.MainActivity.onCreate(MainActivity.java:31)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at android.app.Activity.performCreate(Activity.java:5990)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
02-10 19:56:42.147: E/AndroidRuntime(1741):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)

Answer 1

在 onCreate() 的开头试试这个:

deleteDatabase("your_db_name");