Getting "Variable might not initialized error"-CodePudding

I am creating function for Sqlite database and getting "variable might not initialized" error. I am trying to store sqlite data in string array.


public String[] gettitle()
  {
          String title[];
          String s = "select Title from User_DB;";
          SQLiteDatabase db = getReadableDatabase();
          Cursor cursor = db.rawQuery(s,null);
          int a = 0;
          while(cursor.moveToNext())
          {

              title[a] = cursor.getString(0);
              a  ;
          }
          return title;
  }

it says title[] is not initialized but I dont understand why. I clearly initialized it.

CodePudding user response：

You declare title. Allowed C language style is String title[]. In java one keeps the type expression together: String[] title;
```
   String[] title;
```
This variable is uninitialized, reserves a memory slot for an array object, but the memory is not filled, initialized; it contains garbage. At its first usage of title the compiler issues an error.

In contrast class fields are initialized automatically by a default: here null, but for other types 0, false, 0.0 and so on.
Initialize the variable: give it an initial value.

For arrays that means set an array object. Arrays are fixed length, cannot grow, and thus:
```
 String[] title;
 title = new String[10];
```
Or shorter:
```
 String[] title = new String[10];
```
Like fields also array elements are initialized with defaults, null.

Note you initialized a: int a = 0;.
Now you can use the array object through the variable:
```
       title[a] = cursor.getString(0);
```
This was the point where the compiler saw the usage of a variable that still did not have a value.

So the code becomes:

public String[] loadTitles() {
    String[] titles = new String[100];
    String sql = "select Title from User_DB";
    SQLiteDatabase db = getReadableDatabase();
    int a = 0;
    try (Cursor cursor = db.rawQuery(sql, null)) {
        while (a < titles.length && cursor.moveToNext()) {
            titles[a] = cursor.getString(0);
            a  ;
        }
    } // Calls cursor.close();
    return Arrays.copyOf(titles, a);
}

Array.copyOf(array, newLength) make copy of the original array with as new length the number of read titles.

I have added the (weird) try-with-resources syntax which ensures that cursor is closed, even on exception or return happening inside the block.