android检查表是否为空-androidcheckiftableisempty

4  

You nested the if statements in the wrong way. This way, assuming the rest is correct, should works:

您以错误的方式嵌套if语句。这样，假设其余部分是正确的，应该有效：

public boolean checkForTables(){
    boolean hasTables = false;
    db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery("SELECT * FROM " +TABLE_CONTACTS, null);

    if(cursor != null && cursor.getCount() > 0){
        hasTables=true;
        cursor.close();
    } 

    return hasTables;
}

BTW, performing a SELECT COUNT(*) should be more efficient:

顺便说一下，执行SELECT COUNT（*）应该更有效：

public boolean checkForTables(){

  db = this.getWritableDatabase();
  Cursor cursor = db.rawQuery("SELECT COUNT(*) FROM " +TABLE_CONTACTS, null);

  if(cursor != null){

    cursor.moveToFirst();

    int count = cursor.getInt(0);

    if(count > 0){
      return true;
    }

    cursor.close();
  } 

  return false;
}

1  

if condition is wrong, try this:

如果条件错误，试试这个：

public boolean checkForTables(){
    db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery("SELECT * FROM " +TABLE_CONTACTS, null);
    if(cursor != null && cursor.getCount() > 0){
        cursor.close();
        return true;
    } 
    return false;
}

0  

You have mistiped your brackets:

你错了你的括号：

if(cursor.getCount() == 0){
    hasTables=false;
if(cursor.getCount() > 0){
    hasTables=true;
}

cursor.close();
}

to this:

对此：

if(cursor.getCount() == 0){
    hasTables=false;
}
else if(cursor.getCount() > 0){
    hasTables=true;
}

cursor.close();

0  

You could try:

你可以尝试：

Cursor cursor = db.rawQuery(select count(*) from +TABLE_CONTACTS, null);
cursor.moveToFirst();
int count= cursor.getInt(0);

if(count == 0){
    hasTables=false;
}
else if(count > 0){
    hasTables=true;
}