SQLite in Android How to update a specific row

First make a ContentValues object :

ContentValues cv = new ContentValues();
cv.put("Field1","Bob"); //These Fields should be your String values of actual column names
cv.put("Field2","19");
cv.put("Field2","Male");

Then use the update method, it should work now:

myDB.update(TableName, cv, "_id = ?", new String[]{id});

Simple way:

String strSQL = "UPDATE myTable SET Column1 = someValue WHERE columnId = "+ someValue;

myDataBase.execSQL(strSQL);

1. I personally prefere .update for its convenience. But execsql will work same.
2. You are right with your guess that the problem is your content values. You should create a ContentValue Object and put the values for your database row there.

This code should fix your example:

 ContentValues data=new ContentValues();
 data.put("Field1","bob");
 data.put("Field2",19);
 data.put("Field3","male");
 DB.update(Tablename, data, "_id=" + id, null);

At first create a ContentValues object :

ContentValues cv = new ContentValues();
cv.put("Field1","Bob");
cv.put("Field2","19");

Then use the update method. Note, the third argument is the where clause. The "?" is a placeholder. It will be replaced with the fourth argument (id)

myDB.update(MY_TABLE_NAME, cv, "_id = ?", new String[]{id});

This is the cleanest solution to update a specific row.