DBAdapter.java：
public DBAdapter open() throws SQLException {
mDBHelper = new DBHelper(mctx,DATABASE_NAME,null,DATABASE_VERSION);
mDB = mDBHelper.getWritableDatabase();
return this;
}
public synchronized void close() {
mDBHelper.close();
}
public long insertRecord(String firstname, String middlename,
String lastname) {
ContentValues cv = new ContentValues();
cv.put(KEY_FIRSTNAME, firstname);
cv.put(KEY_MIDDLENAME, middlename);
cv.put(KEY_LASTNAME, lastname);
return mDB.insert(DATABASE_TABLE, null, cv);
}
public int deleteAll(){
return mDB.delete(DATABASE_TABLE, null, null);
}
public String getName() {
String column[] = new String[] { KEY_FIRSTNAME, KEY_MIDDLENAME,
KEY_LASTNAME };
Cursor c = mDB.query(DATABASE_TABLE, column, null, null, null, null,
null);
String name = "";
int iFirst = c.getColumnIndex(KEY_FIRSTNAME);
int iMiddle = c.getColumnIndex(KEY_MIDDLENAME);
int iLast = c.getColumnIndex(KEY_LASTNAME);
for (c.moveToFirst(); !c.isAfterLast(); c.moveToLast()) {
name = name + c.getString(iFirst) + "\t" + c.getString(iMiddle)
+ "\t" + c.getString(iLast) + "\t";
}
c.close();
return name;
}
Profile_database_view.java：
db = new DBAdapter(Profile_Database_View.this);
db.open();
full_name.setText(db.getName());
MainActivity.java：
dbadapter = new DBAdapter(MainActivity.this);
dbadapter.open();
dbadapter.insertRecord(first_name, middle_name, last_name);
dbadapter.close();
}
Logcat：
12-04 12:10:21.273: I/ActivityManager(60): Starting: Intent { cmp=com.example.display_from_database/.Profile_Database_View } from pid 364
12-04 12:10:21.802: D/dalvikvm(364): GC_EXTERNAL_ALLOC freed 704K, 56% free 2693K/6023K, external 2032K/2137K, paused 193ms
12-04 12:10:22.392: D/dalvikvm(364): GC_FOR_MALLOC freed 971K, 61% free 2656K/6727K, external 2379K/2971K, paused 118ms
12-04 12:10:22.853: D/dalvikvm(364): GC_CONCURRENT freed 793K, 60% free 2697K/6727K, external 2379K/2971K, paused 14ms+18ms
12-04 12:10:23.232: D/dalvikvm(364): GC_CONCURRENT freed 837K, 60% free 2703K/6727K, external 2379K/2971K, paused 26ms+7ms
12-04 12:10:23.482: D/dalvikvm(364): GC_CONCURRENT freed 854K, 60% free 2699K/6727K, external 2379K/2971K, paused 10ms+10ms
12-04 12:10:23.714: D/dalvikvm(364): GC_CONCURRENT freed 842K, 60% free 2706K/6727K, external 2379K/2971K, paused 9ms+7ms
12-04 12:10:23.952: D/dalvikvm(364): GC_CONCURRENT freed 838K, 60% free 2711K/6727K, external 2379K/2971K, paused 11ms+7ms
12-04 12:10:24.192: D/dalvikvm(364): GC_CONCURRENT freed 823K, 60% free 2739K/6727K, external 2379K/2971K, paused 10ms+9ms
12-04 12:10:24.432: D/dalvikvm(364): GC_CONCURRENT freed 852K, 60% free 2737K/6727K, external 2379K/2971K, paused 13ms+9ms
12-04 12:10:24.662: D/dalvikvm(364): GC_CONCURRENT freed 867K, 60% free 2725K/6727K, external 2379K/2971K, paused 10ms+7ms
12-04 12:10:24.912: D/dalvikvm(364): GC_CONCURRENT freed 857K, 60% free 2729K/6727K, external 2379K/2971K, paused 13ms+6ms
12-04 12:10:25.122: D/dalvikvm(364): GC_CONCURRENT freed 836K, 60% free 2752K/6727K, external 2379K/2971K, paused 8ms+8ms
12-04 12:10:25.352: D/dalvikvm(364): GC_CONCURRENT freed 875K, 60% free 2737K/6727K, external 2379K/2971K, paused 8ms+7ms
12-04 12:10:25.483: D/dalvikvm(364): GC_FOR_MALLOC freed 914K, 61% free 2670K/6727K, external 2379K/2971K, paused 108ms
12-04 12:10:25.702: D/dalvikvm(364): GC_CONCURRENT freed 731K, 59% free 2765K/6727K, external 2379K/2971K, paused 8ms+9ms
12-04 12:10:25.932: D/dalvikvm(364): GC_CONCURRENT freed 852K, 59% free 2781K/6727K, external 2379K/2971K, paused 11ms+7ms
12-04 12:10:26.163: D/dalvikvm(364): GC_CONCURRENT freed 859K, 59% free 2785K/6727K, external 2379K/2971K, paused 9ms+7ms
我能够将数据插入到数据库中，但在检索数据时会进入此状态 无限循环和我的应用程序变成一个空白的黑屏。有人遇到过这个吗？
帮助我们。这种情况一直发生在我身上，谷歌搜索说我正在做 使用CPU的一些密集过程，但它就像检索数据库一样简单。
答案 0 :(得分：2)
啊，是的，把两个答案放在一起 - 你的错误就是你的条件是达到c.isAfterLast()，但是你把它增加到c.moveToLast()，它永远不会在最后一步之后。因此，无论是更改条件还是将递增步骤更改为c.moveToNext()，您都可以。
祝你好运！
答案 1 :(得分：1)
你的for循环有问题
for（c.moveToFirst（）;！c.isAfterLast（）; c.moveToLast（））
c.moveToLast（）做了什么吗？
答案 2 :(得分：0)
你的循环是可疑的，如果你想通过迭代游标，总是使用do while。 e.g
if(cursor != null && cursor.moveToFirst()){
do{
// You code for reading from cursor
}while(cursor.moveToNext());
}
这将为你完成这项工作。
答案 3 :(得分：0)
SQLiteDatabase db = mDbHelper.getReadableDatabase();
// Define a projection that specifies which columns from the database
// you will actually use after this query.
String[] projection = {
COLUMN_ID,
KEY_FIRSTNAME,
KEY_MIDDLENAME,
KEY_LASTNAME
};
Cursor c = db.query(
TABLE_NAME, // The table to query
projection, // The columns to return
selection, // The columns for the WHERE clause
selectionArgs, // The values for the WHERE clause
null, // don't group the rows
null, // don't filter by row groups
null // The sort order
);
尝试这一点......在选择中，如果你需要，选择的参数会实现你的条件
答案 4 :(得分：0)
在for循环中将您的上一个条件c.moveToLast()更改为c.moveToNext()
试试如下：
public String getName() {
String column[] = new String[] { KEY_FIRSTNAME, KEY_MIDDLENAME,
KEY_LASTNAME };
Cursor c = mDB.query(DATABASE_TABLE, column, null, null, null, null,
null);
String name = "";
for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext())
{
int iFirst = c.getColumnIndex(KEY_FIRSTNAME);
int iMiddle = c.getColumnIndex(KEY_MIDDLENAME);
int iLast = c.getColumnIndex(KEY_LASTNAME);
name = name + c.getString(iFirst) + "\t" + c.getString(iMiddle)
+ "\t" + c.getString(iLast) + "\t";
}
c.close();
return name;
}