这是一个简单的数据库应用程序，它将某些内容存储在表格中（按钮点击）并删除（按钮点击）。在设备（棒棒糖）上安装应用程序时，会弹出主要活动，但只要我在文本字段中输入一些文本并单击按钮将其保存到数据库，应用程序会冻结并在一段时间后强制关闭。如果我尝试再次运行应用程序，然后主活动无法启动，应用程序强制关闭。
这是主要活动，
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
EditText myinput;
TextView mytext;
MyDBHandler dbhandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myinput =(EditText) findViewById(R.id.myinput);
mytext =(TextView) findViewById(R.id.mytext);
dbhandler= new MyDBHandler(this, null, null, 1);
printDatabase();
}
//add product to database
public void addstuff(View view)
{
products product = new products(myinput.getText().toString());
dbhandler.addProduct(product);
printDatabase();
}
//delete items from database
public void deletestuff(View view)
{
String inputtext= myinput.getText().toString();
dbhandler.deleteProduct(inputtext);
printDatabase();
}
public void printDatabase()
{
String dbString= dbhandler.databaseToString();
mytext.setText(dbString);
myinput.setText("");
}
}
这是数据库处理程序类
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.Cursor;
import android.content.Context;
import android.content.ContentValues;
public class MyDBHandler extends SQLiteOpenHelper{
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "products.db";
public static final String TABLE_PRODUCTS = "products";
public static final String COLUMN_ID ="_id";
public static final String COLUMN_PRODUCTNAME ="productname";
public MyDBHandler(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context, DATABASE_NAME, factory, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String query= "CREATE TABLE " + TABLE_PRODUCTS + "(" +
COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT , " +
COLUMN_PRODUCTNAME + " TEXT " +
");";
db.execSQL(query);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS "+TABLE_PRODUCTS);
onCreate(db);
}
//add a new row to the database
public void addProduct(products product)
{
ContentValues values = new ContentValues();
values.put(COLUMN_PRODUCTNAME, product.get_productname());
SQLiteDatabase db= getWritableDatabase();
db.insert(TABLE_PRODUCTS, null, values);
db.close();
}
//delete product from the database
public void deleteProduct(String productname)
{
SQLiteDatabase db= getWritableDatabase();
db.execSQL("DELETE FROM "+ TABLE_PRODUCTS + " WHERE " + COLUMN_PRODUCTNAME + " =\"" + productname + "\";" );
}
//printing out the database as a string
public String databaseToString()
{
String dbString ="";
SQLiteDatabase db= getWritableDatabase();
String query = "SELECT * FROM "+ TABLE_PRODUCTS + " WHERE 1";
//CURSOR POINTS TO A LOCATION IN THE DATABASE RESULTS
Cursor c= db.rawQuery(query,null);
//go to 1st row in your results
c.moveToFirst();
while(!c.isAfterLast())
{
if(c.getString(c.getColumnIndex("productname"))!=null)
{
dbString += c.getString(c.getColumnIndex("productname"));
dbString += "\n";
}
}
db.close();
return dbString;
}
}
这是我用来设置和获取名字的产品类
public class products {
private int _id;
private String _productname;
public products()
{
}
public products(String productname) {
this._productname = productname;
}
public void set_id(int _id) {
this._id = _id;
}
public void set_productname(String _productname) {
this._productname = _productname;
}
public int get_id() {
return _id;
}
public String get_productname() {
return _productname;
}
}
App冻结，
08-19 00:46:24.567 24251-24251/com.example.vashisht.sqliteapp I/art﹕ Late-enabling -Xcheck:jni
08-19 00:46:24.567 24251-24251/com.example.vashisht.sqliteapp I/art﹕ VMHOOK: rlim_cur : 0 pid:24251
08-19 00:46:24.887 24251-24251/com.example.vashisht.sqliteapp D/Atlas﹕ Validating map...
08-19 00:46:24.937 24251-24300/com.example.vashisht.sqliteapp I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: TEST SBA LA.BF.1.1.1_RB1 AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.00.02.042.012 + c1105519 + c_apilogging ()
OpenGL ES Shader Compiler Version: E031.25.03.00
Build Date: 01/23/15 Fri
Local Branch:
Remote Branch: refs/tags/AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.00.02.042.012
Local Patches: NONE
Reconstruct Branch: NOTHING
08-19 00:46:25.077 24251-24251/com.example.vashisht.sqliteapp I/InputMethodManager﹕ [startInputInner] EditorInfo { packageName=com.example.vashisht.sqliteapp, inputType=0x20001, imeOptions=0x40000006, privateImeOptions=null }, windowGainingFocus=android.view.ViewRootImpl$W@1287b4e7, mServedView=android.support.v7.widget.AppCompatEditText{e909894 VFED..CL .F....I. 90,222-990,335 #7f0c004f app:id/myinput}, mServedInputConnectionWrapper=android.view.inputmethod.InputMethodManager$ControlledInputConnectionWrapper@18863f3d
08-19 00:46:31.627 24251-24261/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 7.228ms
08-19 00:46:34.287 24251-24266/com.example.vashisht.sqliteapp I/art﹕ Background sticky concurrent mark sweep GC freed 143(4KB) AllocSpace objects, 84(4MB) LOS objects, 8% free, 5MB/5MB, paused 5.643ms total 24.844ms
08-19 00:46:34.987 24251-24265/com.example.vashisht.sqliteapp I/art﹕ WaitForGcToComplete blocked for 9.670ms for cause HeapTrim
08-19 00:46:36.647 24251-24261/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 5.596ms
我杀了应用
08-19 00:49:09.147 1196-1196/? D/NetworkController﹕ [WifiActivity] Connectd: 3
08-19 00:49:09.177 963-1155/? E/WifiStateMachine﹕ handleMessage: E msg.what=131155
08-19 00:49:09.177 963-1155/? E/WifiStateMachine﹕ processMsg: ConnectedState
08-19 00:49:09.177 963-1155/? E/WifiStateMachine﹕ ConnectedState !CMD_RSSI_POLL 888 0 "unbreakable_13_90" 3c:1e:04:5b:2f:2d rssi=-40 f=2412 sc=60 link=150 tx=13.0, 0.0, 0.0 rx=12.5 bcn=0 [on:0 tx:0 rx:0 period:816] from screen [on:0 period:1111505026] gl hn u24 rssi=-35 ag=0 hr ticks 4,88,362 ls-=0 [56,56,60,60,65] brc=0 lrc=0
08-19 00:49:09.177 963-1155/? E/WifiStateMachine﹕ processMsg: L2ConnectedState
08-19 00:49:09.177 963-1155/? E/WifiStateMachine﹕ L2ConnectedState !CMD_RSSI_POLL 888 0 "unbreakable_13_90" 3c:1e:04:5b:2f:2d rssi=-40 f=2412 sc=60 link=150 tx=13.0, 0.0, 0.0 rx=12.5 bcn=0 [on:0 tx:0 rx:0 period:3] from screen [on:0 period:1111505029] gl hn u24 rssi=-35 ag=0 hr ticks 4,88,362 ls-=0 [56,56,60,60,65] brc=0 lrc=0
08-19 00:49:09.187 963-1155/? E/WifiStateMachine﹕ get link layer stats 0
08-19 00:49:09.187 963-1155/? W/WifiHW﹕ QCOM Debug wifi_send_command "IFNAME=wlan0 SIGNAL_POLL"
08-19 00:49:09.187 763-763/? D/wpa_supplicant﹕ wlan0: Control interface command 'SIGNAL_POLL'
08-19 00:49:09.197 763-763/? I/wpa_supplicant﹕ environment dirty rate=0 [6][0][0]
08-19 00:49:09.197 963-1155/? E/WifiStateMachine﹕ fetchRssiLinkSpeedAndFrequencyNative RSSI = -39 abnormalRssiCnt = 0 newLinkSpeed = 150
08-19 00:49:09.197 963-1155/? E/WifiStateMachine﹕ fetchRssiLinkSpeedAndFrequencyNative rssi=-39 linkspeed=150
08-19 00:49:09.197 963-1155/? E/WifiConfigStore﹕ updateConfiguration freq=2412 BSSID=3c:1e:04:5b:2f:2d RSSI=-39 "unbreakable_13_90"WPA_PSK
08-19 00:49:09.197 963-1155/? E/WifiStateMachine﹕ calculateWifiScore freq=2412 speed=150 score=60 highRSSI -> txbadrate=0.00 txgoodrate=9.52 txretriesrate=0.00 rxrate=9.23 userTriggerdPenalty0
08-19 00:49:09.197 963-1155/? E/WifiStateMachine﹕ good link -> stuck count =0
08-19 00:49:09.197 963-1155/? E/WifiStateMachine﹕ badRSSI count0 lowRSSI count0 --> score 60
08-19 00:49:09.197 963-1155/? E/WifiStateMachine﹕ isHighRSSI ---> score=65
08-19 00:49:09.207 963-1173/? D/WifiWatchdogStateMachine﹕ RSSI current: 3 new: -39, 3
08-19 00:49:09.207 1196-1196/? D/NetworkController﹕ updateWifiState: newRssi=-39 newLevel=3 lastWifiLevel=3 offload=false numLevels=4
08-19 00:49:09.207 963-1155/? E/WifiStateMachine﹕ handleMessage: X
08-19 00:49:09.747 963-1589/? W/ActivityManager﹕ getTasks: caller 10254 does not hold GET_TASKS; limiting output
08-19 00:49:10.157 963-963/? E/WifiTrafficPoller﹕ TRAFFIC_STATS_POLL true Token 2500 num clients 11
08-19 00:49:10.157 963-963/? E/WifiTrafficPoller﹕ packet count Tx=764946 Rx=977505
08-19 00:49:10.157 963-963/? E/WifiTrafficPoller﹕ notifying of data activity 1
08-19 00:49:10.167 1196-1196/? D/NetworkController﹕ [WifiActivity] Connectd: 1
08-19 00:49:10.197 963-963/? D/HtcWifiControlRoamOffload:﹕ Receive mPhoneStateListener
08-19 00:49:10.197 963-963/? D/HtcWifiControlRoamOffload:﹕ Receive mPhoneStateListener, getGsmSignalStrength7
08-19 00:49:10.207 1196-1196/? D/NetworkController﹕ [Strength][1][GSM] SignalStrength: 7 99 -120 -160 -120 -1 -1 99 2147483647 2147483647 2147483647 -1 -1 gsm|lte
08-19 00:49:10.217 1196-1196/? D/NetworkController﹕ [SYSTEMUI_UPDATE_SIGNAL_STRENGTH] level1=0 level2=2
08-19 00:49:10.707 963-1590/? I/art﹕ Explicit concurrent mark sweep GC freed 39093(2MB) AllocSpace objects, 2(296KB) LOS objects, 33% free, 29MB/44MB, paused 1.617ms total 199.088ms
08-19 00:49:10.787 963-1479/? W/ActivityManager﹕ getTasks: caller 10254 does not hold GET_TASKS; limiting output
08-19 00:49:11.187 963-963/? E/WifiTrafficPoller﹕ TRAFFIC_STATS_POLL true Token 2500 num clients 11
08-19 00:49:11.187 963-963/? E/WifiTrafficPoller﹕ packet count Tx=764947 Rx=977505
08-19 00:49:11.187 963-963/? E/WifiTrafficPoller﹕ notifying of data activity 2
08-19 00:49:11.197 1196-1196/? D/NetworkController﹕ [WifiActivity] Connectd: 2
08-19 00:49:11.827 963-1622/? W/ActivityManager﹕ getTasks: caller 10254 does not hold GET_TASKS; limiting output
08-19 00:49:12.197 1196-1431/? I/IntentController﹕ receive(android.provider.Telephony.SPN_STRINGS_UPDATED,1,false)
08-19 00:49:12.197 1441-1441/? D/WifiManager﹕ setCountryCode: Base Package Name=com.android.phone, uid=1001
08-19 00:49:12.197 1441-1441/? D/MccTable﹕ updateMccMncConfiguration mccmnc='null' fromServiceState=true
08-19 00:49:12.197 963-1141/? E/WifiStateMachine﹕ Ignoring resetting of country code
我猜应用程序代码不会抛出异常。
还有一些gradle sync问题，我应该在这做什么？
Warning:The project encoding (windows-1252) does not match the encoding specified in the Gradle build files (UTF-8).
This can lead to serious bugs.
<a href="http://tools.android.com/knownissues/encoding">More Info...</a><br><a href="open.encodings.settings">Open File Encoding Settings</a>
我应该更改项目编码还是gradle构建文件？ 我该如何纠正这个？
logcat堆栈跟踪
08-19 01:11:27.257 5372-5384/? E/AndroidHttpClient﹕ Leak found
java.lang.IllegalStateException: AndroidHttpClient created and never closed
at com.google.android.volley.AndroidHttpClient.<init>(AndroidHttpClient.java:202)
at com.google.android.volley.AndroidHttpClient.newInstance(AndroidHttpClient.java:170)
at com.google.android.volley.GoogleHttpClient.<init>(GoogleHttpClient.java:146)
at com.google.android.volley.GoogleHttpClient.<init>(GoogleHttpClient.java:113)
at com.google.android.finsky.FinskyApp.onCreate(FinskyApp.java:366)
at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1024)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4947)
at android.app.ActivityThread.access$1500(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1424)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:155)
at android.app.ActivityThread.main(ActivityThread.java:5696)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1029)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:824)
当我按下按钮向数据库添加内容时，会发生这种情况
08-19 01:30:25.477 17029-17029/? I/art﹕ Late-enabling -Xcheck:jni
08-19 01:30:25.477 17029-17029/? I/art﹕ VMHOOK: rlim_cur : 0 pid:17029
08-19 01:30:25.517 17029-17039/? I/art﹕ Debugger is no longer active
08-19 01:30:25.687 17029-17029/? D/Atlas﹕ Validating map...
08-19 01:30:25.737 17029-17048/? I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: TEST SBA LA.BF.1.1.1_RB1 AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.00.02.042.012 + c1105519 + c_apilogging ()
OpenGL ES Shader Compiler Version: E031.25.03.00
Build Date: 01/23/15 Fri
Local Branch:
Remote Branch: refs/tags/AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.00.02.042.012
Local Patches: NONE
Reconstruct Branch: NOTHING
08-19 01:30:25.857 17029-17029/? I/InputMethodManager﹕ [startInputInner] EditorInfo { packageName=com.example.vashisht.sqliteapp, inputType=0x20001, imeOptions=0x40000006, privateImeOptions=null }, windowGainingFocus=android.view.ViewRootImpl$W@1287b4e7, mServedView=android.support.v7.widget.AppCompatEditText{e909894 VFED..CL .F....I. 90,222-990,335 #7f0c004f app:id/myinput}, mServedInputConnectionWrapper=android.view.inputmethod.InputMethodManager$ControlledInputConnectionWrapper@18863f3d
08-19 01:30:36.817 17029-17039/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 5.739ms
08-19 01:30:41.217 17029-17044/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 9.796ms
08-19 01:30:42.817 17029-17039/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 6.697ms
08-19 01:30:44.907 17029-17044/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 98(3KB) AllocSpace objects, 58(6MB) LOS objects, 44% free, 4MB/8MB, paused 9.494ms total 18.435ms
08-19 01:30:46.327 17029-17039/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 6.438ms
08-19 01:30:47.017 17029-17044/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 6.799ms
08-19 01:30:47.967 17029-17044/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 9.295ms
08-19 01:30:47.967 17029-17044/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 80(2768B) AllocSpace objects, 46(5MB) LOS objects, 54% free, 3MB/7MB, paused 10.332ms total 23.127ms
08-19 01:30:51.697 17029-17044/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 72(2496B) AllocSpace objects, 42(6MB) LOS objects, 68% free, 1847KB/5MB, paused 7.996ms total 21.588ms
08-19 01:30:57.847 17029-17039/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 5.385ms
08-19 01:31:03.587 17029-17044/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 8.907ms
logcat显示这些暂停线程消息，应用程序仍然冻结，然后我必须杀死应用程序!!
答案 0 :(得分：1)
while循环中缺少moveToNext()方法调用：
while(!c.isAfterLast()) {
if (c.getString(c.getColumnIndex("productname")) != null) {
dbString += c.getString(c.getColumnIndex("productname"));
dbString += "\n";
}
c.moveToNext();
}
答案 1 :(得分：0)
您是否缺少SQLLite游标工厂？
在上面的活动中执行此操作：onCreate：
private SQLiteDatabase.CursorFactory cursorFactory = new SQLiteDatabase.CursorFactory() {
@Override
public Cursor newCursor(SQLiteDatabase db, SQLiteCursorDriver masterQuery, String editTable, SQLiteQuery query) {
// TODO handle cursor creation from passed in query
return null;
}
};
然后修改您的数据库创建：
dbhandler= new MyDBHandler(this, null, cursorFactory, 1);