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我创建了一个简单的Android应用程序，要求用户输入姓名，血型，联系电话等信息，将其保存到数据库中，并显示在另一个屏幕上。当点击保存按钮调用saveMe()方法时，这一切都会发生。然而，当我点击保存按钮，应用程序不会崩溃，靠近而是卡住，然后在logcat我看到的是这样的：Android数据库应用程序出错
08-08 22:41:23.734: D/dalvikvm(365): GC_FOR_MALLOC freed 321K, 50% free 2984K/5959K, external 716K/1038K, paused 18ms
08-08 22:41:23.754: D/dalvikvm(365): GC_FOR_MALLOC freed 322K, 50% free 2984K/5959K, external 716K/1038K, paused 18ms
08-08 22:41:23.784: D/dalvikvm(365): GC_FOR_MALLOC freed 323K, 50% free 2984K/5959K, external 716K/1038K, paused 21ms
08-08 22:41:23.804: D/dalvikvm(365): GC_FOR_MALLOC freed 324K, 50% free 2984K/5959K, external 716K/1038K, paused 19ms
08-08 22:41:23.824: D/dalvikvm(365): GC_FOR_MALLOC freed 324K, 50% free 2984K/5959K, external 716K/1038K, paused 20ms
08-08 22:41:23.844: D/dalvikvm(365): GC_FOR_MALLOC freed 325K, 50% free 2984K/5959K, external 716K/1038K, paused 20ms
08-08 22:41:23.874: D/dalvikvm(365): GC_FOR_MALLOC freed 326K, 50% free 2984K/5959K, external 716K/1038K, paused 25ms
08-08 22:41:23.894: D/dalvikvm(365): GC_FOR_MALLOC freed 327K, 50% free 2984K/5959K, external 716K/1038K, paused 23ms
08-08 22:41:23.934: D/dalvikvm(365): GC_FOR_MALLOC freed 327K, 50% free
这些消息不断出现在日志中的猫。我可以阻止它们的唯一方法是关闭模拟器。应用程序是否陷入了无限循环？没有数据被保存或显示。
数据库类
package com.example.androidsimpledbapp1;
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 {
/*
* Class for Working with DB
*/
//Update each time DB structure changes e.g. adding new property
private static final int DATABASE_VERSION =1;
//DB Name
private static final String DATABASE_NAME = "deets.db";
//Table name
public static final String TABLE_PRODUCTS = "products";
//DB Columns
public static final String COLUMN_ID = "_Id";
public static final String COLUMN_PERSONNAME = "firstName";
public static final String COLUMN_PERSONBLOOD = "bloodType";
public static final String COLUMN_PERSONCONTACT = "contactName";
public static final String COLUMN_PERSONNUMBER = "phoneNumber";
public static final String COLUMN_PERSONRELATION = "relationship";
//Constructor
/*
* Passing information to super class in SQL
* Context is background information
* name of db
* Database version
*/
public MyDBHandler(Context context, String name, SQLiteDatabase.CursorFactory factory, int version){
super(context, DATABASE_NAME, factory, DATABASE_VERSION);
}
/*
* What to do first time when you create DB
* Creates the table the very first time
* (non-Javadoc)
* @see android.database.sqlite.SQLiteOpenHelper#onCreate(android.database.sqlite.SQLiteDatabase)
* Remember to use Commas as shown below
*/
@Override
public void onCreate(SQLiteDatabase db){
String query = "CREATE TABLE "+ TABLE_PRODUCTS + "(" +
COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "+
COLUMN_PERSONNAME + " TEXT, "+
COLUMN_PERSONBLOOD + " TEXT, "+
COLUMN_PERSONCONTACT + " TEXT, "+
COLUMN_PERSONNUMBER + " TEXT, " +
COLUMN_PERSONRELATION + " TEXT " +
");";
//Execute the query
db.execSQL(query);
}
/*
* If ever upgrading DB call this method
* (non-Javadoc)
* @see android.database.sqlite.SQLiteOpenHelper#onUpgrade(android.database.sqlite.SQLiteDatabase, int, int)
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
//Delete the current table
db.execSQL("DROP TABLE IF EXISTS" + TABLE_PRODUCTS);
//create new table
onCreate(db);
}
//Add new row to the database
public void addProduct(Details details){
//Built in class - set values for different columns
//Makes inserting rows quick and easy
ContentValues values = new ContentValues();
values.put(COLUMN_PERSONNAME, details.get_firstName());
values.put(COLUMN_PERSONBLOOD, details.get_bloodType());
values.put(COLUMN_PERSONCONTACT, details.get_contactName());
values.put(COLUMN_PERSONNUMBER, details.get_phoneNumber());
values.put(COLUMN_PERSONRELATION, details.get_relationship());
SQLiteDatabase db = getWritableDatabase();
db.insert(TABLE_PRODUCTS, null, values);
db.close();
}
/*
public void deleteProducts(){
SQLiteDatabase = getWritableDatabase();
db.execSQL("DROP TABLE");
How to delete the database...
}
*/
//Take DB and Convert to String
public String databaseToString(){
String dbString = "";
SQLiteDatabase db = getWritableDatabase();
//Every Column and row
String query = "SELECT * FROM " + TABLE_PRODUCTS + " WHERE 1";
//Cursor points to a location in your results
//First row point here, second row point here
Cursor c = db.rawQuery(query, null);
c.moveToFirst();
while(!c.isAfterLast()){
//Extracts first name and adds to string
if(c.getString(c.getColumnIndex("firstName"))!=null){
dbString += c.getString(c.getColumnIndex("firstName"));
/*
* Displaying all other columns
*/
}
}
db.close();
return dbString;
}
}
详细类
package com.example.androidsimpledbapp1;
public class Details {
//primary key
private int _id;
//Properties
private String _firstName;
private String _bloodType;
private String _contactName;
private String _phoneNumber;
private String _relationship;
//Dont Have to Enter Everything each time
public Details(){
}
public Details(String firstName){
this.set_firstName(firstName);
}
//Passing in details
//Setting values from the user
public Details(String firstName, String bloodType,
String contactName, String phoneNumber,
String relationship){
this.set_firstName(firstName);
this.set_bloodType(bloodType);
this.set_contactName(contactName);
this.set_phoneNumber(phoneNumber);
this.set_relationship(relationship);
}
//Retrieve the data
public int get_id() {
return _id;
}
//Setter allows to give property
public void set_id(int _id) {
this._id = _id;
}
public String get_firstName() {
return _firstName;
}
public void set_firstName(String _firstName) {
this._firstName = _firstName;
}
public String get_bloodType() {
return _bloodType;
}
public void set_bloodType(String _bloodType) {
this._bloodType = _bloodType;
}
public String get_contactName() {
return _contactName;
}
public void set_contactName(String _contactName) {
this._contactName = _contactName;
}
public String get_phoneNumber() {
return _phoneNumber;
}
public void set_phoneNumber(String _phoneNumber) {
this._phoneNumber = _phoneNumber;
}
public String get_relationship() {
return _relationship;
}
public void set_relationship(String _relationship) {
this._relationship = _relationship;
}
}
编辑屏幕 - 当保存按钮被点击
public class EditScreen extends Activity {
EditText firstNameInput;
EditText bloodTypeInput;
EditText contacNameInput;
EditText phoneNumberInput;
EditText relationshipInput;
TextView displayName;
MyDBHandler dbHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_edit_screen);
firstNameInput = (EditText) findViewById(R.id.inputname);
bloodTypeInput = (EditText) findViewById(R.id.inputblood);
contacNameInput = (EditText) findViewById(R.id.inputcontact);
phoneNumberInput = (EditText) findViewById(R.id.inputnum);
relationshipInput = (EditText) findViewById(R.id.inputraltion);
displayName = (TextView) findViewById(R.id.dbname);
dbHandler = new MyDBHandler(this, null, null, 1);
}
/*
* Causing error fix the error
*/
public void saveMe(View v){
Details detail = new Details(firstNameInput.getText().toString(),
bloodTypeInput.getText().toString(),
contacNameInput.getText().toString(),
phoneNumberInput.getText().toString(),
relationshipInput.getText().toString()
);
dbHandler.addProduct(detail);
printDatabase();
}
private void printDatabase() {
//Taking the string
String dbString = dbHandler.databaseToString();
//Display in the textview
displayName.setText(dbString);
}
}
主要活动
package com.example.androidsimpledbapp1;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
//Changing Activity
public void editBtnPressed(View v){
Intent intent = new Intent(MainActivity.this, EditScreen.class);
startActivity(intent);
}
}
logcat的 - 错误
08-08 22:41:00.034: D/AndroidRuntime(348): >>>>>> AndroidRuntime START com.android.internal.os.RuntimeInit <<<<<<
08-08 22:41:00.054: D/AndroidRuntime(348): CheckJNI is ON
08-08 22:41:00.273: I/ActivityManager(60): Start proc com.svox.pico for broadcast com.svox.pico/.VoiceDataInstallerReceiver: pid=350 uid=10028 gids={}
08-08 22:41:00.583: I/ActivityThread(350): Pub com.svox.pico.providers.SettingsProvider: com.svox.pico.providers.SettingsProvider
08-08 22:41:00.663: D/GTalkService(185): handlePackageInstalled: re-initialize providers
08-08 22:41:00.663: D/GTalkService(185): [RawStanzaProvidersMgr] ##### searchProvidersFromIntent
08-08 22:41:00.663: D/GTalkService(185): [RawStanzaProvidersMgr] no intent receivers found
08-08 22:41:00.713: D/dalvikvm(335): GC_CONCURRENT freed 211K, 43% free 3575K/6215K, external 716K/1038K, paused 3ms+4ms
08-08 22:41:00.874: D/AndroidRuntime(348): Calling main entry com.android.commands.am.Am
08-08 22:41:00.904: I/ActivityManager(60): Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.example.androidsimpledbapp1/.MainActivity } from pid 348
08-08 22:41:00.974: D/AndroidRuntime(348): Shutting down VM
08-08 22:41:00.984: I/ActivityManager(60): Start proc com.example.androidsimpledbapp1 for activity com.example.androidsimpledbapp1/.MainActivity: pid=365 uid=10045 gids={}
08-08 22:41:00.994: D/dalvikvm(348): GC_CONCURRENT freed 101K, 69% free 318K/1024K, external 0K/0K, paused 1ms+1ms
08-08 22:41:01.004: D/jdwp(348): adbd disconnected
08-08 22:41:01.154: D/dalvikvm(32): GC_EXPLICIT freed 11K, 50% free 2719K/5379K, external 716K/1038K, paused 168ms
08-08 22:41:01.214: D/dalvikvm(32): GC_EXPLICIT freed <1K, 50% free 2719K/5379K, external 716K/1038K, paused 62ms
在哪行后面添加？ –