我創建了一個簡單的應用程序，它存儲了一個人的緊急聯繫人詳細信息，例如姓名，血型，聯繫電話號碼並以文本視圖顯示。所有這一切都應該當我點擊保存按鈕，調用saveMe（）方法，但要發生時，我做的是應用程序只是崩潰了，請大家幫忙代碼和日誌貓下面貼Android簡單數據庫應用程序獲取錯誤
數據庫代碼
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)
*/
@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;
}
}
詳細類
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;
}
}
主要活動（這其中所有的數據將被顯示）
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);
}
}
編輯屏幕 - 屏幕，所有的編輯文本，它與保存按鈕
package com.example.androidsimpledbapp1;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
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);
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);
}
}
登錄貓屏幕 - 錯誤
08-08 21：58：33.896：E/AndroidRuntime（368） ：致命例外：main 08-08 21：58：33.896：E/AndroidRuntime（368）：java.lang.IllegalStateException：無法執行活動的方法 08-08 21：58：33.896：E/AndroidRuntime（368） ）：at android.view.View $ 1.onClick（View.java:2144） 08-08 21：58：33.896：E/AndroidRuntime（368）：at android.view.View.performClick（View.java:2485） 08-08 21：58：33.896： E/AndroidRuntime（368）：在android.view.View $ PerformClick.run（View.java:9080） 08-08 21：58：33.896：E/AndroidRuntime（368）：at android.os.Handler.handleCallback Handler.java:587） 08-08 21：58：33.896：E/AndroidRuntime（368）：at android.os.Handler.dispatchMessage（Handler.java:92） 08-08 21：58：33.896：E/AndroidRuntime（368）：在android.os.Looper.loop（Looper.java:130） 08-08 21：58：33.896：E/AndroidRuntime（368）：在android.app.ActivityThread.main（ActivityThread.java： E/AndroidRuntime（368）：E/AndroidRuntime（368）：at java.lang.reflect.Method.invokeNative（Native Method） 08-08 21：58：33.896：E/AndroidRuntime在java.lang.reflect.Method.invoke（Method.java:507） 08-08 21：58：33.896：E/AndroidRuntime（368）：at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit .ja va：839） 08-08 21：58：33.896：E/AndroidRuntime（368）：at com.android.internal.os.ZygoteInit.main（ZygoteInit.java:597） 08-08 21：58：33.896： E/AndroidRuntime（368）：at dalvik.system.NativeStart.main（Native Method） 08-08 21：58：33.896：E/AndroidRuntime（368）：引起：java.lang.reflect.InvocationTargetException 08-08 21:58：33.896：E/AndroidRuntime（368）：at java.lang.reflect.Method.invokeNative（Native Method） 08-08 21：58：33.896：E/AndroidRuntime（368）：at java.lang.reflect .Method.invoke（Method.java:507） 08-08 21：58：33.896：E/AndroidRuntime（368）：at android.view.View $ 1.onClick（View.java:2139） 08-08 21： 58：33.896：E/AndroidRuntime（368）：... 11更多 08-08 21：58：33.896：E/AndroidRuntime（368）：引起：java.lang.NullPointerException 08-08 21：58：33.896：E/AndroidRuntime（368）：at com.example.androidsimpledbapp1.EditScreen.saveMe（EditScreen.java:38） 08-08 21：58：33.896：E/AndroidRuntime（368） ：... 14更多
錯字，您忘記了逗號，請學習如何使用堆棧跟蹤 – Selvin
代碼中的拼寫錯誤在哪裏？ –