String getId=db1.getId().toString();
和
SQLiteDatabase db=this.getReadableDatabase();
在logcat的android程序中给出错误。 '过滤错误的Logcat数据'
04-16 03:10:09.769: E/dalvikvm(26422): Unable to open stack trace file '/data/anr/traces.txt': Is a directory
04-16 03:10:10.109: E/AndroidRuntime(26422): FATAL EXCEPTION: main
04-16 03:10:10.109: E/AndroidRuntime(26422): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.doctors.prescription/com.doctors.prescription.ThirdActivity}: java.lang.NullPointerException
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.app.ActivityThread.access$600(ActivityThread.java:123)
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.os.Handler.dispatchMessage(Handler.java:99)
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.os.Looper.loop(Looper.java:137)
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.app.ActivityThread.main(ActivityThread.java:4424)
04-16 03:10:10.109: E/AndroidRuntime(26422): at java.lang.reflect.Method.invokeNative(Native Method)
04-16 03:10:10.109: E/AndroidRuntime(26422): at java.lang.reflect.Method.invoke(Method.java:511)
04-16 03:10:10.109: E/AndroidRuntime(26422): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
04-16 03:10:10.109: E/AndroidRuntime(26422): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
04-16 03:10:10.109: E/AndroidRuntime(26422): at dalvik.system.NativeStart.main(Native Method)
04-16 03:10:10.109: E/AndroidRuntime(26422): Caused by: java.lang.NullPointerException
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:157)
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:231)
04-16 03:10:10.109: E/AndroidRuntime(26422): at com.doctors.prescription.ThirdActivityDb.selectOne(ThirdActivityDb.java:67)
04-16 03:10:10.109: E/AndroidRuntime(26422): at com.doctors.prescription.ThirdActivity.onCreate(ThirdActivity.java:50)
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.app.Activity.performCreate(Activity.java:4465)
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
04-16 03:10:10.109: E/AndroidRuntime(26422): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
04-16 03:10:10.109: E/AndroidRuntime(26422): ... 11 more
'数据库文件'
package com.doctors.prescription;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.provider.BaseColumns;
public class ThirdActivityDb extends SQLiteOpenHelper{
public static final String KEY_ID = "id";
public static final String KEY_NAME = "name";
public static final String KEY_AGE = "age";
public static final String KEY_GENDER = "gender";
public static final String KEY_NUMBER = "number";
public static final String KEY_EMAIL = "email";
private static final String DATABASE_NAME = "Doctordb";
private static final String DATABASE_TABLE = "doctor_register";
private static final int DATABASE_VERSION = 2;
private static final String CREATE_TABLE_QUERY = "CREATE TABLE "
+ ThirdActivityDb.DATABASE_NAME + " (" + ThirdActivityDb.KEY_ID
+ " INTEGER PRIMARY KEY AUTO INCREMENT , "
+ ThirdActivityDb.KEY_NAME + " VARCHAR," + ThirdActivityDb.KEY_AGE
+ " VARCHAR," + ThirdActivityDb.KEY_GENDER + " VARCHAR,"
+ ThirdActivityDb.KEY_NUMBER + " VARCHAR,"
+ ThirdActivityDb.KEY_EMAIL + " VARCHAR)";
public ThirdActivityDb(Context context, String name, CursorFactory factory,
int version) {
super(context, DATABASE_NAME, factory, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL(CREATE_TABLE_QUERY);
onCreate(db);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
onUpgrade(db, 0,DATABASE_VERSION);
}
public void InsertData(String name,String age,String gender,String number,String email){
SQLiteDatabase db=this.getWritableDatabase();
ContentValues contentvalue=new ContentValues();
contentvalue.put("name", name);
contentvalue.put("age", age);
contentvalue.put("gender", gender);
contentvalue.put("number", number);
contentvalue.put("email", email);
db.insert("doctor_register", null, contentvalue);
db.close();
}
public Cursor selectOne(String id)
{
SQLiteDatabase db=this.getReadableDatabase();
String query = "select id from doctor_register order by id desc limit 1 ";
Cursor c= db.rawQuery(query, new String[]{id});
if(c.getCount()!=0)
{
return c;
}
return null;
}
public Cursor select(String id , String name)
{
SQLiteDatabase db=this.getReadableDatabase();
String query = "select name from doctor_register where id="+id+" and name="+name;
Cursor c= db.rawQuery(query, new String[]{name});
if(c.getCount()!=0)
{
return c;
}
return null;
}
public Cursor getId(){
SQLiteDatabase db=this.getReadableDatabase();
Cursor c = db.rawQuery("select id from doctor_register order by id desc limit 1 " ,null );
if(c.getCount()!=0)
return c;
return null;
}
}
'ThirdActivity.class'
package com.doctors.prescription;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.pm.ActivityInfo;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
public class ThirdActivity extends Activity {
Button third_create, third_cancel;
EditText name, age, number, email;
TextView generated_id;
private RadioGroup radio_group;
RadioButton radio_Gender;
int radio_id;
String KEY_ID="KEY_ID";
String KEY_GETID="KEY_GETID";
ThirdActivityDb db1 = new ThirdActivityDb(null, null, null, 2);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_third);
//requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
name = (EditText) findViewById(R.id.third_editText1);
age = (EditText) findViewById(R.id.third_editText2);
radio_group=(RadioGroup)findViewById(R.id.radioGroup1);
number = (EditText) findViewById(R.id.third_editText3);
email = (EditText) findViewById(R.id.third_editText4);
String getId=db1.getId().toString();
SharedPreferences SPref=getPreferences(MODE_PRIVATE);
SharedPreferences.Editor editor=SPref.edit();
editor.putString(KEY_ID, getId);
editor.commit();
String id = SPref.getString(KEY_GETID, KEY_GETID );
generated_id = (TextView) findViewById(R.id.generated_id);
String s=db1.selectOne(id).toString();
generated_id.setText(s);
third_create = (Button) findViewById(R.id.third_create_new);
third_create.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (name.getText().toString().length() == 0
|| age.getText().toString().length() == 0
|| number.getText().toString().length() == 0
/* || email.getText().toString().length() == 0 */) {
name.setError("Please enter the name of patient!");
age.setError("Please enter the age of patient");
number.setError("Please enter the contact number of patient");
email.setError("Please enter the email of patient");
} else {
//generated_id.setText(db.getRecord(TRIM_MEMORY_UI_HIDDEN).toString());
int selected_id = radio_group.getCheckedRadioButtonId();
radio_Gender = (RadioButton) findViewById(selected_id);
db1.InsertData(name.getText().toString(), age
.getText().toString(), radio_Gender.getText().toString(),
number.getText().toString(), email.getText()
.toString());
db1.close();
Intent intent = new Intent(getApplicationContext(),
WriteTextActivity.class);
startActivity(intent);
}
}
});
third_cancel = (Button) findViewById(R.id.third_cancel);
third_cancel.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent = new Intent(getApplicationContext(),
SecondActivity.class);
startActivity(intent);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.third, menu);
return true;
}
}
提前致谢。
答案 0 :(得分：2)
我可以在代码中看到一些问题，CREATE_TABLE_QUERY您正在使用DATABASE_NAME代替DATABASE_TABLE
private static final String CREATE_TABLE_QUERY = "CREATE TABLE "
+ ThirdActivityDb.DATABASE_TABLE + " (" + ThirdActivityDb.KEY_ID
+ " INTEGER PRIMARY KEY AUTO INCREMENT , "
+ ThirdActivityDb.KEY_NAME + " VARCHAR," + ThirdActivityDb.KEY_AGE
+ " VARCHAR," + ThirdActivityDb.KEY_GENDER + " VARCHAR,"
+ ThirdActivityDb.KEY_NUMBER + " VARCHAR,"
+ ThirdActivityDb.KEY_EMAIL + " VARCHAR)";
从onCreate(db);方法
onCreate(SQLiteDatabase db)
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL(CREATE_TABLE_QUERY);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
// Create tables again
onCreate(db);
}
我不确定这是否会导致问题implements BaseColumns尝试删除它。
<强>被修改
public String getId(){
SQLiteDatabase db=this.getReadableDatabase();
Cursor c = db.rawQuery("select id from doctor_register order by id desc limit 1 " ,null );
if(c.getCount() > 0) {
c.moveToFirst();
return c.getString(0);
}
return null;
}
呼叫
String getId = db1.getId();
答案 1 :(得分：0)
您只创建表Doctordb，但尝试查询表doctor_register
String query = "select name from doctor_register where id="+id+" and name="+name;