模拟器不响应此代码。
它将错误称为“不幸，行为已经停止”。 我只用一个字段作为学生名称尝试了相同的代码，它运行良好，但有两个字段作为学生姓名和位置，它没有响应。 请帮帮我。
MainActivity.java
package com.act;
import java.util.List;
import android.app.ListActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.EditText;
public class MainActivity extends ListActivity {
private StudentOperations studentDBoperation;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
studentDBoperation = new StudentOperations(this);
studentDBoperation.open();
List values = studentDBoperation.getAllStudents();
// Use the SimpleCursorAdapter to show the
// elements in a ListView
ArrayAdapter adapter = new ArrayAdapter(this,
android.R.layout.simple_list_item_1, values);
setListAdapter(adapter);
}
public void addUser(View view) {
ArrayAdapter adapter = (ArrayAdapter) getListAdapter();
EditText text = (EditText) findViewById(R.id.editText1);
EditText text2 = (EditText) findViewById(R.id.editText2);
Student stud = studentDBoperation.addStudent(text.getText().toString(),text2.getText().toString());
adapter.add(stud);
}
public void deleteFirstUser(View view) {
ArrayAdapter adapter = (ArrayAdapter) getListAdapter();
Student stud = null;
if (getListAdapter().getCount() > 0) {
stud = (Student) getListAdapter().getItem(0);
studentDBoperation.deleteStudent(stud);
adapter.remove(stud);
}
}
@Override
protected void onResume() {
studentDBoperation.open();
super.onResume();
}
@Override
protected void onPause() {
studentDBoperation.close();
super.onPause();
}
}
DataBaseWrapper.java
package com.act;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DataBaseWrapper extends SQLiteOpenHelper {
public static final String STUD = "Stud";
public static final String STUDENT_ID = "_id";
public static final String STUDENT_NAME = "_name";
public static final String STUDENT_LOC = "_loc";
private static final String DATABASE_NAME = "Students.db";
private static final int DATABASE_VERSION = 1;
// creation SQLite statement
private static final String DATABASE_CREATE = "create table " + STUD
+ "(" + STUDENT_ID + " integer primary key autoincrement, "
+ STUDENT_NAME + " text not null,"
+ STUDENT_LOC + "text not null );";
public DataBaseWrapper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(DATABASE_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// you should do some logging in here
// ..
db.execSQL("DROP TABLE IF EXISTS " + STUD);
onCreate(db);
}
}
Student.java
package com.act;
public class Student {
private int id;
private String name;
private String loc;
public long getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public String getLoc() {
return this.loc;
}
public void setLoc(String loc) {
this.loc = loc;
}
@Override
public String toString() {
return name;
}
}
StudentOperations.java
package com.act;
import java.util.ArrayList;
import java.util.List;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
public class StudentOperations {
// Database fields
private DataBaseWrapper dbHelper;
private String[] STUDENT_TABLE_COLUMNS = { DataBaseWrapper.STUDENT_ID, DataBaseWrapper.STUDENT_NAME,DataBaseWrapper.STUDENT_LOC };
private SQLiteDatabase database;
public StudentOperations(Context context) {
dbHelper = new DataBaseWrapper(context);
}
public void open() throws SQLException {
database = dbHelper.getWritableDatabase();
}
public void close() {
dbHelper.close();
}
public Student addStudent(String name, String loc) {
ContentValues values = new ContentValues();
values.put(DataBaseWrapper.STUDENT_NAME, name);
values.put(DataBaseWrapper.STUDENT_LOC,loc);
long studId = database.insert(DataBaseWrapper.STUD, null, values);
// now that the student is created return it ...
Cursor cursor = database.query(DataBaseWrapper.STUD,
STUDENT_TABLE_COLUMNS, DataBaseWrapper.STUDENT_ID + " = "
+ studId, null, null, null, null);
cursor.moveToFirst();
Student newComment = parseStudent(cursor);
cursor.close();
return newComment;
}
public void deleteStudent(Student comment) {
long id = comment.getId();
System.out.println("Comment deleted with id: " + id);
database.delete(DataBaseWrapper.STUD, DataBaseWrapper.STUDENT_ID
+ " = " + id, null);
}
public List getAllStudents() {
List students = new ArrayList();
Cursor cursor = database.query(DataBaseWrapper.STUD,
STUDENT_TABLE_COLUMNS, null, null, null, null, null);
cursor.moveToFirst();
while (!cursor.isAfterLast()) {
Student student = parseStudent(cursor);
students.add(student);
cursor.moveToNext();
}
cursor.close();
return students;
}
private Student parseStudent(Cursor cursor) {
Student student = new Student();
student.setId((cursor.getInt(0)));
student.setName(cursor.getString(1));
student.setLoc(cursor.getString(2));
return student;
}
}
XML代码 activity_main.xml中
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical" >
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:ems="10" >
<requestFocus />
</EditText>
<Button
android:id="@+id/addBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/editText1"
android:onClick="addUser"
android:text="Add New" />
<Button
android:id="@+id/deleteBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@+id/addBtn"
android:layout_below="@+id/editText1"
android:onClick="deleteFirstUser"
android:text="Delete First" />
<ListView
android:id="@android:id/list"
android:layout_width="match_parent"
android:layout_height="212dp"
android:layout_alignParentLeft="true"
android:layout_below="@+id/deleteBtn" >
</ListView>
<EditText
android:id="@+id/editText2"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
logcat的：
02-27 05:13:53.349: D/dalvikvm(1057): GC_FOR_ALLOC freed 52K, 6% free 2878K/3036K, paused 35ms, total 37ms
02-27 05:13:53.389: D/dalvikvm(1057): GC_FOR_ALLOC freed 4K, 6% free 2972K/3136K, paused 26ms, total 26ms
02-27 05:13:53.399: I/dalvikvm-heap(1057): Grow heap (frag case) to 4.074MB for 1127536-byte allocation
02-27 05:13:53.509: D/dalvikvm(1057): GC_FOR_ALLOC freed <1K, 4% free 4073K/4240K, paused 108ms, total 108ms
02-27 05:13:53.650: E/SQLiteLog(1057): (1) near ")": syntax error
02-27 05:13:53.650: D/AndroidRuntime(1057): Shutting down VM
02-27 05:13:53.650: W/dalvikvm(1057): threadid=1: thread exiting with uncaught exception (group=0x414c4700)
02-27 05:13:53.670: E/AndroidRuntime(1057): FATAL EXCEPTION: main
02-27 05:13:53.670: E/AndroidRuntime(1057): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.act/com.act.MainActivity}: android.database.sqlite.SQLiteException: near ")": syntax error (code 1): , while compiling: create table Stud(_id integer primary key autoincrement, _name text not null,);
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.app.ActivityThread.access$600(ActivityThread.java:141)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.os.Handler.dispatchMessage(Handler.java:99)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.os.Looper.loop(Looper.java:137)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.app.ActivityThread.main(ActivityThread.java:5103)
02-27 05:13:53.670: E/AndroidRuntime(1057): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 05:13:53.670: E/AndroidRuntime(1057): at java.lang.reflect.Method.invoke(Method.java:525)
02-27 05:13:53.670: E/AndroidRuntime(1057): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
02-27 05:13:53.670: E/AndroidRuntime(1057): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
02-27 05:13:53.670: E/AndroidRuntime(1057): at dalvik.system.NativeStart.main(Native Method)
02-27 05:13:53.670: E/AndroidRuntime(1057): Caused by: android.database.sqlite.SQLiteException: near ")": syntax error (code 1): , while compiling: create table Stud(_id integer primary key autoincrement, _name text not null,);
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1672)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1603)
02-27 05:13:53.670: E/AndroidRuntime(1057): at com.act.DataBaseWrapper.onCreate(DataBaseWrapper.java:26)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:252)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
02-27 05:13:53.670: E/AndroidRuntime(1057): at com.act.StudentOperations.open(StudentOperations.java:19)
02-27 05:13:53.670: E/AndroidRuntime(1057): at com.act.MainActivity.onCreate(MainActivity.java:19)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.app.Activity.performCreate(Activity.java:5133)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
02-27 05:13:53.670: E/AndroidRuntime(1057): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
02-27 05:13:53.670: E/AndroidRuntime(1057):
答案 0 :(得分：1)
检查此行
02-27 05:13:53.670: E/AndroidRuntime(1057): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.act/com.act.MainActivity}: android.database.sqlite.SQLiteException: near ")": syntax error (code 1): , while compiling: create table Stud(_id integer primary key autoincrement, _name text not null,);
更改此行
创建表Stud(_id integer primary key autoincrement, _name text not null,);
作为
create table Stud(_id integer primary key autoincrement, _name text not null);
答案 1 :(得分：0)
我认为您在STUDENT_LOC + "text not null );之间的text not null错过了空间，因此请使用此STUDENT_LOC + " text not null );替换它，以便您的整个查询应该如此，请尝试如下。
而且你错过了关闭" STUDENT_LOC的编辑，请验证它。
private static final String DATABASE_CREATE = "create table " + STUD
+ "(" + STUDENT_ID + " integer primary key autoincrement, "
+ STUDENT_NAME + " text not null,"
+ STUDENT_LOC + " text not null " )";
public DataBaseWrapper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}