Question

这篇文章与Creating multiple Tables and inserting Data into them有关所以我修复了我只有一个表被创建的问题。但是现在当我尝试切换活动时应用程序会崩溃。我的MainActivity仍然有效。

这是崩溃的类/活动之一。另一个是相似的，唯一的区别是按钮和textedits的名称。

public class FachErstellen extends AppCompatActivity {

DatabaseHelper myDb;
EditText editTextFachName;
EditText editTextFachKuerzel;
EditText editTextFachRaum;
EditText editTextFachLehrer;
Button buttonFachSpeichern;








@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fach_erstellen_activity);

    myDb = new DatabaseHelper(this);
    myDb.fuegeNeueTabellenHinzu();
    editTextFachName = (EditText) findViewById(R.id.editTextFachName);
    editTextFachKuerzel = (EditText) findViewById(R.id.editTextFachKuerzel);
    editTextFachRaum = (EditText) findViewById(R.id.editTextFachRaum);
    editTextFachLehrer = (EditText) findViewById(R.id.editTextFachLehrer);
    buttonFachSpeichern = (Button) findViewById(R.id.buttonFachSpeichern);

    addFach();
    zeigeFaecher();


}

public void addFach(){
    buttonFachSpeichern.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            boolean istGespeichert = myDb.speichereFach(editTextFachName.getText().toString(),
                    editTextFachKuerzel.getText().toString(),
                    editTextFachRaum.getText().toString(),
                    editTextFachLehrer.getText().toString());
            if (istGespeichert==true){
                Toast.makeText(FachErstellen.this, "Fach wurde gespeichert.", Toast.LENGTH_LONG).show();
            }
            else {
                Toast.makeText(FachErstellen.this, "Fach konnte nicht gespeichert werden.", Toast.LENGTH_LONG).show();
            }
        }
    });

}

public void zeigeFaecher(){
    buttonFaecherAnzeigen.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Cursor res = myDb.zeigeFaecher();
            if (res.getCount() == 0) {
                zeigeNachricht("Fehler", "Keine Fächer gefunden");
                return;
            }

            StringBuffer buffer = new StringBuffer();
            while (res.moveToNext()){
                buffer.append("ID:" + res.getString(0)+"\n");
                buffer.append("Fach: " + res.getString(1)+"\n");
                buffer.append("Kürzel: " + res.getString(2)+"\n");
                buffer.append("Raum: " + res.getString(3)+"\n");
                buffer.append("Lehrer: " + res.getString(4)+"\n\n");
            }

            zeigeNachricht("Fächer", buffer.toString());
        }
    });
}

public void zeigeNachricht(String title, String Nachricht){
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setCancelable(true);
    builder.setTitle(title);
    builder.setMessage(Nachricht);
    builder.show();

}

- 并遵循gradle文件

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {

    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'


        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

-

和崩溃信息

    Increasing code cache capacity to 128KB
05-29 15:15:28.150 15952-15952/jannikokan.de.stundenplan D/MeineAPP: DB angelegt
05-29 15:15:28.154 15952-15952/jannikokan.de.stundenplan E/SQLiteLog: (1) AUTOINCREMENT is only allowed on an INTEGER PRIMARY KEY
05-29 15:15:28.154 15952-15952/jannikokan.de.stundenplan D/AndroidRuntime: Shutting down VM
05-29 15:15:28.155 15952-15952/jannikokan.de.stundenplan E/AndroidRuntime: FATAL EXCEPTION: main
    Process: jannikokan.de.stundenplan, PID: 15952
    java.lang.RuntimeException: Unable to start activity ComponentInfo{jannikokan.de.stundenplan/jannikokan.de.stundenplan.LehrerErstellen}: android.database.sqlite.SQLiteException: AUTOINCREMENT is only allowed on an INTEGER PRIMARY KEY (code 1): , while compiling: create table Lehrer_table(ID_LINTEGER PRIMARY KEY AUTOINCREMENT,LEHRERNAMETEXT,LEHRERKUERZELTEXT,LEHRERRAUMTEXT,LEHRERMAILTEXT)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6077)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
     Caused by: android.database.sqlite.SQLiteException: AUTOINCREMENT is only allowed on an INTEGER PRIMARY KEY (code 1): , while compiling: create table Lehrer_table(ID_LINTEGER PRIMARY KEY AUTOINCREMENT,LEHRERNAMETEXT,LEHRERKUERZELTEXT,LEHRERRAUMTEXT,LEHRERMAILTEXT)
        at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
        at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
        at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
        at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
        at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
        at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
        at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1677)
        at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1608)
        at jannikokan.de.stundenplan.DatabaseHelper.CheckeUndErstelleTabelle(DatabaseHelper.java:114)
        at jannikokan.de.stundenplan.DatabaseHelper.erstelleTabellenDieNichtExistieren(DatabaseHelper.java:98)
        at jannikokan.de.stundenplan.DatabaseHelper.fuegeNeueTabellenHinzu(DatabaseHelper.java:80)
        at jannikokan.de.stundenplan.LehrerErstellen.onCreate(LehrerErstellen.java:36)
        at android.app.Activity.performCreate(Activity.java:6662)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
        at android.app.ActivityThread.-wrap12(ActivityThread.java) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:154) 
        at android.app.ActivityThread.main(ActivityThread.java:6077) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756) 
05-29 15:15:28.155 1595-1606/? W/ActivityManager:   Force finishing activity jannikokan.de.stundenplan/.LehrerErstellen
05-29 15:15:28.158 1595-1606/? W/ActivityManager:   Force finishing activity jannikokan.de.stundenplan/.SliderActivityActivity
05-29 15:15:28.196 1595-1636/? I/OpenGLRenderer: Initialized EGL, version 1.4
05-29 15:15:28.196 1595-1636/? D/OpenGLRenderer: Swap behavior 1
05-29 15:15:28.196 1595-1636/? W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
05-29 15:15:28.196 1595-1636/? D/OpenGLRenderer: Swap behavior 0
05-29 15:15:28.200 1595-1636/? D/EGL_emulation: eglCreateContext: 0xa350f6c0: maj 2 min 0 rcv 2
05-29 15:15:28.211 1595-1636/? D/EGL_emulation: eglMakeCurrent: 0xa350f6c0: ver 2 0 (tinfo 0x974e53b0)
05-29 15:15:28.218 1595-1636/? D/EGL_emulation: eglMakeCurrent: 0xa350f6c0: ver 2 0 (tinfo 0x974e53b0)
05-29 15:15:28.660 1595-1608/? W/ActivityManager: Activity pause timeout for ActivityRecord{17375b u0 jannikokan.de.stundenplan/.LehrerErstellen t103 f}
05-29 15:15:28.779 1996-2119/? D/EGL_emulation: eglMakeCurrent: 0xa5e052a0: ver 2 0 (tinfo 0xa5e03630)
05-29 15:15:29.294 1996-2119/? W/OpenGLRenderer: Incorrectly called buildLayer on View: ShortcutAndWidgetContainer, destroying layer...
05-29 15:15:31.327 1353-1378/? W/audio_hw_generic: Not supplying enough data to HAL, expected position 7930259 , only wrote 7777440

提前感谢您的帮助！

Answer 1

此异常的原因是您在创建表时为列添加了1.5以外的其他内容。

更具体地说，你有： -

?? INTEGER PRIMARY KEY AUTOINCREMENT

这应该是： -

create table Lehrer_table(ID_LINTEGER PRIMARY KEY AUTOINCREMENT,LEHRERNAMETEXT,LEHRERKUERZELTEXT,LEHRERRAUMTEXT,LEHRERMAILTEXT)

即。在 create table Lehrer_table(ID_L INTEGER PRIMARY KEY AUTOINCREMENT,LEHRERNAMETEXT,LEHRERKUERZELTEXT,LEHRERRAUMTEXT,LEHRERMAILTEXT) 和 ID_L 之间添加了一个空格，因此 INTEGER 变为 {{ 1}}

说你使用ID_LINTEGER很可能是不必要的，因为它消耗了更多的资源而有害。

ID_L INTEGER所做的只是确保下一个 ID 将大于之前的版本（在您达到9223372036854775807行之前，它很可能会一直存在）。如果使用AUTOINCREMENT达到该数字，则您将无法插入行，因为插入将具有 SQLITE_FULL 异常。同时，如果没有AUTOINCREMENT，可能会分配一个现在未使用的ID。

引用SQLIte文档： -




AUTOINCREMENT关键字会占用额外的CPU，内存，磁盘空间和   磁盘I / O开销，如果不是严格需要，应该避免。它是   通常不需要。



在SQLite中，类型为INTEGER PRIMARY KEY的列是其中的别名   ROWID（除非在WITHOUT ROWID表中），它总是64位签名   整数。



在INSERT上，如果不是ROWID或INTEGER PRIMARY KEY列   明确给出一个值，然后它会自动填充一个   未使用的整数，通常比当前最大的ROWID多一个   使用。无论AUTOINCREMENT是否正确，都是如此   使用关键字。



如果在INTEGER PRIMARY KEY之后出现AUTOINCREMENT关键字，那么   更改自动ROWID分配算法以防止重用   在数据库的生命周期中的ROWID。换句话说，   AUTOINCREMENT的目的是防止重用ROWID   以前删除的行。



因此我建议使用： -

AUTOINCREMENT

应用程序崩溃而未进行任何更改

1 个答案: