Question

在我发布的上一个问题中（包含所有代码）

Unable to substantiate activity ComponentInfo - Null Pointer Exception

我有一个nullexception错误，如果击败那个运行时错误，我已经绊倒了另一个。日志猫是：

03-14 17:43:25.169: ERROR/AndroidRuntime(339): FATAL EXCEPTION: main
03-14 17:43:25.169: ERROR/AndroidRuntime(339): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.android.dbtest/com.android.dbtest.ShowActivity}: java.lang.IllegalArgumentException: column '_id' does not exist
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1622)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1638)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:928)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.os.Looper.loop(Looper.java:123)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.app.ActivityThread.main(ActivityThread.java:3647)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at java.lang.reflect.Method.invokeNative(Native Method)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at java.lang.reflect.Method.invoke(Method.java:507)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at dalvik.system.NativeStart.main(Native Method)
03-14 17:43:25.169: ERROR/AndroidRuntime(339): Caused by: java.lang.IllegalArgumentException: column '_id' does not exist
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:314)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.widget.CursorAdapter.init(CursorAdapter.java:111)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.widget.CursorAdapter.<init>(CursorAdapter.java:90)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.widget.ResourceCursorAdapter.<init>(ResourceCursorAdapter.java:47)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.widget.SimpleCursorAdapter.<init>(SimpleCursorAdapter.java:84)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at com.android.dbtest.ShowActivity.onCreate(ShowActivity.java:45)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1586)
03-14 17:43:25.169: ERROR/AndroidRuntime(339):     ... 11 more

一旦按下“显示”按钮并启动ShowActivity，就会出现此问题（上述链接的答案是关于在何处初始化listcontent） - 但是，由于colum _id，它现在似乎失败了。据我所知，这是在我的适配器中启动的。

任何帮助，非常好。

编辑：添加以下代码 - 并在下面添加评论

package com.android.dbtest;

import android.database.Cursor;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.SimpleCursorAdapter;

public class AddActivity extends DatabaseTestActivity{

private SQLiteAdapter mySQLiteAdapter;
private String jobId;

SimpleCursorAdapter cursorAdapter;
Cursor cursor;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.add);
    // TODO Auto-generated method stub

    final EditText jobIdInput = (EditText) findViewById(R.id.jobText); 
    //final EditText address1Input = (EditText) findViewById(R.id.add1Text);  to be implemented

    /**************************************************
     * 
     *  Get text Input from Edit Text Fields
     * 
     ***************************************************/

    jobIdInput.addTextChangedListener(new TextWatcher(){

        @Override
        public void afterTextChanged(Editable id) {
            jobId = jobIdInput.getText().toString();

        }

        @Override
        public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                int arg3) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onTextChanged(CharSequence arg0, int arg1, int arg2,
                int arg3) {
            // TODO Auto-generated method stub

        }

    });

    /***************************************************
     * 
     *  initialise Database
     * 
     * 
     ***************************************************/
    mySQLiteAdapter = new SQLiteAdapter(this);

    /*****************************************************
     * Listen for Confirm button press
     ******************************************************/

    final Button confirm = (Button)findViewById(R.id.confirmButt);

    confirm.setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            mySQLiteAdapter.openToWrite();
            mySQLiteAdapter.insert(jobId);
            mySQLiteAdapter.close();
        }

    });

    /***********************************************************
     * write jobId into SQl in the above method for button press
     * 
     *************************************************************/     
}
}

Answer 1

正如@CornishDibley所说，我认为您需要从手机/模拟器中删除数据库。据我所知，有两种方法可以做到这一点：

转到管理应用程序＆gt;＆gt;选择你的应用＆gt;＆gt;点击清楚的数据
只需卸载您的应用程序，因为@CornishDibley已经说过

这应解决您的版本问题

提示：放置跟踪日志以调试程序并跟踪每个被执行的函数。看看你是否正在执行onCreat。如果没有，您的旧数据库文件仍然存在（据我所知）

Answer 2

管理得出答案;从实际上没有创建数据库的事实。不受版本更改影响，而且解决方案是在主数据库测试活动中初始化数据库而不是AddActivty !!

当然没有我直接进入另一个NullPointerException - 但至少现在处理它是一个不同的问题!!

column _id不存在 - 但我确信它确实存在

2 个答案: