Question

我能够通过模拟器成功运行我的应用程序。但突然出现了一堆错误，所以现在我无法启动它。有致命错误。这是LogCat输出：

 08-26 12:14:27.937    2112-2112/com.joudi.myapplication D/AndroidRuntime﹕ Shutting down VM
08-26 12:14:27.938    2112-2112/com.joudi.myapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.joudi.myapplication, PID: 2112
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.joudi.myapplication/com.joudi.myapplication.MainActivity}: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
            at android.app.ActivityThread.-wrap11(ActivityThread.java)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:148)
            at android.app.ActivityThread.main(ActivityThread.java:5417)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
     Caused by: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
            at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
            at java.util.ArrayList.get(ArrayList.java:308)
            at com.joudi.myapplication.MainActivity.onCreate(MainActivity.java:29)
            at android.app.Activity.performCreate(Activity.java:6237)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
            at android.app.ActivityThread.-wrap11(ActivityThread.java)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:148)
            at android.app.ActivityThread.main(ActivityThread.java:5417)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

我不知道要修复“IndexOutOfBoundsException：索引0无效，大小为0”错误。这是我的MainActicity.java文件代码：

import android.graphics.Canvas;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;

import com.joudi.myapplication.data.NoteItem;
import com.joudi.myapplication.data.NotesDataSource;

import java.util.List;

public class MainActivity extends AppCompatActivity {

    private NotesDataSource datasource;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        datasource = new NotesDataSource(this);
        List<NoteItem> notes= datasource.findAll();
        NoteItem note = notes.get(0);
        note.setText("Updated!");
        datasource.update(note);

        notes= datasource.findAll();
        note= notes.get(0);

        Log.i("NOTES", note.getKey());
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

Answer 1

外观datasource.findAll();看起来返回一个空列表。 notes.get(0);抛出异常。

您应该检查列表的大小是否大于0。

 if (notes.size() >0){
    NoteItem note = notes.get(0);

    note.setText("Updated!");
    datasource.update(note);
 }

AndroidStudio-致命错误：IndexOutOfBoundsException：索引0无效，大小为0

1 个答案: