我怎样才能使ArrayLists成为微调器？

Question

Help me anything is wrong about the whole thing. I want to make a Spinner with the ArrayLists but it simply does not work! I think it has something to do with the 'protected void onCreate' part. I have tried so hard but I allways get the same error.

My Main Class:

package com.example.hvt;

import java.util.ArrayList;

import com.example.hvt.Klassenvertretung.Bezeichnung;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.Toast;



public class MainActivity extends ActionBarActivity implements OnItemSelectedListener {

public Spinner news, klassen;
public Button btnnews, btnklassen, btnzurueck1, btnzurueck2;
Bezeichnung bezeichnung;


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

    ArrayList<String> Bezeichnung = new ArrayList<String>();

    String listString = "";

    for (String s : Bezeichnung)
    {
        listString += s + "\t";
    }
    int listInt;
    listInt = Integer.parseInt(listString);

    Spinner klassen;
    ArrayAdapter<String> klassenadapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item);
    klassen = (Spinner) findViewById(R.id.klassenspinner);
    bezeichnung.Hinzufügen(bezeichnung);
    ArrayAdapter<String> klassen_adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, listInt);
    klassen_adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    klassen.setAdapter(klassenadapter);
    klassen.setSelection(0);
    klassen.setOnItemSelectedListener(this);

}


@Override
public void onItemSelected(AdapterView<?> parent, View v, int pos,
        long id) {
    if (pos == 1){
        setContentView(R.layout.activity_5aklassen);
    }
    if (pos <= 1 ){
        Toast.makeText(parent.getContext(), 
                "Deine Auswahl ist: " + parent.getItemAtPosition(pos).toString(),
                Toast.LENGTH_LONG).show();
    }
}

@Override
public void onNothingSelected(AdapterView<?> parent) {
    // TODO Auto-generated method stub

}
}

An Class in the same package(this Class picks information form the Internet| it should work because I have tested it in normal JAVA)

package com.example.hvt;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;


public class Vertretungsplan {

public Vertretungsplan(String woche)
{
    Woche = woche;
    Einlesen(woche);
}

public String Woche;

public List<Klassenvertretung> Klassen = new ArrayList<Klassenvertretung>();

private void Hinzufügen(Klassenvertretung neuesElement)
{
    Klassen.add(neuesElement);
}

private void Einlesen(String woche)
{
    try
    {
        for (int webseite = 1; webseite < 10000; webseite++)
        {
            Klassenvertretung klassenvertretung = new Klassenvertretung();

            String teilseite = "w000";
            if (webseite < 10)
                teilseite = teilseite + "0";
            teilseite = teilseite + webseite;

            Document doc =      Jsoup.connect("http://www.hh.shuttle.de/hh/gyhr/Vertretungsplan/Vertretungsplan_Internet/" + woche +    "/w/" + teilseite + ".htm").get();

            Element h2 = doc.select("h2").get(0);


            klassenvertretung.Bezeichnung = h2.text();

            Element table = doc.select("table").get(1);
            Element[] elemente = table.select("tr").toArray(new Element[0]);
            for (int i = 1; i < elemente.length; i++)
            {
                Element[] tds = elemente[i].select("td").toArray(new Element[0]);

                Vertretung vertretung = new Vertretung();
                vertretung.Klasse = tds[0].text();
                vertretung.Stunde = tds[1].text();
                vertretung.Art = tds[2].text();
                vertretung.Fach = tds[3].text();
                vertretung.Raum = tds[4].text();
                vertretung.stattFach = tds[5].text();
                vertretung.stattRaum = tds[6].text();
                vertretung.Informationen = tds[7].text();
                klassenvertretung.Hinzufügen(vertretung);
            }

            Hinzufügen(klassenvertretung);
        }
    }
    catch (IOException io)
    {

    }
    finally
    {
    }
}
}

Another Class in the same package(this code should combine all the info too two ArrayLists (tested it in normal JAVA as well so there shouldn't be a mistake))

package com.example.hvt;

import java.util.ArrayList;
import java.util.List;



public class Klassenvertretung
{   
public String Bezeichnung;

public static class Bezeichnung {
    public List<Bezeichnung> Bezeichnung = new ArrayList<Bezeichnung>();
    public void Hinzufügen(Bezeichnung neuesElement)
    {

        Bezeichnung.add(neuesElement);
    }


}

public List<Vertretung> Vertretungen = new ArrayList<Vertretung>();

public void Hinzufügen(Vertretung neuesElement)
{
    Vertretungen.add(neuesElement);
}
}

My last Class: (as you can see this is just a class where I defined some Object(they belong to the Class above))

package com.example.hvt;


public class Vertretung
{
public String Klasse;
public String Stunde;
public String Art;
public String Fach;
public String Raum;
public String stattFach;
public String stattRaum;
public String Informationen;
}

The Chat-Log:

11-15 00:26:26.160: I/dalvikvm(714): Could not find method android.view.ViewGroup.onNestedScrollAccepted, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.onNestedScrollAccepted
11-15 00:26:26.160: W/dalvikvm(714): VFY: unable to resolve virtual method 11377: Landroid/view/ViewGroup;.onNestedScrollAccepted (Landroid/view/View;Landroid/view/View;I)V
11-15 00:26:26.160: D/dalvikvm(714): VFY: replacing opcode 0x6f at 0x0000
11-15 00:26:26.160: I/dalvikvm(714): Could not find method android.view.ViewGroup.onStopNestedScroll, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.onStopNestedScroll
11-15 00:26:26.160: W/dalvikvm(714): VFY: unable to resolve virtual method 11383: Landroid/view/ViewGroup;.onStopNestedScroll (Landroid/view/View;)V
11-15 00:26:26.160: D/dalvikvm(714): VFY: replacing opcode 0x6f at 0x0000
11-15 00:26:26.170: I/dalvikvm(714): Could not find method android.support.v7.internal.widget.ActionBarOverlayLayout.stopNestedScroll, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.setHideOnContentScrollEnabled
11-15 00:26:26.170: W/dalvikvm(714): VFY: unable to resolve virtual method 8956: Landroid/support/v7/internal/widget/ActionBarOverlayLayout;.stopNestedScroll ()V
11-15 00:26:26.170: D/dalvikvm(714): VFY: replacing opcode 0x6e at 0x000e
11-15 00:26:26.190: I/dalvikvm(714): Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.internal.widget.TintTypedArray.getChangingConfigurations
11-15 00:26:26.190: W/dalvikvm(714): VFY: unable to resolve virtual method 364: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
11-15 00:26:26.190: D/dalvikvm(714): VFY: replacing opcode 0x6e at 0x0002
11-15 00:26:26.190: I/dalvikvm(714): Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.internal.widget.TintTypedArray.getType
11-15 00:26:26.190: W/dalvikvm(714): VFY: unable to resolve virtual method 386: Landroid/content/res/TypedArray;.getType (I)I
11-15 00:26:26.190: D/dalvikvm(714): VFY: replacing opcode 0x6e at 0x0002
11-15 00:26:26.320: D/AndroidRuntime(714): Shutting down VM
11-15 00:26:26.320: W/dalvikvm(714): threadid=1: thread exiting with uncaught exception (group=0xb1a90d70)
11-15 00:26:26.330: E/AndroidRuntime(714): FATAL EXCEPTION: main
11-15 00:26:26.330: E/AndroidRuntime(714): Process: com.example.hvt, PID: 714
11-15 00:26:26.330: E/AndroidRuntime(714): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hvt/com.example.hvt.MainActivity}: java.lang.NumberFormatException: Invalid int: ""
11-15 00:26:26.330: E/AndroidRuntime(714):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2197)
11-15 00:26:26.330: E/AndroidRuntime(714):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2258)
11-15 00:26:26.330: E/AndroidRuntime(714):  at android.app.ActivityThread.access$800(ActivityThread.java:138)
11-15 00:26:26.330: E/AndroidRuntime(714):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1209)
11-15 00:26:26.330: E/AndroidRuntime(714):  at android.os.Handler.dispatchMessage(Handler.java:102)
11-15 00:26:26.330: E/AndroidRuntime(714):  at android.os.Looper.loop(Looper.java:136)
11-15 00:26:26.330: E/AndroidRuntime(714):  at android.app.ActivityThread.main(ActivityThread.java:5026)
11-15 00:26:26.330: E/AndroidRuntime(714):  at java.lang.reflect.Method.invokeNative(Native Method)
11-15 00:26:26.330: E/AndroidRuntime(714):  at java.lang.reflect.Method.invoke(Method.java:515)
11-15 00:26:26.330: E/AndroidRuntime(714):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
11-15 00:26:26.330: E/AndroidRuntime(714):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
11-15 00:26:26.330: E/AndroidRuntime(714):  at dalvik.system.NativeStart.main(Native Method)
11-15 00:26:26.330: E/AndroidRuntime(714): Caused by: java.lang.NumberFormatException: Invalid int: ""
11-15 00:26:26.330: E/AndroidRuntime(714):  at java.lang.Integer.invalidInt(Integer.java:137)
11-15 00:26:26.330: E/AndroidRuntime(714):  at java.lang.Integer.parseInt(Integer.java:358)
11-15 00:26:26.330: E/AndroidRuntime(714):  at java.lang.Integer.parseInt(Integer.java:331)
11-15 00:26:26.330: E/AndroidRuntime(714):  at com.example.hvt.MainActivity.onCreate(MainActivity.java:39)
11-15 00:26:26.330: E/AndroidRuntime(714):  at android.app.Activity.performCreate(Activity.java:5242)
11-15 00:26:26.330: E/AndroidRuntime(714):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-15 00:26:26.330: E/AndroidRuntime(714):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2161)
11-15 00:26:26.330: E/AndroidRuntime(714):  ... 11 more
11-15 00:26:29.320: I/Process(714): Sending signal. PID: 714 SIG: 9
11-15 00:26:38.220: I/dalvikvm(803): Could not find method android.view.ViewGroup.onNestedScrollAccepted, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.onNestedScrollAccepted
11-15 00:26:38.220: W/dalvikvm(803): VFY: unable to resolve virtual method 11377: Landroid/view/ViewGroup;.onNestedScrollAccepted (Landroid/view/View;Landroid/view/View;I)V
11-15 00:26:38.220: D/dalvikvm(803): VFY: replacing opcode 0x6f at 0x0000
11-15 00:26:38.220: I/dalvikvm(803): Could not find method android.view.ViewGroup.onStopNestedScroll, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.onStopNestedScroll
11-15 00:26:38.220: W/dalvikvm(803): VFY: unable to resolve virtual method 11383: Landroid/view/ViewGroup;.onStopNestedScroll (Landroid/view/View;)V
11-15 00:26:38.230: D/dalvikvm(803): VFY: replacing opcode 0x6f at 0x0000
11-15 00:26:38.250: I/dalvikvm(803): Could not find method android.support.v7.internal.widget.ActionBarOverlayLayout.stopNestedScroll, referenced from method android.support.v7.internal.widget.ActionBarOverlayLayout.setHideOnContentScrollEnabled
11-15 00:26:38.250: W/dalvikvm(803): VFY: unable to resolve virtual method 8956: Landroid/support/v7/internal/widget/ActionBarOverlayLayout;.stopNestedScroll ()V
11-15 00:26:38.250: D/dalvikvm(803): VFY: replacing opcode 0x6e at 0x000e
11-15 00:26:38.270: I/dalvikvm(803): Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.internal.widget.TintTypedArray.getChangingConfigurations
11-15 00:26:38.270: W/dalvikvm(803): VFY: unable to resolve virtual method 364: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
11-15 00:26:38.270: D/dalvikvm(803): VFY: replacing opcode 0x6e at 0x0002
11-15 00:26:38.280: I/dalvikvm(803): Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.internal.widget.TintTypedArray.getType
11-15 00:26:38.280: W/dalvikvm(803): VFY: unable to resolve virtual method 386: Landroid/content/res/TypedArray;.getType (I)I
11-15 00:26:38.280: D/dalvikvm(803): VFY: replacing opcode 0x6e at 0x0002
11-15 00:26:38.400: D/AndroidRuntime(803): Shutting down VM
11-15 00:26:38.400: W/dalvikvm(803): threadid=1: thread exiting with uncaught exception (group=0xb1a90d70)
11-15 00:26:38.410: E/AndroidRuntime(803): FATAL EXCEPTION: main
11-15 00:26:38.410: E/AndroidRuntime(803): Process: com.example.hvt, PID: 803
11-15 00:26:38.410: E/AndroidRuntime(803): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hvt/com.example.hvt.MainActivity}: java.lang.NumberFormatException: Invalid int: ""
11-15 00:26:38.410: E/AndroidRuntime(803):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2197)
11-15 00:26:38.410: E/AndroidRuntime(803):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2258)
11-15 00:26:38.410: E/AndroidRuntime(803):  at android.app.ActivityThread.access$800(ActivityThread.java:138)
11-15 00:26:38.410: E/AndroidRuntime(803):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1209)
11-15 00:26:38.410: E/AndroidRuntime(803):  at android.os.Handler.dispatchMessage(Handler.java:102)
11-15 00:26:38.410: E/AndroidRuntime(803):  at android.os.Looper.loop(Looper.java:136)
11-15 00:26:38.410: E/AndroidRuntime(803):  at android.app.ActivityThread.main(ActivityThread.java:5026)
11-15 00:26:38.410: E/AndroidRuntime(803):  at java.lang.reflect.Method.invokeNative(Native Method)
11-15 00:26:38.410: E/AndroidRuntime(803):  at java.lang.reflect.Method.invoke(Method.java:515)
11-15 00:26:38.410: E/AndroidRuntime(803):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
11-15 00:26:38.410: E/AndroidRuntime(803):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
11-15 00:26:38.410: E/AndroidRuntime(803):  at dalvik.system.NativeStart.main(Native Method)
11-15 00:26:38.410: E/AndroidRuntime(803): Caused by: java.lang.NumberFormatException: Invalid int: ""
11-15 00:26:38.410: E/AndroidRuntime(803):  at java.lang.Integer.invalidInt(Integer.java:137)
11-15 00:26:38.410: E/AndroidRuntime(803):  at java.lang.Integer.parseInt(Integer.java:358)
11-15 00:26:38.410: E/AndroidRuntime(803):  at java.lang.Integer.parseInt(Integer.java:331)
11-15 00:26:38.410: E/AndroidRuntime(803):  at com.example.hvt.MainActivity.onCreate(MainActivity.java:39)
11-15 00:26:38.410: E/AndroidRuntime(803):  at android.app.Activity.performCreate(Activity.java:5242)
11-15 00:26:38.410: E/AndroidRuntime(803):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-15 00:26:38.410: E/AndroidRuntime(803):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2161)
11-15 00:26:38.410: E/AndroidRuntime(803):  ... 11 more

Answer 1

the error is bcz of "nothing there to parse!!"

you are creating the ArrayList but not assaigning or adding any values to List at all..!! your List is empty when it reaches the for loop: so it will return runtime exception as the Logcat shows.!

 ArrayList<String> Bezeichnung = new ArrayList<String>();

// populate your List before using it, otherwise it is null/"";
// need some statements like    
// Bezeichnung.add("string1");
// Bezeichnung.add("string1");

    String listString = "";


    for (String s : Bezeichnung)
    {
        listString += s + "\t";
    }

also have some suggestions for you,

you have to follow Java Naming Conventions to avoid mistakes by naming conflict! make sure you named them correct before running, it may cause generating some unexpected results, which you may not figure out easily!