将txt文件读入二维数组强制退出

Question

首先我很抱歉我的英语不好。我想读取 txt 文件并进入二维数组。这段代码在java上成功运行。但android模拟器给出警告消息：“对不起！应用程序已意外停止。请重试”

我该如何解决这个问题？谢谢

这是我的代码：

package com.example.hocam;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class Konular extends ActionBarActivity {

  private ListView konuListe;
  private List<KonuBilgileri> konuBilgileri;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_konular);
    Bundle dersadi = getIntent().getExtras();
    String dersinadi= dersadi.getString("Ders");

   switch(dersinadi)  {
   case "Turkce": 
       KonuGetir turkce=new KonuGetir("turkce.txt");

       String[][] turkcekonular=turkce.getKonular();

      System.out.println(turkcekonular[0][0]);  // it is the problem and give error
       konuListe = (ListView) findViewById(R.id.konu_listesi);
        konuBilgileri = new ArrayList<KonuBilgileri>();
       konuBilgileri.add(new KonuBilgileri(turkcekonular[0][0],R.drawable.turkce, turkcekonular[0][1]));  // array is problem

        MyAdapter adapter = new MyAdapter(Konular.this, R.layout.custom_list_item, konuBilgileri);
       konuListe.setAdapter(adapter);

       break;

   }
}

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

}

 import java.io.File;
 import java.io.FileNotFoundException;
 import java.util.Scanner;

public class KonuGetir {
final int maxLines = 10100;
String[][] resultArray = new String[maxLines][];

public KonuGetir(String Ders){
      File file = new File(Ders);
        Scanner scanner;
        try {
            scanner = new Scanner(file,"utf-8");
             int linesCounter = 0;
                while (scanner.hasNextLine() && linesCounter < maxLines) {
                    resultArray[linesCounter] = scanner.nextLine().split("@");
                    linesCounter++;
                }
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

}
public String[][] getKonular()  {
    return resultArray;
}
}

日志文件：

> 09-04 16:18:22.262: E/AndroidRuntime(1164): FATAL EXCEPTION: main
09-04 16:18:22.262: E/AndroidRuntime(1164): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hocam/com.example.hocam.Konular}: java.lang.NullPointerException
09-04 16:18:22.262: E/AndroidRuntime(1164):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at android.os.Looper.loop(Looper.java:123)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at android.app.ActivityThread.main(ActivityThread.java:4627)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at java.lang.reflect.Method.invokeNative(Native Method)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at java.lang.reflect.Method.invoke(Method.java:521)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at dalvik.system.NativeStart.main(Native Method)
09-04 16:18:22.262: E/AndroidRuntime(1164): Caused by: java.lang.NullPointerException
09-04 16:18:22.262: E/AndroidRuntime(1164):     at com.example.hocam.Konular.onCreate(Konular.java:66)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-04 16:18:22.262: E/AndroidRuntime(1164):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
09-04 16:18:22.262: E/AndroidRuntime(1164):     ... 11 more
09-04 16:42:10.422: E/AndroidRuntime(1178): FATAL EXCEPTION: main
09-04 16:42:10.422: E/AndroidRuntime(1178): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hocam/com.example.hocam.Konular}: java.lang.NullPointerException
09-04 16:42:10.422: E/AndroidRuntime(1178):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at android.os.Looper.loop(Looper.java:123)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at android.app.ActivityThread.main(ActivityThread.java:4627)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at java.lang.reflect.Method.invokeNative(Native Method)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at java.lang.reflect.Method.invoke(Method.java:521)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at dalvik.system.NativeStart.main(Native Method)
09-04 16:42:10.422: E/AndroidRuntime(1178): Caused by: java.lang.NullPointerException
09-04 16:42:10.422: E/AndroidRuntime(1178):     at com.example.hocam.Konular.onCreate(Konular.java:66)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-04 16:42:10.422: E/AndroidRuntime(1178):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
09-04 16:42:10.422: E/AndroidRuntime(1178):     ... 11 more
09-04 16:43:28.802: E/AndroidRuntime(1207): FATAL EXCEPTION: main
09-04 16:43:28.802: E/AndroidRuntime(1207): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hocam/com.example.hocam.Konular}: java.lang.NullPointerException
09-04 16:43:28.802: E/AndroidRuntime(1207):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at android.os.Looper.loop(Looper.java:123)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at android.app.ActivityThread.main(ActivityThread.java:4627)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at java.lang.reflect.Method.invokeNative(Native Method)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at java.lang.reflect.Method.invoke(Method.java:521)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at dalvik.system.NativeStart.main(Native Method)
09-04 16:43:28.802: E/AndroidRuntime(1207): Caused by: java.lang.NullPointerException
09-04 16:43:28.802: E/AndroidRuntime(1207):     at com.example.hocam.Konular.onCreate(Konular.java:66)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-04 16:43:28.802: E/AndroidRuntime(1207):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
09-04 16:43:28.802: E/AndroidRuntime(1207):     ... 11 more

android 清单文件：

<uses-permission android:name="android.permission.INTERNET" />

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="21" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name=".YGS"
        android:label="@string/title_activity_ygs" >
    </activity>
    <activity
        android:name=".Konular"
        android:label="@string/title_activity_konular" >
    </activity>
    <activity
        android:name=".Video"
        android:screenOrientation="landscape"
        android:label="@string/title_activity_video" >

    </activity>
</application>

Answer 1

您正在使用以下代码：

  String[][] turkcekonular=turkce.getKonular();

  System.out.println(turkcekonular[0][0]); 

但是得到java.lang.NullPointerException。

这是因为getKonular() 返回一个初始化为10100 大小的数组，但是scanner 不包含任何行，所以scanner.hasNextLine() 为假。

这意味着turkcekonular[0] 为空，因为它从未设置过。 这意味着turkcekonular[0][0] 正在尝试访问一个空对象，所以抛出一个NullPointerException

你应该在尝试访问它之前检查对象是否为空。

 if(turkcekonular[0] != null)
      System.out.println(turkcekonular[0][0]); 

以及出现此问题的其他地方。

（你应该弄清楚为什么你的文件没有被读取。它是否命名正确并存在于指定的路径中？）