Java应用程序从文件中读取名称

时间:2014-04-07 11:08:01

标签: java android

我试图从.txt文件中读取一个名称和姓氏到java应用程序中,我尝试使用AssetManager的第一个方法,但是当我输入它时我的应用程序崩溃。

第二种方法是使用输入流,但我得到3个错误:

Description Resource    Path    Location    Type
ByteArrayOutputStream cannot be resolved to a type  MainActivity.java   /MyInfo/src/com/example/myinfo  line 64 Java Problem
ByteArrayOutputStream cannot be resolved to a type  MainActivity.java   /MyInfo/src/com/example/myinfo  line 64 Java Problem
dummytext cannot be resolved or is not a field  MainActivity.java   /MyInfo/src/com/example/myinfo  line 55 Java Problem

MainActivity.java

package com.example.myinfo;

import java.io.IOException;
import java.io.InputStream;

import android.os.Bundle;
import android.content.res.AssetManager;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    /*  
        TextView name = (TextView) findViewById(R.id.name);
        AssetManager assetManager = getAssets();



        InputStream input;
        try {

            input = assetManager.open("info.txt");

             int size = input.available();
             byte[] buffer = new byte[size];
             input.read(buffer);
             input.close();

             // byte buffer into a string
             String text = new String(buffer);

             nume.setText(text);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        */
        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }


        TextView dummytext = (TextView) findViewById(R.id.dummytext);
        dummytext.setText(readText());



    }

    private String readText() {
        InputStream inputStream = getResources().openRawResource(R.raw.dummytext);
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

        int i;
        try {
            i = inputStream.read();
            while(i!=-1){
                byteArrayOutputStream.write(i);
                i = inputStream.read();
            }
            inputStream.close();
        }catch (IOException e){
            e.printStackTrace();
        }
        return byteArrayOutputStream.toString();

        }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.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();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {



        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container,
                    false);

            return rootView;
        }
    }


}

我的XML是这样的:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.myinfo.MainActivity$PlaceholderFragment" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="87dp"
        android:text="Adauga Fisier" />

    <TextView
        android:id="@+id/dummytext"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/nume"
        android:layout_below="@+id/nume"
        android:layout_marginTop="29dp"
        android:text="Prenume"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignRight="@+id/button1"
        android:layout_marginRight="14dp"
        android:layout_marginTop="65dp"
        android:textAppearance="?android:attr/textAppearanceLarge" />

</RelativeLayout>

我不明白我做错了什么。 当我运行现在在注释中的代码时,我注意到我进入了Logcat NullPointerException。

logcat的:

04-07 10:06:11.298: I/dalvikvm(275): Could not find method android.content.pm.PackageManager.getActivityLogo, referenced from method android.support.v7.internal.widget.ActionBarView.<init>
04-07 10:06:11.298: W/dalvikvm(275): VFY: unable to resolve virtual method 318: Landroid/content/pm/PackageManager;.getActivityLogo (Landroid/content/ComponentName;)Landroid/graphics/drawable/Drawable;
04-07 10:06:11.298: D/dalvikvm(275): VFY: replacing opcode 0x6e at 0x008b
04-07 10:06:11.308: I/dalvikvm(275): Could not find method android.content.pm.ApplicationInfo.loadLogo, referenced from method android.support.v7.internal.widget.ActionBarView.<init>
04-07 10:06:11.308: W/dalvikvm(275): VFY: unable to resolve virtual method 314: Landroid/content/pm/ApplicationInfo;.loadLogo (Landroid/content/pm/PackageManager;)Landroid/graphics/drawable/Drawable;
04-07 10:06:11.308: D/dalvikvm(275): VFY: replacing opcode 0x6e at 0x0099
04-07 10:06:11.318: D/dalvikvm(275): VFY: dead code 0x008e-0092 in Landroid/support/v7/internal/widget/ActionBarView;.<init> (Landroid/content/Context;Landroid/util/AttributeSet;)V
04-07 10:06:11.318: D/dalvikvm(275): VFY: dead code 0x009c-00a0 in Landroid/support/v7/internal/widget/ActionBarView;.<init> (Landroid/content/Context;Landroid/util/AttributeSet;)V
04-07 10:06:11.488: D/AndroidRuntime(275): Shutting down VM
04-07 10:06:11.488: W/dalvikvm(275): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
04-07 10:06:11.498: E/AndroidRuntime(275): FATAL EXCEPTION: main
04-07 10:06:11.498: E/AndroidRuntime(275): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myinfo/com.example.myinfo.MainActivity}: java.lang.NullPointerException
04-07 10:06:11.498: E/AndroidRuntime(275):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
04-07 10:06:11.498: E/AndroidRuntime(275):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
04-07 10:06:11.498: E/AndroidRuntime(275):  at android.app.ActivityThread.access$2300(ActivityThread.java:125)
04-07 10:06:11.498: E/AndroidRuntime(275):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
04-07 10:06:11.498: E/AndroidRuntime(275):  at android.os.Handler.dispatchMessage(Handler.java:99)
04-07 10:06:11.498: E/AndroidRuntime(275):  at android.os.Looper.loop(Looper.java:123)
04-07 10:06:11.498: E/AndroidRuntime(275):  at android.app.ActivityThread.main(ActivityThread.java:4627)
04-07 10:06:11.498: E/AndroidRuntime(275):  at java.lang.reflect.Method.invokeNative(Native Method)
04-07 10:06:11.498: E/AndroidRuntime(275):  at java.lang.reflect.Method.invoke(Method.java:521)
04-07 10:06:11.498: E/AndroidRuntime(275):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-07 10:06:11.498: E/AndroidRuntime(275):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-07 10:06:11.498: E/AndroidRuntime(275):  at dalvik.system.NativeStart.main(Native Method)
04-07 10:06:11.498: E/AndroidRuntime(275): Caused by: java.lang.NullPointerException
04-07 10:06:11.498: E/AndroidRuntime(275):  at com.example.myinfo.MainActivity.onCreate(MainActivity.java:42)
04-07 10:06:11.498: E/AndroidRuntime(275):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-07 10:06:11.498: E/AndroidRuntime(275):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
04-07 10:06:11.498: E/AndroidRuntime(275):  ... 11 more
04-07 10:06:18.688: I/Process(275): Sending signal. PID: 275 SIG: 9

1 个答案:

答案 0 :(得分:0)

使用此代码

`InputStream input;
 AssetManager assetManager = getAssets();
  try {
   input = assetManager.open("helloworld.txt");

   int size = input.available();
   byte[] buffer = new byte[size];
   input.read(buffer);
   input.close();

   // byte buffer into a string
   String text = new String(buffer);

   dummytext.setText(text);
  } catch (IOException e) {
      e.printStackTrace();
  }
`

此代码从资产管理器打开文件的InputStream,从文件内容中获取大小,使用此大小分配字节缓冲区并在此缓冲区中读取文件,之后从缓冲区创建新字符串并将此字符串设置为textview