代码不起作用

============问题描述============

我想运行一个获得手机通讯录联系人信息的apk，代码如下

  MainActivity.java：


package com.example.getphonenumber;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;


public class MainActivity extends ActionBarActivity {

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


    @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);
    }
    
  
  
}




Activity01.java：


package com.example.getphonenumber;

import android.app.Activity;
import android.content.ContentResolver;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.provider.ContactsContract.PhoneLookup;
import android.widget.TextView;

public class Activity01 extends Activity{
private int numberFieldColumnIndex;
private String contact;

public void onCreate(Bundle savedInstanceState){
TextView tv=new TextView(this);
String string="";
super.onCreate(savedInstanceState);
ContentResolver cr=getContentResolver();
Cursor cursor=cr.query(ContactsContract.Contacts.CONTENT_URI,null,null,null,null);
while(cursor.moveToNext())
{int nameFieldColumnIndex=cursor.getColumnIndex(PhoneLookup.DISPLAY_NAME);
String number=cursor.getString(numberFieldColumnIndex);
string +=(contact+":"+number+"\n");



}
cursor.close();
tv.setText(string);
setContentView(tv);
}

}



getphonenumber mainfest：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.getphonenumber"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="8" />
<uses-permission
            android:name="android.permission.READ_CONTACTS">
            
        </uses-permission>
    <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>
        
    </application>

</manifest>


activity_main.xml:

<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.getphonenumber.MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

</RelativeLayout>




但我运行出来的只有hello world

============解决方案1============

<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>

这里的MainActivity改成你的Activity01吧

============解决方案2============

……发成 code格式 好看点额，