android - 尝试导入示例项目，但每次导入都有以下错误 import name cannot be resolve

Question

我正在尝试学习 NFC 并在 http://www.framentos.com/en/android-tutorial/2012/07/31/write-hello-world-into-a-nfc-tag-with下载示例项目-一个/

我从文件菜单中选择了导入，然后将现有项目选择到工作区并选择相应的 zip 文件。

新项目出现在我的 Eclipse 工作区和那里的所有文件中，但在源文件中，每次导入时都会出现错误，提示无法解析导入名称，例如无法解析导入 java.io。

我有下面的源代码，但我假设它在 Eclipse 中有一些设置？

package com.framentos.hellonfc;
import java.io.IOException;
import java.io.UnsupportedEncodingException;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.FormatException;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.nfc.tech.NdefFormatable;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;


@SuppressLint({ "ParserError", "ParserError" })
public class MainActivity extends Activity{

NfcAdapter adapter;
PendingIntent pendingIntent;
IntentFilter writeTagFilters[];
boolean writeMode;
Tag mytag;
Context ctx;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    ctx=this;
    Button btnWrite = (Button) findViewById(R.id.button);
    final TextView message = (TextView)findViewById(R.id.edit_message);

    btnWrite.setOnClickListener(new View.OnClickListener()
    {
        @Override
        public void onClick(View v) {
            try {
                if(mytag==null){
                    Toast.makeText(ctx, ctx.getString(R.string.error_detected), Toast.LENGTH_LONG ).show();
                }else{
                    write(message.getText().toString(),mytag);
                    Toast.makeText(ctx, ctx.getString(R.string.ok_writing), Toast.LENGTH_LONG ).show();
                }
            } catch (IOException e) {
                Toast.makeText(ctx, ctx.getString(R.string.error_writing), Toast.LENGTH_LONG ).show();
                e.printStackTrace();
            } catch (FormatException e) {
                Toast.makeText(ctx, ctx.getString(R.string.error_writing) , Toast.LENGTH_LONG ).show();
                e.printStackTrace();
            }
        }
    });

    adapter = NfcAdapter.getDefaultAdapter(this);
    pendingIntent = PendingIntent.getActivity(this, 0, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
    IntentFilter tagDetected = new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED);
    tagDetected.addCategory(Intent.CATEGORY_DEFAULT);
    writeTagFilters = new IntentFilter[] { tagDetected };

}



private void write(String text, Tag tag) throws IOException, FormatException {

    NdefRecord[] records = { createRecord(text) };
    NdefMessage  message = new NdefMessage(records);
    // Get an instance of Ndef for the tag.
    Ndef ndef = Ndef.get(tag);
    // Enable I/O
    ndef.connect();
    // Write the message
    ndef.writeNdefMessage(message);
    // Close the connection
    ndef.close();
}



private NdefRecord createRecord(String text) throws UnsupportedEncodingException {
    String lang       = "en";
    byte[] textBytes  = text.getBytes();
    byte[] langBytes  = lang.getBytes("US-ASCII");
    int    langLength = langBytes.length;
    int    textLength = textBytes.length;
    byte[] payload    = new byte[1 + langLength + textLength];

    // set status byte (see NDEF spec for actual bits)
    payload[0] = (byte) langLength;

    // copy langbytes and textbytes into payload
    System.arraycopy(langBytes, 0, payload, 1,              langLength);
    System.arraycopy(textBytes, 0, payload, 1 + langLength, textLength);

    NdefRecord recordNFC = new NdefRecord(NdefRecord.TNF_WELL_KNOWN,  NdefRecord.RTD_TEXT,  new byte[0], payload);

    return recordNFC;
}


@Override
protected void onNewIntent(Intent intent){
    if(NfcAdapter.ACTION_TAG_DISCOVERED.equals(intent.getAction())){
        mytag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);    
        Toast.makeText(this, this.getString(R.string.ok_detection) + mytag.toString(), Toast.LENGTH_LONG ).show();
    }
}

@Override
public void onPause(){
    super.onPause();
    WriteModeOff();
}

@Override
public void onResume(){
    super.onResume();
    WriteModeOn();
}

private void WriteModeOn(){
    writeMode = true;
    adapter.enableForegroundDispatch(this, pendingIntent, writeTagFilters, null);
}

private void WriteModeOff(){
    writeMode = false;
    adapter.disableForegroundDispatch(this);
}


}