相关疑难解决方法(0)

我正在尝试创建应用程序READ PHONE STATE以及何时更改手机状态以显示Toast当前状态.但是当我启动它时,应用程序意外停止.

我的课 :

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
import android.widget.TextView;

public class TelephonyDemo extends Activity {
    TextView textOut;
    TelephonyManager telephonyManager;
    PhoneStateListener listener;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // Get the UI
        textOut = (TextView) findViewById(R.id.textOut);

        // Get the telephony manager
        telephonyManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);

        // Create a new PhoneStateListener
        listener = new PhoneStateListener() {
            @Override
            public void …