如何解决类强制转换异常 [英] How Can I Solve Class Cast Exception

问题描述

班级代码

Class code

package com.example.vetriselvanv.myapplication;
/**
 * Created by vetriselvan.v on 5/16/2015.
 */
public class DeviceDetails extends MainActivity {

    private String PhoneNumber;
    private String IMEI;
    private String BatteryLevel;


    public String getPhoneNumber() {
        return PhoneNumber;
    }
    public void setPhoneNumber(String aPhoneNumber) {
        PhoneNumber =aPhoneNumber ;
    }
    public String getIMEI() {

        return IMEI;
    }
    public void setIMEI(String aIMEI) {
        IMEI=aIMEI;
    }
    public String getBatteryLevel()
    {
        return  BatteryLevel;
    }
    public void setBatteryLevel(String aBatteryLevel)
    {
        BatteryLevel =aBatteryLevel;
    }

}

主要活动

package com.example.vetriselvanv.myapplication;



import android.content.Context;

import android.content.Intent ;

导入android.os.Bundle;

导入android.support.v7.app.ActionBarActivity;

导入android.telephony.TelephonyManager;

导入android.widget.EditText;

导入android.widget.Toast;





公共类MainActivity扩展ActionBarActivity {

字符串字符串，mPhoneNumber;

@Override

protected void onCreate（Bundle savedInstanceState）{< br $>
super.onCreate（savedInstanceState）;

setContentView（R.layout.activity_main）;

final DeviceDetails device =（DeviceDetails）getApplicationContext （）; // 这里

device.setIMEI（string）;

device.setBatteryLevel（mPho neNumber）;

final String IMEI = device.getIMEI（）;

final String Phone = device.getPhoneNumber（）;

Toast.makeText （getApplicationContext（），设备ID+ IMEI +\\\
Mobile编号+电话，Toast.LENGTH_LONG）。show（）;

意图i =新意图（getBaseContext（），DeviceDetails.class ）;

startActivity（i）;

Vetri（）;

Toast（）;

}

public void Vetri（）

{



TelephonyManager tm =（TelephonyManager）getSystemService（Context.TELEPHONY_SERVICE）;

string = tm.getDeviceId（）;

mPhoneNumber = tm.getLine1Number（）;

EditText et =（EditText）findViewById（R.id .editText）;

EditText ett =（EditText）findViewById（R.id.editText2）;

ett.setText（mPhoneNumber）;

et.setText（string）;







}

清单代码



< manifest xmlns：android =http://schemas.android.com/apk/res/android>

package =com.example.vetriselvanv.myapplication>



< application>

android：name =com.example。 vetriselvanv.myapplication.DeviceDetails

android：allowBackup =true

android：icon =@ mipmap / 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> < br $> b $ b



< activity android：name =。DeviceDetails&g t;

Main Activity
package com.example.vetriselvanv.myapplication;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.telephony.TelephonyManager;
import android.widget.EditText;
import android.widget.Toast;


public class MainActivity extends ActionBarActivity {
String string,mPhoneNumber;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final DeviceDetails device=(DeviceDetails)getApplicationContext();//here
device.setIMEI(string);
device.setBatteryLevel(mPhoneNumber);
final String IMEI=device.getIMEI();
final String Phone=device.getPhoneNumber();
Toast.makeText(getApplicationContext(),"Device ID"+IMEI+"\nMobile Number"+Phone, Toast.LENGTH_LONG).show();
Intent i = new Intent(getBaseContext(), DeviceDetails.class);
startActivity(i);
Vetri();
Toast();
}
public void Vetri()
{

TelephonyManager tm = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
string = tm.getDeviceId();
mPhoneNumber = tm.getLine1Number();
EditText et=(EditText)findViewById(R.id.editText);
EditText ett=(EditText)findViewById(R.id.editText2);
ett.setText(mPhoneNumber);
et.setText(string);



}
Manifest code

<manifest xmlns:android="http://schemas.android.com/apk/res/android">
package="com.example.vetriselvanv.myapplication" >

<application>
android:name="com.example.vetriselvanv.myapplication.DeviceDetails"
android:allowBackup="true"
android:icon="@mipmap/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">


<activity android:name=".DeviceDetails">

推荐答案

getApplicationContext [ ^ ]返回当前进程的单个全局Application对象的上下文。您不能随意将其转换为其他类类型。

getApplicationContext[^] returns the context of the single, global Application object of the current process. You cannot randomly cast that to a different class type.

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