英文:
why I can not use create method out side a function in AppCompatActivity
问题
以下是翻译好的内容：
当我像这样编写代码时，我的应用在启动时崩溃：
public class MainActivity extends AppCompatActivity {
MediaPlayer mplayer= MediaPlayer.create(this,R.raw.song);
public void playMusic(View view){
mplayer.start();
}
public void pauseMusic(View view){
mplayer.pause();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
但是当我像这样编写上面的代码时，它完美地工作：
public class MainActivity extends AppCompatActivity {
MediaPlayer mplayer;
public void playMusic(View view){
mplayer= MediaPlayer.create(this,R.raw.song);
mplayer.start();
}
public void pauseMusic(View view){
mplayer.pause();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
请问有人能告诉我第一个代码有什么问题吗？
谢谢
英文:
My app is crashing when I launch when I write code like this
public class MainActivity extends AppCompatActivity {
MediaPlayer mplayer= MediaPlayer.create(this,R.raw.song);
public void playMusic(View view){
mplayer.start();
}
public void pauseMusic(View view){
mplayer.pause();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
but when I write above code like this then it's working perfectly fine
public class MainActivity extends AppCompatActivity {
MediaPlayer mplayer;
public void playMusic(View view){
mplayer= MediaPlayer.create(this,R.raw.song);
mplayer.start();
}
public void pauseMusic(View view){
mplayer.pause();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
please anybody tell me what is wrong with first code
Thanks
答案1
得分: 0
因为玩家必须在上下文不为空的情况下进行初始化。也就是说，在上面的代码中，player 中的 context == null。因此，应用程序崩溃。
英文:
because the player must be initialized at the moment when the context is not empty. That is, in the upper code, context == null in player. Therefore, the application crashes.
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