Java 从 MainActvity 中的 onCreate() 启动另一个活动？
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Start Another Activity from onCreate() in MainActvity?
提问by Lethal Left Eye
The problem I am having is that the onCreate() method within my MainActivity cannot seem to start another activity.
我遇到的问题是 MainActivity 中的 onCreate() 方法似乎无法启动另一个活动。
I have code working so that when I click a button, my "AboutActivity" is started. However, I want to make it so that "AboutActivity" is started as soon as onCreate() in the MainActivity finishes.
我有代码工作，所以当我点击一个按钮时，我的“AboutActivity”就会启动。但是，我想让“关于活动”在 MainActivity 中的 onCreate() 完成后立即启动。
The program gets caught up at a blank screen when I run it while trying to start the "AboutActivity" from onCreate().
当我尝试从 onCreate() 启动“AboutActivity”时运行该程序时，该程序陷入空白屏幕。
The code posted is a simplified version of the problem. In essence, it is what I am trying to do.
发布的代码是问题的简化版本。从本质上讲，这就是我想要做的。
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Fire the intent that launches the "About" screen.
Intent aboutScreen = new Intent(getBaseContext(), AboutActivity.class);
this.startActivity(aboutScreen);
}
Code for the AboutActivity class:
AboutActivity 类的代码：
public class AboutActivity extends MainActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_about);
}
@Override
public void onPause() {
super.onPause();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
return super.onCreateOptionsMenu(menu);
}
}
The LogCat messages are:
LogCat 消息是：
11-16 16:33:47.335: D/dalvikvm(1702): GC_FOR_ALLOC freed 65K, 7% free 2692K/2876K, paused 70ms, total 72ms
11-16 16:33:47.335: I/dalvikvm-heap(1702): Grow heap (frag case) to 3.347MB for 635812-byte allocation
11-16 16:33:47.435: D/dalvikvm(1702): GC_FOR_ALLOC freed 2K, 6% free 3310K/3500K, paused 98ms, total 98ms
11-16 16:33:47.715: D/dalvikvm(1702): GC_FOR_ALLOC freed 20K, 4% free 3469K/3608K, paused 28ms, total 29ms
11-16 16:33:47.735: I/dalvikvm-heap(1702): Grow heap (frag case) to 5.478MB for 2073616-byte allocation
11-16 16:33:47.845: D/dalvikvm(1702): GC_FOR_ALLOC freed 1K, 3% free 5493K/5636K, paused 112ms, total 112ms
11-16 16:33:48.175: I/Choreographer(1702): Skipped 36 frames! The application may be doing too much work on its main thread.
11-16 16:33:48.465: D/libEGL(1702): loaded /system/lib/egl/libEGL_emulation.so
11-16 16:33:48.555: D/(1702): HostConnection::get() New Host Connection established 0x2a210280, tid 1702
11-16 16:33:48.604: D/libEGL(1702): loaded /system/lib/egl/libGLESv1_CM_emulation.so
11-16 16:33:48.615: D/libEGL(1702): loaded /system/lib/egl/libGLESv2_emulation.so
11-16 16:33:48.715: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:33:48.725: D/OpenGLRenderer(1702): Enabling debug mode 0
11-16 16:33:51.794: D/dalvikvm(1702): GC_FOR_ALLOC freed 139K, 4% free 6352K/6608K, paused 38ms, total 46ms
11-16 16:33:53.135: D/dalvikvm(1702): GREF has increased to 201
11-16 16:33:55.315: D/dalvikvm(1702): GC_FOR_ALLOC freed 219K, 5% free 7420K/7756K, paused 58ms, total 64ms
11-16 16:34:00.825: D/dalvikvm(1702): GC_FOR_ALLOC freed 281K, 5% free 8778K/9176K, paused 131ms, total 133ms
11-16 16:34:00.955: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:01.405: I/Choreographer(1702): Skipped 31 frames! The application may be doing too much work on its main thread.
11-16 16:34:01.635: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:02.295: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:03.026: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:03.625: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:04.246: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:04.875: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:05.557: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:06.206: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:06.675: D/dalvikvm(1702): GREF has increased to 301
11-16 16:34:06.816: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:07.458: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:07.978: I/Choreographer(1702): Skipped 30 frames! The application may be doing too much work on its main thread.
11-16 16:34:08.296: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:08.975: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:09.686: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:10.315: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:10.945: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:13.094: D/dalvikvm(1702): GC_FOR_ALLOC freed 367K, 5% free 10460K/10944K, paused 124ms, total 128ms
11-16 16:34:16.446: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:16.965: I/Choreographer(1702): Skipped 30 frames! The application may be doing too much work on its main thread.
11-16 16:34:17.125: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:17.625: I/Choreographer(1702): Skipped 30 frames! The application may be doing too much work on its main thread.
11-16 16:34:17.827: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:18.355: I/Choreographer(1702): Skipped 32 frames! The application may be doing too much work on its main thread.
11-16 16:34:18.555: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:19.145: I/Choreographer(1702): Skipped 34 frames! The application may be doing too much work on its main thread.
11-16 16:34:19.358: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:20.103: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:20.615: I/Choreographer(1702): Skipped 34 frames! The application may be doing too much work on its main thread.
11-16 16:34:20.880: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:22.825: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:23.445: I/Choreographer(1702): Skipped 35 frames! The application may be doing too much work on its main thread.
11-16 16:34:23.675: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:24.195: D/dalvikvm(1702): GC_FOR_ALLOC freed 381K, 4% free 12129K/12628K, paused 289ms, total 291ms
11-16 16:34:24.355: I/Choreographer(1702): Skipped 40 frames! The application may be doing too much work on its main thread.
11-16 16:34:24.585: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:25.215: I/Choreographer(1702): Skipped 36 frames! The application may be doing too much work on its main thread.
11-16 16:34:25.496: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:26.025: I/Choreographer(1702): Skipped 30 frames! The application may be doing too much work on its main thread.
11-16 16:34:26.235: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:26.735: D/dalvikvm(1702): GREF has increased to 401
11-16 16:34:26.795: I/Choreographer(1702): Skipped 32 frames! The application may be doing too much work on its main thread.
11-16 16:34:27.006: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:29.516: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:30.075: I/Choreographer(1702): Skipped 37 frames! The application may be doing too much work on its main thread.
11-16 16:34:30.305: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:30.825: I/Choreographer(1702): Skipped 31 frames! The application may be doing too much work on its main thread.
11-16 16:34:31.046: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:31.595: I/Choreographer(1702): Skipped 32 frames! The application may be doing too much work on its main thread.
11-16 16:34:31.816: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:32.385: I/Choreographer(1702): Skipped 34 frames! The application may be doing too much work on its main thread.
11-16 16:34:32.615: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:33.145: I/Choreographer(1702): Skipped 31 frames! The application may be doing too much work on its main thread.
11-16 16:34:33.365: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:37.115: D/dalvikvm(1702): GC_FOR_ALLOC freed 392K, 4% free 13787K/14296K, paused 164ms, total 167ms
11-16 16:34:38.345: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:45.285: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:49.475: I/Choreographer(1702): Skipped 67 frames! The application may be doing too much work on its main thread.
If I leave the application running on my AVD, the LogCat just keeps looping this section of the log:
如果我让应用程序在我的 AVD 上运行，LogCat 只会继续循环日志的这一部分：
11-16 16:34:31.046: W/EGL_emulation(1702): eglSurfaceAttrib not implemented
11-16 16:34:31.595: I/Choreographer(1702): Skipped 32 frames! The application may be doing too much work on its main thread.
I have no idea how to solve this issue. Please help!
我不知道如何解决这个问题。请帮忙！
采纳答案by Melquiades
Your AboutActivity class...
你的 AboutActivity 类...
public class AboutActivity extends MainActivity {
Please change it to:
请将其更改为：
public class AboutActivity extends Activity {
and as others noted, when constructing your intent, use this, or MainActivity.this.
正如其他人所指出的，在构建您的意图时，请使用 this 或 MainActivity.this。
回答by salrawaf
Try this instead:
试试这个：
Intent aboutScreen = new Intent(MainActivity.this, AboutActivity.class);
this.startActivity(aboutScreen);
回答by Kashif Nazar
Try passing thisinstead of getBaseContext()to the intent.
尝试传递this而不是传递getBaseContext()到意图。
public class MainActivity extends Activity {
公共类 MainActivity 扩展 Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Fire the intent that launches the "About" screen.
Intent aboutScreen = new Intent(this, AboutActivity.class);
this.startActivity(aboutScreen);
}
回答by Lethal Left Eye
I just realized what the problem is.
我刚刚意识到问题是什么。
The issue is that the AboutActivity is causing the intent to fire repeatedly. The first line in the AboutActivity's onCreate() is super.onCreate(savedInstanceState). This means that application control will go back to the MainActivity's onCreate() where the intent will then be fired again. Therefore, I seem to have caused an infinite loop of intent calling.
问题是 AboutActivity 导致意图反复触发。AboutActivity 的 onCreate() 中的第一行是 super.onCreate(savedInstanceState)。这意味着应用程序控制将返回到 MainActivity 的 onCreate() ，然后再次触发意图。因此，我似乎导致了意图调用的无限循环。
I will post the solution if I find it.
如果我找到它，我会发布解决方案。
回答by Jigar Pandya
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Fire the intent that launches the "About" screen.
Intent i= new Intent(this, AboutActivity.class);
startActivity(i);
