我正在尝试将一个新活动作为Dialog Activity启动，将Intent放在另一个活动的按钮上。每当我尝试按下按钮时，活动就会关闭。
主要Activity.java
public class MainActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button ab = (Button) findViewById(R.id.button1);
ab.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent intent = new Intent(MainActivity.this, NewDialog.class);
startActivity(intent);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void side(View view){
android.support.v4.app.FragmentManager fm1 = getSupportFragmentManager();
NewDialog newdialog = new NewDialog();
newdialog.show(fm1, "SideDialog");
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
}
NewDialog.java
public class NewDialog extends DialogFragment{
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState){
final View view = inflater.inflate(R.layout.activity_new_dialog, container);
getDialog().requestWindowFeature(Window.FEATURE_NO_TITLE);
return view;
}
}
添加了Logcat：
05-29 22:37:36.472: D/dalvikvm(26806): Late-enabling CheckJNI
05-29 22:37:36.762: D/ActivityThread(26806): setTargetHeapUtilization:0.25
05-29 22:37:36.762: D/ActivityThread(26806): setTargetHeapIdealFree:8388608
05-29 22:37:36.762: D/ActivityThread(26806): setTargetHeapConcurrentStart:2097152
05-29 22:37:39.172: D/libEGL(26806): loaded /system/lib/egl/libEGL_adreno200.so
05-29 22:37:39.222: D/libEGL(26806): loaded /system/lib/egl/libGLESv1_CM_adreno200.so
05-29 22:37:39.322: D/libEGL(26806): loaded /system/lib/egl/libGLESv2_adreno200.so
05-29 22:37:39.362: I/Adreno200-EGL(26806): <qeglDrvAPI_eglInitialize:299>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_JB_REL_2.0.3.1_RB1.04.01.01.45.000_msm8625_JB_REL_2.0.3.1_Merge_release_AU (Merge)
05-29 22:37:39.362: I/Adreno200-EGL(26806): Build Date: 03/28/13 Thu
05-29 22:37:39.362: I/Adreno200-EGL(26806): Local Branch:
05-29 22:37:39.362: I/Adreno200-EGL(26806): Remote Branch: m/jb_rel_2.0.3.1
05-29 22:37:39.362: I/Adreno200-EGL(26806): Local Patches: NONE
05-29 22:37:39.362: I/Adreno200-EGL(26806): Reconstruct Branch: NOTHING
05-29 22:37:39.452: D/OpenGLRenderer(26806): Enabling debug mode 0
05-29 22:37:43.822: D/AndroidRuntime(26806): Shutting down VM
05-29 22:37:43.822: W/dalvikvm(26806): threadid=1: thread exiting with uncaught exception (group=0x40fd4438)
05-29 22:37:44.022: E/AndroidRuntime(26806): FATAL EXCEPTION: main
05-29 22:37:44.022: E/AndroidRuntime(26806): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.createdialog/com.example.createdialog.NewDialog}: java.lang.ClassCastException: com.example.createdialog.NewDialog cannot be cast to android.app.Activity
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2038)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2139)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread.access$700(ActivityThread.java:143)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1241)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.os.Handler.dispatchMessage(Handler.java:99)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.os.Looper.loop(Looper.java:137)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread.main(ActivityThread.java:4963)
05-29 22:37:44.022: E/AndroidRuntime(26806): at java.lang.reflect.Method.invokeNative(Native Method)
05-29 22:37:44.022: E/AndroidRuntime(26806): at java.lang.reflect.Method.invoke(Method.java:511)
05-29 22:37:44.022: E/AndroidRuntime(26806): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
05-29 22:37:44.022: E/AndroidRuntime(26806): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
05-29 22:37:44.022: E/AndroidRuntime(26806): at dalvik.system.NativeStart.main(Native Method)
05-29 22:37:44.022: E/AndroidRuntime(26806): Caused by: java.lang.ClassCastException: com.example.createdialog.NewDialog cannot be cast to android.app.Activity
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.Instrumentation.newActivity(Instrumentation.java:1068)
05-29 22:37:44.022: E/AndroidRuntime(26806): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2029)
05-29 22:37:44.022: E/AndroidRuntime(26806): ... 11 more
答案 0 :(得分：0)
如果没有logcat堆栈跟踪，我假设您的问题与变量范围（here is an example explanation on the topic）有关。
您需要做的是将您的按钮声明为类级别变量，因为它现在是一个方法变量，因此一旦您的onCreate方法执行完毕就不再存在。
public class MainActivity extends FragmentActivity {
private Button myButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myButton = (Button) findViewById(R.id.button1);
myButton.setOnClickListener(...);
...
}
}
答案 1 :(得分：0)
我可能在这里错了，但据我所知，你不能Intent传递DialogFragment，你应该通过Activity。这有什么错误：
Intent intent = new Intent(MainActivity.this, NewDialog.class);
startActivity(intent);
由于NewDialog被声明为DialogFragment而不是Activity子类。
如果你要做的是显示对话框，那么你应该这样做：
NewDialog dialog = NewDialog();
// use getSupportFragmentManager() if using support fragments instead of native fragments, or
// use getChildFragmentManager() if this code is inside a fragment rather than an activity
dialog.show(getFragmentManager(), "pass-any-string-here");