Android 通过活动中的onclicklistener切换片段
我有一个带有片段的应用程序,我想通过一个按钮操作的活动在它们之间切换。这是我的尝试。我怎么做Android 通过活动中的onclicklistener切换片段,android,button,android-activity,fragment,switching,Android,Button,Android Activity,Fragment,Switching,我有一个带有片段的应用程序,我想通过一个按钮操作的活动在它们之间切换。这是我的尝试。我怎么做 public class StartActivity extends Activity { public static Context appContext; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
public class StartActivity extends Activity {
public static Context appContext;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Fragment
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction =
fragmentManager.beginTransaction();
MeinFragment A_fragment = new MeinFragment();
fragmentTransaction.replace(android.R.id.content, A_fragment);
fragmentTransaction.commit();
ImageButton BTN1 = (ImageButton) findViewById(R.id.leftButton);
BTN1.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
SearchFragment A_fragment = new SearchFragment();
fragmentTransaction.replace(android.R.id.content, A_fragment);
}
});
}
}
我第二次尝试,但应用程序崩溃了
公共类StartActivity扩展活动{
公共静态语境
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
MeinFragment A_fragment = new MeinFragment();
fragmentTransaction.replace(android.R.id.content, A_fragment);
fragmentTransaction.commit();
//Fragments changing
ImageButton BTN1 = (ImageButton) findViewById(R.id.leftButton);
BTN1.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
SearchFragment B_fragment = new SearchFragment();
fragmentTransaction.replace(android.R.id.content, B_fragment);
fragmentTransaction.commit();
}
});
}
}
和logcat:
01-27 17:37:51.412:E/AndroidRuntime(3339):致命异常:主
01-27 17:37:51.412:E/AndroidRuntime(3339):java.lang.RuntimeException:无法启动活动组件信息{de.arvidg.exampleactionbartabs/de.arvidg.exampleactionbartabs.StartActivity}:java.lang.NullPointerException
01-27 17:37:51.412:E/AndroidRuntime(3339):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
01-27 17:37:51.412:E/AndroidRuntime(3339):位于android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
01-27 17:37:51.412:E/AndroidRuntime(3339):在android.app.ActivityThread.access$600(ActivityThread.java:141)
01-27 17:37:51.412:E/AndroidRuntime(3339):在android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
01-27 17:37:51.412:E/AndroidRuntime(3339):位于android.os.Handler.dispatchMessage(Handler.java:99)
01-27 17:37:51.412:E/AndroidRuntime(3339):在android.os.Looper.loop(Looper.java:137)
01-27 17:37:51.412:E/AndroidRuntime(3339):位于android.app.ActivityThread.main(ActivityThread.java:5103)
01-27 17:37:51.412:E/AndroidRuntime(3339):位于java.lang.reflect.Method.Invokenactive(本机方法)
01-27 17:37:51.412:E/AndroidRuntime(3339):在java.lang.reflect.Method.invoke(Method.java:525)
01-27 17:37:51.412:E/AndroidRuntime(3339):在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
01-27 17:37:51.412:E/AndroidRuntime(3339):位于com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
01-27 17:37:51.412:E/AndroidRuntime(3339):在dalvik.system.NativeStart.main(本机方法)
01-27 17:37:51.412:E/AndroidRuntime(3339):由以下原因引起:java.lang.NullPointerException
01-27 17:37:51.412:E/AndroidRuntime(3339):在de.arvidg.exampleactionbartabs.StartActivity.onCreate(StartActivity.java:52)
01-27 17:37:51.412:E/AndroidRuntime(3339):在android.app.Activity.performCreate(Activity.java:5133)
01-27 17:37:51.412:E/AndroidRuntime(3339):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
01-27 17:37:51.412:E/AndroidRuntime(3339):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
01-27 17:37:51.412:E/AndroidRuntime(3339):。。。还有11个
fragmentTransaction
.beginTransaction()
.replace(android.R.id.content, A_fragment)
.commit();
您需要开始事务并提交以完成操作。请参考javadoc了解FragmentTransaction。beginTransaction():
注意:片段事务只能在活动保存其状态之前创建/提交。如果尝试在Activity.onSaveInstanceState()之后(和在后续Activity.onStart或Activity.onResume()之前)提交事务,您将得到一个错误。这是因为框架负责保存状态中的当前片段,如果在保存状态后进行了更改,则这些更改将丢失。检查行号52,这就是问题的原因。第52行是注释:“//fragments changing”不是在onSaveInstanceState()中?代码正在onCreate()中调用replace()和commit()方法: