我想在单击按钮时在 activity_main 中显示一个 fragmentTabHost。当我单击它时,它显示“不幸的是 FragTabHost 已停止”。下面是代码。请帮助我!!
主要 Activity
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button=(Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
TestFragment fragment=new TestFragment();
FragmentManager fragmentManager=fragment.getFragmentManager();
FragmentTransaction transaction=fragmentManager.beginTransaction();
transaction.replace(R.id.relative,fragment);
transaction.commit();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@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();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
Activity 主体
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
android:id="@+id/relative"
tools:context=".MainActivity">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/button"
android:text="TabHost"/>
</RelativeLayout>
测试 fragment
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_weight="0" />
<FrameLayout
android:id="@+id/realtabcontent"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"/>
<TabWidget
android:id="@android:id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0"
android:orientation="horizontal" />
</LinearLayout>
测试 fragment
package com.example.sabudaniel61.fragtabhost;
/**
* Created by Sabudaniel61 on 2015-09-30.
*/
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTabHost;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class TestFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
FragmentTabHost tabHost = new FragmentTabHost(getActivity());
inflater.inflate(R.layout.test_fragment, tabHost);
tabHost.setup(getActivity(),
getChildFragmentManager(), R.id.realtabcontent);
tabHost.addTab(tabHost.newTabSpec("simple")
.setIndicator("Simple"), DummySectionFragment.class, null);
tabHost.addTab(tabHost.newTabSpec("contacts")
.setIndicator("Contacts"), DummySectionFragment.class, null);
return tabHost;
}
/**
* A dummy fragment representing a section of the app,
* but that simply displays dummy text.
*/
public static class DummySectionFragment extends Fragment {
private static int count = 0;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_section_dummy,
container, false);
((TextView) rootView.findViewById(android.R.id.text1))
.setText("Dummy Section " + count++);
return rootView;
}
}
}
fragment_section_dummy
<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/text1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:textSize="24sp"
android:padding="32dp"
/>
日志:
09-30 00:43:18.676 28335-28335/com.example.sabudaniel61.fragtabhost E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.sabudaniel61.fragtabhost, PID: 28335
java.lang.NullPointerException: Attempt to invoke virtual method 'android.support.v4.app.FragmentTransaction android.support.v4.app.FragmentManager.beginTransaction()' on a null object reference
at com.example.sabudaniel61.fragtabhost.MainActivity$1.onClick(MainActivity.java:24)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
09-30 00:48:19.063 28335-28335/com.example.sabudaniel61.fragtabhost I/Process﹕ Sending signal. PID: 28335 SIG: 9
最佳答案
您在 MainActivity
的第 24 行收到 NullPointerException
。
替换
FragmentManager fragmentManager=fragment.getFragmentManager();
与
FragmentManager fragmentManager=this.getSupportFragmentManager();
在 MainActivity 中。
关于Android studio Fragment TabHost,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/32858085/