加入onClickListener时的Android应用程序崩溃 [英] App crashes when adding onClickListener Android
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问题描述
我不知道为什么,但我似乎无法弄清楚什么是错我的code。当我添加onclickListener应用程序崩溃。我真的需要帮助。此外,我看了看其他的线程,但我似乎无法找出什么我做错了。谢谢
在code是如下:
I don't know why but I can't seem to figure out what is wrong with my code. As soon as I add an onclickListener the app crashes. I really need help. Also I looked at other threads but I can't seem to find out what I'm doing wrong. Thanks The code is below:
package com.example.medrec;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.app.AlertDialog;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.Toast;
import android.os.Build;
public class MainActivity extends ActionBarActivity implements OnClickListener{
Button login;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
login = (Button)findViewById(R.id.w_login);
//Crashes when I add this line.
login.setOnClickListener(this);
}
@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;
}
@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.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
}
我activity_main.xml中
My activity_main.xml
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.medrec.MainActivity"
tools:ignore="MergeRootFrame" />
我fragment_main.xml
My fragment_main.xml
<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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.medrec.MainActivity$PlaceholderFragment" >
<EditText
android:id="@+id/w_number_edit_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView1"
android:layout_centerHorizontal="true"
android:layout_marginTop="21dp"
android:ems="10"
android:inputType="number" >
<requestFocus />
</EditText>
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="118dp"
android:text="@string/w_number" />
<Button
android:id="@+id/w_login"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/w_number_edit_text"
android:layout_centerHorizontal="true"
android:layout_marginTop="15dp"
android:text="@string/w_login_text" />
推荐答案
试试下面code: -
try below code:-
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
login = (Button)rootView.findViewById(R.id.w_login);
//Crashes when I add this line.
login.setOnClickListener(this);
return rootView;
}
}
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