无法启动活动的Android模拟器
[英]Unable to start activity Android Emulator
问题描述
I'm new to Android Programming. 
我是Android编程的新手。 I'm following the guide on Android Developers to get started with Android. 我正在遵循Android开发人员指南来开始使用Android。 When trying to run simple Formular on the Emulator, the emulator shows 尝试在模拟器上运行简单的Formular时，模拟器显示
"Unfortunately, My First App has stopped.",
where MyFormular is name of the App. 其中MyFormular是应用程序的名称。 The Problem is that I made new layout from layout resource file and tried to connect to the new loyout fror here 问题是我从布局资源文件制作了新布局，并尝试在此处连接到新的loyout fror
setContentView(R.layout.form_layout (the new layout is form_layout)
the new layout 新布局
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="5">
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Please submit your details"
android:id="@+id/textView"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="46dp" />
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="textPersonName"
android:text="Name"
android:ems="10"
android:id="@+id/editText"
android:layout_marginTop="46dp"
android:layout_below="@+id/textView"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:hint="Name" />
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="textEmailAddress"
android:ems="10"
android:id="@+id/editText2"
android:layout_centerVertical="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="46dp"
android:hint="Email" />
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="textPassword"
android:ems="10"
android:id="@+id/editText3"
android:layout_below="@+id/editText2"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="46dp"
android:hint="Password" />
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="textPassword"
android:ems="10"
android:id="@+id/editText4"
android:layout_below="@+id/editText3"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="46dp"
android:hint="Confirm Password" />
</RelativeLayout>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="5">
<ImageView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/imageView"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="36dp"
android:src="@mipmap/ic_launcher" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Terms & Conditions"
android:id="@+id/textView2"
android:layout_below="@+id/imageView"
android:layout_centerHorizontal="true"
android:layout_marginTop="46dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceSmall"
android:text="A Terms and Conditions can be used for both your "
android:id="@+id/textView3"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="10dp" />
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="I agree"
android:id="@+id/checkBox"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginLeft="38dp"
android:layout_marginStart="38dp"
android:layout_marginBottom="38dp"
android:checked="false"
android:layout_marginRight="46dp" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Can't wait!Sign me up!"
android:id="@+id/button"
android:layout_alignTop="@+id/checkBox"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_marginRight="85dp"
android:layout_marginEnd="75dp" />
</RelativeLayout>
</LinearLayout>
MainFormular.java MainFormular.java
package com.example.melisa.myformular;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
public class MainFormular extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.form_layout);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById (R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
@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_formular, 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);
}
}
at android.app.Activity.performCreate (activity_main_formular 在android.app.Activity.performCreate（activity_main_formular
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="@layout/content_main_formular" />
<android.support.design.widget.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="@dimen/fab_margin"
android:src="@android:drawable/ic_dialog_email" />
</android.support.design.widget.CoordinatorLayout>
logcat 日志猫
Log is, 日志是
04-30 09:13:11.176 10175-10175/com.example.melisa.myformular I/Process: Sending signal.
04-30 10:03:47.128 10427-10427/com.example.melisa.myformular E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.melisa.myformular, PID: 10427 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.melisa.myformular/com.example.melisa.myformular.MainFormular}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com
1 个解决方案
解决方案1
0 已采纳 2016-04-30 10:23:42
Please remove this code and try to run your appliction...... 请删除此代码，然后尝试运行您的应用程序……
In your layout FloatingActionButton view is not there and you are trying to bind and make click event on that ...... 在您的布局中，不存在FloatingActionButton视图，并且您试图在该位置上绑定并使其产生click事件……
FloatingActionButton fab = (FloatingActionButton) findViewById (R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
and this also...... 这也......
@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_formular, menu);
return true;
}
Enjoy coding.... 享受编码...。
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