无法启动 activity Android 模拟器
Unable to start activity Android Emulator
我是 Android 编程新手。我正在按照 Android 开发人员的指南开始使用 Android。
在模拟器上尝试 运行 简单公式时，模拟器显示
"Unfortunately, My First App has stopped.",
其中 MyFormular 是应用程序的名称。问题是我从布局资源文件制作了新布局，并试图连接到新的 loyout fror here
setContentView(R.layout.form_layout (the new layout is form_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
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);
}
}
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
日志是，
04-30 09:13:11.176 10175-10175/com.example.melisa.myformular I/Process: Sending signal. PID: 10175 SIG: 9
04-30 10:03:45.336 10427-10427/com.example.melisa.myformular W/System: ClassLoader referenced unknown path: /data/app/com.example.melisa.myformular-1/lib/x86
04-30 10:03:47.008 10427-10427/com.example.melisa.myformular W/System: ClassLoader referenced unknown path: /data/app/com.example.melisa.myformular-1/lib/x86
04-30 10:03:47.112 10427-10427/com.example.melisa.myformular W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
04-30 10:03:47.128 10427-10427/com.example.melisa.myformular D/AndroidRuntime: Shutting down VM
04-30 10:03:47.128 10427-10427/com.example.melisa.myformular E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.melisa.myformular, PID: 10427
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.melisa.myformular/com.example.melisa.myformular.MainFormular}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View$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$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.example.melisa.myformular.MainFormular.onCreate(MainFormular.java:22)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$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.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
请删除此代码并尝试运行您的应用......
在您的布局中没有 FloatingActionButton 视图，您正在尝试绑定并在其上创建点击事件......
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();
}
});
还有这个……
@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;
}
享受编码....
我是 Android 编程新手。我正在按照 Android 开发人员的指南开始使用 Android。 在模拟器上尝试 运行 简单公式时，模拟器显示
"Unfortunately, My First App has stopped.",
其中 MyFormular 是应用程序的名称。问题是我从布局资源文件制作了新布局，并试图连接到新的 loyout fror here
setContentView(R.layout.form_layout (the new layout is form_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
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);
}
}
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
日志是，
04-30 09:13:11.176 10175-10175/com.example.melisa.myformular I/Process: Sending signal. PID: 10175 SIG: 9 04-30 10:03:45.336 10427-10427/com.example.melisa.myformular W/System: ClassLoader referenced unknown path: /data/app/com.example.melisa.myformular-1/lib/x86 04-30 10:03:47.008 10427-10427/com.example.melisa.myformular W/System: ClassLoader referenced unknown path: /data/app/com.example.melisa.myformular-1/lib/x86 04-30 10:03:47.112 10427-10427/com.example.melisa.myformular W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable 04-30 10:03:47.128 10427-10427/com.example.melisa.myformular D/AndroidRuntime: Shutting down VM
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.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.melisa.myformular.MainFormular.onCreate(MainFormular.java:22) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
请删除此代码并尝试运行您的应用......
在您的布局中没有 FloatingActionButton 视图，您正在尝试绑定并在其上创建点击事件......
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();
}
});
还有这个……
@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;
}
享受编码....