我是 android studio 的新手。在 android studio 上运行设备时出现 Nullpointer 异常。我正在为 arm 处理器使用 armeabi-v7a sdk。错误看起来像这样..
null
java.lang.NullPointerException
at com.android.tools.idea.run.AndroidSessionInfo.isEmbeddable(AndroidSessionInfo.java:62)
at com.android.tools.idea.run.AndroidRunConfigurationBase.getOldSessionTarget(AndroidRunConfigurationBase.java:307)
at com.android.tools.idea.run.AndroidRunConfigurationBase.getState(AndroidRunConfigurationBase.java:279)
at com.intellij.execution.runners.ExecutionEnvironment.getState(ExecutionEnvironment.java:201)
at com.intellij.execution.runners.BaseProgramRunner.execute(BaseProgramRunner.java:58)
at com.intellij.execution.runners.GenericProgramRunner.execute(GenericProgramRunner.java:31)
at com.intellij.execution.runners.BaseProgramRunner.execute(BaseProgramRunner.java:53)
at com.intellij.execution.runners.GenericProgramRunner.execute(GenericProgramRunner.java:31)
at com.intellij.execution.ProgramRunnerUtil.executeConfiguration(ProgramRunnerUtil.java:94)
at com.intellij.execution.impl.ExecutionManagerImpl.start(ExecutionManagerImpl.java:396)
at com.intellij.execution.impl.ExecutionManagerImpl.access$400(ExecutionManagerImpl.java:61)
at com.intellij.execution.impl.ExecutionManagerImpl$5.run(ExecutionManagerImpl.java:384)
at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)
at com.intellij.util.Alarm$Request$1.run(Alarm.java:351)
at com.intellij.openapi.application.impl.LaterInvocator$FlushQueue.run(LaterInvocator.java:332)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:734)
at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:569)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:382)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
list :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.de34.myfirstapp">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity
android:name=".MainActivity"
android:label="@string/app_name"
android:theme="@style/AppTheme.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
我的 gradle 看起来像:
apply plugin: 'com.android.application'
android {
compileSdkVersion 23
buildToolsVersion "23.0.1"
defaultConfig {
applicationId "com.example.de34.myfirstapp"
minSdkVersion 15
targetSdkVersion 21
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(include: ['*.jar'], dir: 'libs')
//testCompile 'junit:junit:4.12'
compile 'com.android.support:appcompat-v7:23.1.1'
compile 'com.android.support:design:23.1.1'
}
主要 Activity 节点:
package com.example.de34.myfirstapp;
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;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
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, menu);
return true;
}
public void OnclickMe(View view){
Toast toast=Toast.makeText(this,"oh you clicked",Toast.LENGTH_LONG);
toast.show();
}
@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);
}
}
XML:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
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"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="com.example.de34.myfirstapp.MainActivity"
tools:showIn="@layout/activity_main">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!click me if you dare"
android:id="@+id/textView"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/clickMe"
android:id="@+id/button"
android:layout_marginTop="44dp"
android:layout_below="@+id/textView"
android:layout_centerHorizontal="true" />
</RelativeLayout>
最佳答案
你必须在布局文件中添加工具栏，如下所示
<include layout="@layout/app_bar"
android:id="@+id/toolbar"/>
假设这是您的app_bar.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:contentInsetEnd="0dp"
app:contentInsetStart="0dp"
android:background="@color/blue"
android:minHeight="?attr/actionBarSize">
<TextView
android:id="@+id/toolbar_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="My App Bar"
android:textColor="@android:color/white"
android:textSize="32sp"
/>
</android.support.v7.widget.Toolbar>
关于android - 尝试在 android studio 上运行设备时出现 NullPointer 异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35285344/