java无法实例化安卓编程类
我在这里观看了教程视频：http://www.youtube.com/watch?v=pZaRNVwKAy4&list=PLB03EA9545DD188C3&index=7，在观看教程时遇到了一些错误。在我开始学习教程：onCheckedChanged方法之前，一切都很顺利。有人能解释一下我做错了什么吗？非常感谢
LogCat代码
09-15 18:38:22.444: E/MediaPlayer(1764): Should have subtitle controller already set
09-15 18:38:27.984: E/MediaPlayer(1764): Should have subtitle controller already set
09-15 18:38:31.374: E/AndroidRuntime(1764): FATAL EXCEPTION: main
09-15 18:38:31.374: E/AndroidRuntime(1764): Process: com.example.myfirstapp, PID: 1764
09-15 18:38:31.374: E/AndroidRuntime(1764): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.myfirstapp/com.example.myfirstapp.TutorialOne}: java.lang.InstantiationException: can't instantiate class com.example.myfirstapp.TutorialOne
09-15 18:38:31.374: E/AndroidRuntime(1764): at 安卓.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121)
09-15 18:38:31.374: E/AndroidRuntime(1764): at 安卓.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
09-15 18:38:31.374: E/AndroidRuntime(1764): at 安卓.app.ActivityThread.access$800(ActivityThread.java:135)
09-15 18:38:31.374: E/AndroidRuntime(1764): at 安卓.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
09-15 18:38:31.374: E/AndroidRuntime(1764): at 安卓.os.Handler.dispatchMessage(Handler.java:102)
09-15 18:38:31.374: E/AndroidRuntime(1764): at 安卓.os.Looper.loop(Looper.java:136)
09-15 18:38:31.374: E/AndroidRuntime(1764): at 安卓.app.ActivityThread.main(ActivityThread.java:5017)
09-15 18:38:31.374: E/AndroidRuntime(1764): at java.lang.reflect.Method.invokeNative(Native Method)
09-15 18:38:31.374: E/AndroidRuntime(1764): at java.lang.reflect.Method.invoke(Method.java:515)
09-15 18:38:31.374: E/AndroidRuntime(1764): at com.安卓.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
09-15 18:38:31.374: E/AndroidRuntime(1764): at com.安卓.internal.os.ZygoteInit.main(ZygoteInit.java:595)
09-15 18:38:31.374: E/AndroidRuntime(1764): at dalvik.system.NativeStart.main(Native Method)
09-15 18:38:31.374: E/AndroidRuntime(1764): Caused by: java.lang.InstantiationException: can't instantiate class com.example.myfirstapp.TutorialOne
09-15 18:38:31.374: E/AndroidRuntime(1764): at java.lang.Class.newInstanceImpl(Native Method)
09-15 18:38:31.374: E/AndroidRuntime(1764): at java.lang.Class.newInstance(Class.java:1208)
09-15 18:38:31.374: E/AndroidRuntime(1764): at 安卓.app.Instrumentation.newActivity(Instrumentation.java:1061)
09-15 18:38:31.374: E/AndroidRuntime(1764): at 安卓.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112)
09-15 18:38:31.374: E/AndroidRuntime(1764): ... 11 more
主Java代码
package com.example.myfirstapp;
import 安卓.app.Activity;
import 安卓.content.Intent;
import 安卓.media.MediaPlayer;
import 安卓.os.Bundle;
public class Main extends Activity {
// declare variables for the who class
MediaPlayer logoMusic;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.splash);
// start music command
logoMusic=MediaPlayer.create(Main.this, R.raw.melody);
logoMusic.start();
// start thread
Thread logoTimer=new Thread(){
public void run(){
try {
sleep(5000); // 1k is 1sec
Intent menuIntent=new Intent("com.example.myfirstapp.MENU");// address in manifest
startActivity(menuIntent);
} catch (InterruptedException e) {
e.printStackTrace();
}
finally
{
finish();
}
}
};
logoTimer.start();
}
@Override
protected void onPause() {
super.onPause();
logoMusic.release();
}
}
菜单Java代码
package com.example.myfirstapp;
import 安卓.app.Activity;
import 安卓.content.Intent;
import 安卓.media.MediaPlayer;
import 安卓.os.Bundle;
import 安卓.view.View;
import 安卓.widget.Button;
public class Menu extends Activity{
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final MediaPlayer buttonSound=MediaPlayer.create(Menu.this, R.raw.button);// make sure it is a final variable bc u are using it in sub
// set up buttons reference
Button tut1=(Button) findViewById(R.id.tutorial1);
Button tut2=(Button) findViewById(R.id.tutorial2);
// setting up the button functions
tut1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
buttonSound.start();
startActivity(new Intent("com.example.myfirstapp.TutorialOne"));// short cut in creating the intent
}
});
tut2.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
buttonSound.start();
startActivity(new Intent("com.example.myfirstapp.TutorialOne"));
}
});
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
}
}
java代码教程
package com.example.myfirstapp;
import 安卓.annotation.SuppressLint;
import 安卓.app.Activity;
import 安卓.os.Bundle;
import 安卓.view.Gravity;
import 安卓.view.View;
import 安卓.widget.Button;
import 安卓.widget.CompoundButton;
import 安卓.widget.CompoundButton.OnCheckedChangeListener;
import 安卓.widget.EditText;
import 安卓.widget.RadioGroup;
import 安卓.widget.TextView;
@SuppressLint("RtlHardcoded")
public abstract class TutorialOne extends Activity implements OnCheckedChangeListener{
// set up variables
TextView textOut;
EditText textIn;
RadioGroup gravityG,styleG;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.tutorial1);
//similar to how you set the button to reference to xml
textOut=(TextView)findViewById(R.id.tvChange);
textIn=(EditText)findViewById(R.id.editText1);
gravityG=(RadioGroup)findViewById(R.id.rgGravity);
styleG=(RadioGroup)findViewById(R.id.rgStyle);
Button gen=(Button)findViewById(R.id.generate);
gen.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
// when you click generate, it will text out
textOut.setText(textIn.getText());// get user input and output
}
});
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
}
public void onCheckedChanged(CompoundButton buttonView, int isChecked) {
// TODO Auto-generated method stub
switch(isChecked){
case R.id.rbLeft:
textOut.setGravity(Gravity.LEFT);// set gravity to left
break;
case R.id.rbCenter:
textOut.setGravity(Gravity.CENTER);
break;
case R.id.rbRight:
textOut.setGravity(Gravity.RIGHT);
break;
}
}}
梅因。xml
<RelativeLayout xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
xmlns:tools="http://schemas.安卓.com/tools"
安卓:layout_width="match_parent"
安卓:layout_height="match_parent"
安卓:paddingBottom="@dimen/activity_vertical_margin"
安卓:paddingLeft="@dimen/activity_horizontal_margin"
安卓:paddingRight="@dimen/activity_horizontal_margin"
安卓:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.myfirstapp.Main" >
<Button
安卓:id="@+id/tutorial1"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:text="@string/button1" />
<Button
安卓:id="@+id/tutorial2"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:layout_marginTop="31dp"
安卓:text="@string/button2" />
</RelativeLayout>
飞溅。xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
安卓:layout_width="match_parent"
安卓:layout_height="match_parent"
安卓:orientation="vertical"
安卓:background="@drawable/flash">
</LinearLayout>
教程1。xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
安卓:layout_width="match_parent"
安卓:layout_height="match_parent"
安卓:orientation="vertical" >
<EditText
安卓:id="@+id/editText1"
安卓:layout_width="match_parent"
安卓:layout_height="wrap_content"
安卓:ems="10"
安卓:text=""
安卓:textStyle="bold" >
<requestFocus />
</EditText>
<LinearLayout
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:orientation="horizontal"
安卓:weightSum="2" >
<TextView
安卓:id="@+id/tvStyle"
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:layout_weight="1"
安卓:text="@string/style"
安卓:gravity="center" />
<TextView
安卓:id="@+id/tvGravity"
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:layout_weight="1"
安卓:gravity="center"
安卓:text="@string/gravity" />
</LinearLayout>
<LinearLayout
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:orientation="horizontal"
安卓:weightSum="2" >
<RadioGroup
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:layout_weight="1"
安卓:orientation="vertical"
安卓:id="@+id/rgStyle" >
<RadioButton
安卓:id="@+id/rbNormal"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:text="@string/normal" />
<RadioButton
安卓:id="@+id/rbItalic"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:text="@string/italic" />
<RadioButton
安卓:id="@+id/rbBold"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:text="@string/bold" />
</RadioGroup>
<RadioGroup
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:layout_weight="1"
安卓:orientation="vertical"
安卓:id="@+id/rgGravity" >
<RadioButton
安卓:id="@+id/rbLeft"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:text="@string/left" />
<RadioButton
安卓:id="@+id/rbCenter"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:text="@string/center" />
<RadioButton
安卓:id="@+id/rbRight"
安卓:layout_width="wrap_content"
安卓:layout_height="wrap_content"
安卓:text="@string/right" />
</RadioGroup>
</LinearLayout>
<TextView
安卓:id="@+id/tvChange"
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:gravity="center"
安卓:text="@string/text_view_change"
安卓:textStyle="bold" />
<Button
安卓:id="@+id/generate"
安卓:layout_width="fill_parent"
安卓:layout_height="wrap_content"
安卓:text="@string/generate"
安卓:textSize="25sp" />
</LinearLayout>
AndroidManifest代码
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
package="com.example.myfirstapp"
安卓:versionCode="1"
安卓:versionName="1.0" >
<uses-sdk
安卓:minSdkVersion="8"
安卓:targetSdkVersion="21" />
<application
安卓:allowBackup="true"
安卓:icon="@drawable/ic_launcher"
安卓:label="@string/app_name"
安卓:theme="@style/AppTheme" >
<activity
安卓:name=".Main"
安卓:label="@string/app_name" >
<intent-filter>
<action 安卓:name="安卓.intent.action.MAIN" />
<category 安卓:name="安卓.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
安卓:name=".Menu"
安卓:label="@string/app_name" >
<intent-filter>
<action 安卓:name="com.example.myfirstapp.MENU" />
<category 安卓:name="安卓.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity
安卓:name=".TutorialOne"
安卓:label="@string/app_name" >
<intent-filter>
<action 安卓:name= "com.example.myfirstapp.TutorialOne" />
<category 安卓:name="安卓.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
</manifest>
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