无法启动活动组件信息java.lang.nullpointerexception需要帮助吗?
嗨,我昨天刚开始学习在android上开发。我的应用程序每次启动前都会停止 我做了一些研究,所以我看了一下我的日志。这是我的日志:无法启动活动组件信息java.lang.nullpointerexception需要帮助吗?,java,android,android-activity,nullpointerexception,Java,Android,Android Activity,Nullpointerexception,嗨,我昨天刚开始学习在android上开发。我的应用程序每次启动前都会停止 我做了一些研究,所以我看了一下我的日志。这是我的日志: FATAL EXCEPTION: main java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myfirstapp/com.example.myfirstapp.MainActivity}: java.lang.NullPointerException at
FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myfirstapp/com.example.myfirstapp.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2295)
E/AndroidRuntime(26645): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349)
E/AndroidRuntime(26645): at android.app.ActivityThread.access$700(ActivityThread.java:159)
E/AndroidRuntime(26645): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316)
E/AndroidRuntime(26645): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(26645): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(26645): at android.app.ActivityThread.main(ActivityThread.java:5419)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1187)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)
我有一节课:
package com.example.myfirstapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.splash);
Thread logo = new Thread (){
public void run(){
try{
int logoTimer = 0;
while (logoTimer <= 5000){
sleep(100);
logoTimer = logoTimer + 100;
}
Intent startActivity = new Intent();
startActivity.setClassName("com.example.myfirstapp", "CLEARSCREEN");
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
finish();
}
}
};
getActionBar().hide();
logo.run();
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
}
@Override
protected void onRestart() {
// TODO Auto-generated method stub
super.onRestart();
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
}
@Override
protected void onStop() {
// TODO Auto-generated method stub
super.onStop();
}
}
package com.example.myfirstapp;
导入android.app.Activity;
导入android.content.Intent;
导入android.os.Bundle;
公共类MainActivity扩展了活动{
@凌驾
创建时受保护的void(Bundle savedInstanceState){
//TODO自动生成的方法存根
super.onCreate(savedInstanceState);
setContentView(R.layout.splash);
螺纹徽标=新螺纹(){
公开募捐{
试一试{
int logoTimer=0;
同时(logoTimer
您应该创建两个活动。第一个是启动屏幕活动,第二个是主活动。我在清单文件中只看到一个。使用intent to SecondActivity.class
更好地使用同步的安全方法编写代码,例如:
私有线程mSplashThread
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.splashscreen);
final SplashScreen sPlashScreen = this;
mSplashThread = new Thread(){
@Override
public void run(){
try {
synchronized(this){
wait(3000);
}
}
catch(InterruptedException ex){
}
finish();
Intent intent = new Intent();
intent.setClass(sPlashScreen, MainActivity.class);
startActivity(intent);
}
};
mSplashThread.start();
}
尝试在线程构造函数中放置一个Runnable
。
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.splashscreen);
final SplashScreen sPlashScreen = this;
mSplashThread = new Thread(){
@Override
public void run(){
try {
synchronized(this){
wait(3000);
}
}
catch(InterruptedException ex){
}
finish();
Intent intent = new Intent();
intent.setClass(sPlashScreen, MainActivity.class);
startActivity(intent);
}
};
mSplashThread.start();
}