Java 无法使用可运行的
我使用Java 无法使用可运行的,java,android,Java,Android,我使用Runnable作为计时器,交替运行一个块 我从中获得此代码,并将其更改为: public class TikingTimer { private long countDownInterval; private boolean status; public TikingTimer(long pCountDownInterval) { this.countDownInterval = pCountDownInterval; statu
Runnable
作为计时器
,交替运行一个块
我从中获得此代码,并将其更改为:
public class TikingTimer {
private long countDownInterval;
private boolean status;
public TikingTimer(long pCountDownInterval) {
this.countDownInterval = pCountDownInterval;
status = false;
Initialize();
}
public void Stop() {
status = false;
}
public void Start() {
status = true;
}
public void Initialize()
{
final Handler handler = new Handler();
final Runnable counter = new Runnable(){
public void run(){
if(status) {
//TODO my code
} else {
handler.postDelayed(this, countDownInterval);
}
}
};
handler.postDelayed(counter, countDownInterval);
}
}
。。。在我使用的onCreate
方法中:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TikingTimer tt = new TikingTimer(1000);
tt.Start();
}
但是当我运行这个项目时,它就关闭了
在onCreate
方法中使用Runnable
是否错误
谢谢
LogCat堆栈跟踪是:
08-11 13:04:55.384: E/AndroidRuntime(3125): FATAL EXCEPTION: main
08-11 13:04:55.384: E/AndroidRuntime(3125): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{kawthar.taghvimdigital/kawthar.taghvimdigital.MainActivity}: java.lang.NullPointerException
08-11 13:04:55.384: E/AndroidRuntime(3125): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2106)
08-11 13:04:55.384: E/AndroidRuntime(3125): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
08-11 13:04:55.384: E/AndroidRuntime(3125): at android.app.ActivityThread.access$600(ActivityThread.java:141)
08-11 13:04:55.384: E/AndroidRuntime(3125): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
08-11 13:04:55.384: E/AndroidRuntime(3125): at android.os.Handler.dispatchMessage(Handler.java:99)
08-11 13:04:55.384: E/AndroidRuntime(3125): at android.os.Looper.loop(Looper.java:137)
08-11 13:04:55.384: E/AndroidRuntime(3125): at android.app.ActivityThread.main(ActivityThread.java:5041)
08-11 13:04:55.384: E/AndroidRuntime(3125): at java.lang.reflect.Method.invokeNative(Native Method)
08-11 13:04:55.384: E/AndroidRuntime(3125): at java.lang.reflect.Method.invoke(Method.java:511)
08-11 13:04:55.384: E/AndroidRuntime(3125): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
08-11 13:04:55.384: E/AndroidRuntime(3125): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
08-11 13:04:55.384: E/AndroidRuntime(3125): at dalvik.system.NativeStart.main(Native Method)
08-11 13:04:55.384: E/AndroidRuntime(3125): Caused by: java.lang.NullPointerException
08-11 13:04:55.384: E/AndroidRuntime(3125): at android.app.Activity.findViewById(Activity.java:1839)
08-11 13:04:55.384: E/AndroidRuntime(3125): at kawthar.taghvimdigital.MainActivity.<init>(MainActivity.java:14)
08-11 13:04:55.384: E/AndroidRuntime(3125): at java.lang.Class.newInstanceImpl(Native Method)
08-11 13:04:55.384: E/AndroidRuntime(3125): at java.lang.Class.newInstance(Class.java:1319)
08-11 13:04:55.384: E/AndroidRuntime(3125): at android.app.Instrumentation.newActivity(Instrumentation.java:1054)
08-11 13:04:55.384: E/AndroidRuntime(3125): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
08-11 13:04:55.384: E/AndroidRuntime(3125): ... 11 more
08-11 13:04:55.384:E/AndroidRuntime(3125):致命异常:main
08-11 13:04:55.384:E/AndroidRuntime(3125):java.lang.RuntimeException:无法实例化活动组件信息{kawthar.taghvimdigital/kawthar.taghvimdigital.MainActivity}:java.lang.NullPointerException
08-11 13:04:55.384:E/AndroidRuntime(3125):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2106)
08-11 13:04:55.384:E/AndroidRuntime(3125):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
08-11 13:04:55.384:E/AndroidRuntime(3125):在android.app.ActivityThread.access$600(ActivityThread.java:141)
08-11 13:04:55.384:E/AndroidRuntime(3125):在android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
08-11 13:04:55.384:E/AndroidRuntime(3125):在android.os.Handler.dispatchMessage(Handler.java:99)上
08-11 13:04:55.384:E/AndroidRuntime(3125):在android.os.Looper.loop(Looper.java:137)
08-11 13:04:55.384:E/AndroidRuntime(3125):位于android.app.ActivityThread.main(ActivityThread.java:5041)
08-11 13:04:55.384:E/AndroidRuntime(3125):位于java.lang.reflect.Method.Invokenactive(本机方法)
08-11 13:04:55.384:E/AndroidRuntime(3125):位于java.lang.reflect.Method.invoke(Method.java:511)
08-11 13:04:55.384:E/AndroidRuntime(3125):在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
08-11 13:04:55.384:E/AndroidRuntime(3125):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
08-11 13:04:55.384:E/AndroidRuntime(3125):在dalvik.system.NativeStart.main(本机方法)
08-11 13:04:55.384:E/AndroidRuntime(3125):由以下原因引起:java.lang.NullPointerException
08-11 13:04:55.384:E/AndroidRuntime(3125):在android.app.Activity.findViewById(Activity.java:1839)
08-11 13:04:55.384:E/AndroidRuntime(3125):在kawthar.taghvimdigital.MainActivity。(MainActivity.java:14)
08-11 13:04:55.384:E/AndroidRuntime(3125):位于java.lang.Class.newInstanceImpl(本机方法)
08-11 13:04:55.384:E/AndroidRuntime(3125):位于java.lang.Class.newInstance(Class.java:1319)
08-11 13:04:55.384:E/AndroidRuntime(3125):在android.app.Instrumentation.newActivity(Instrumentation.java:1054)上
08-11 13:04:55.384:E/AndroidRuntime(3125):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2097)
2008-11 13:04:55.384:E/AndroidRuntime(3125):。。。还有11个
在MainActivity(未发布)的第14行,您通过以下方法查找视图:
findViewById(Activity.java:1839)
。。。这是找不到的
由于您以某种方式操纵此视图,因此会抛出您发布的NullPointerException
。您试图访问的视图未在主活动的xml布局中定义
检查主活动上的第14行
此问题不是由于Runnable造成的。请编辑并添加日志猫中的完整stacktrace。是否覆盖活动的构造函数?stacktrace看起来像是从活动的构造函数调用findViewById()。能否发布完整的OnCreate代码供我们查看。因为问题不在可运行范围内。