解决：Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x2

　　在运行Android app时出现以下错误：

   --------- beginning of crash
11-28 07:53:56.485 6712-6712/com.trojane.android.learnactivity E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.trojane.android.learnactivity, PID: 6712
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.trojane.android.learnactivity/com.trojane.android.learnactivity.SecondActivity}: android.content.res.Resources$NotFoundException: String resource ID #0x2
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x2
        at android.content.res.Resources.getText(Resources.java:348)
        at android.widget.Toast.makeText(Toast.java:307)
        at com.trojane.android.learnactivity.SecondActivity.onCreate(SecondActivity.java:19)
        at android.app.Activity.performCreate(Activity.java:7136)
        at android.app.Activity.performCreate(Activity.java:7127)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 

而出错的代码是：

Toast.makeText(SecondActivity.this,getIntent().getIntExtra("initNum",1),Toast.LENGTH_LONG)

原因： makeText 中的 int 类型的被认为是 Resource ID

解决方法：将 int 类型数值改成 String