在運行Android app時出現以下錯誤:
--------- 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)
而出錯的代碼是:
Toast.makeText(SecondActivity.this,getIntent().getIntExtra("initNum",1),Toast.LENGTH_LONG).show()
那么我們就看一下 makeText 方法的源代碼:
public static Toast makeText(Context context, CharSequence text, @Duration int duration) { return makeText(context, null, text, duration); }
可以看到該方法中第二個參數的類型是 CharSequence 類型的, 那么CharSequence 是什么類型呢?我們可以看下圖:
從上面這個圖可以看出 CharSequence 是個接口類型,他的子類有我們熟悉的char、String、StringBuffer 等類型,應該說所有的字符類型都是直接或者間接實現了這個接口,
所以,對於makeText的第二個參數只能傳入一個字符型。
原因: makeText 中第二個參數只能是CharSequence的直接或間接實現類,而傳入的 int 類型的被認為是String Resource ID
解決方法:將 int 類型數值改成 String或其他字符型