Converting ArrayList to an array causes crash

Question

ArrayList<String> myArr = new ArrayList<String>();

then add some stuff to it

myArr.add("Hello");
    myArr.add("Testing");
    myArr.add("Testing 1 2 3 ");

And then I try to convert it to a String array by doing this:

String[] s = (String[])myArr.toArray();

I am going to use this array to eventually populate a listview. . . but it crash when casting and throws this

02-16 22:31:14.835: ERROR/AndroidRuntime(21666): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.IRE.toolbox/org.IRE.toolbox.Mods}: java.lang.ClassCastException: [Ljava.lang.Object;
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2787)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.app.ActivityThread.startActivityNow(ActivityThread.java:2627)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:651)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.widget.TabHost.setCurrentTab(TabHost.java:323)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.widget.TabHost$2.onTabSelectionChanged(TabHost.java:129)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.widget.TabWidget$TabClickListener.onClick(TabWidget.java:453)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.view.View.performClick(View.java:2408)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.view.View$PerformClick.run(View.java:8817)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.os.Handler.handleCallback(Handler.java:587)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.os.Handler.dispatchMessage(Handler.java:92)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.os.Looper.loop(Looper.java:144)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.app.ActivityThread.main(ActivityThread.java:4937)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at java.lang.reflect.Method.invokeNative(Native Method)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at java.lang.reflect.Method.invoke(Method.java:521)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at dalvik.system.NativeStart.main(Native Method)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666): Caused by: java.lang.ClassCastException: [Ljava.lang.Object;
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at org.IRE.toolbox.Mods.onCreate(Mods.java:60)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1069)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2751)
02-16 22:31:14.835: ERROR/AndroidRuntime(21666):     ... 18 more

When I comment out that line it runs fine. Any ideas how I can do this with out it crashing, is it even possible?

Vance Maverick · Accepted Answer · 2011-02-17 04:39:55Z

5

http://download.oracle.com/javase/6/docs/api/java/util/ArrayList.html#toArray%28%29 documents clearly that the return type of toArray() is Object[]. Try

myArray.toArray(new String[0]);

answered Feb 17, 2011 at 4:39

Vance Maverick

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1 Comment

Stephen C Over a year ago

+1 - explains why the OP's application experiences the error.

卢声远 Shengyuan Lu · Accepted Answer · 2011-02-17 04:43:55Z

2

String[] s =  myArr.toArray(new String[myArr.size()]);

answered Feb 17, 2011 at 4:43

卢声远 Shengyuan Lu

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Comments

Vikas Patidar · Accepted Answer · 2011-02-17 04:55:15Z

1

You can also try like this:

    ArrayList<String> myArr = new ArrayList<String>();
    myArr.add("Hello");
    myArr.add("Testing");
    myArr.add("Testing 1 2 3 ");

    Object[] s = myArr.toArray();

    System.out.print(s[0]);
    System.out.print(s[1]);
    System.out.print(s[2]);

answered Feb 17, 2011 at 4:55

Vikas Patidar

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