You can try the following code :
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main); //If your layout is main.xml
TextView tv = (TextView)findViewById(R.id.TextView01);
tv.setText("Hello, Android\n");
}
The Root Cause of the error is R.id.TextView01 is NULL, if you do not call
setContentView(R.layout.main);
2009/5/15 Francesco Pace <paxa...@gmail.com>
> Thanks, but I have same error.
> New code is :
>
> public void onCreate(Bundle savedInstanceState) {
> super.onCreate(savedInstanceState);
> TextView tv = (TextView)this.findViewById(R.id.TextView01);
> setContentView(tv);
> tv.setText("Hello, Android\n");
> }
>
> Boh.....
>
> 2009/5/15 Robert <robert.li.ruim...@gmail.com>
>
>> You can try it to move setcontextview() to the first line in oncreate
>> function.good lock.
>>
>> Francesco Pace <paxa...@gmail.com>写道：
>>
>>
>> >Thanks, but I have this error :
>> >
>> >ERROR/AndroidRuntime(1096): java.lang.RuntimeException: Unable to start
>> >activity
>>
>> >ComponentInfo{com.cecco.android.hello/com.cecco.android.hello.HelloWorld}:
>> >java.lang.NullPointerException: println needs a message
>> >
>> >in my code :
>> >
>> >public void onCreate(Bundle savedInstanceState) {
>> > super.onCreate(savedInstanceState);
>> >
>> > TextView tv = (TextView)this.findViewById(R.id.TextView01);
>> > tv.setText("Hello, Android\n");
>> > setContentView(tv);
>> > }
>> >
>> >But when I use this statement "TextView tv = new TextView(this) my
>> >application running correctly.
>> >My main.xml file is :
>> >
>> ><LinearLayout
>> > android:id="@+id/LinearLayout01"
>> > android:layout_width="fill_parent"
>> > android:layout_height="fill_parent"
>> > xmlns:android="
>> http://schemas.android.com/apk/res/android
>> >">
>> > <TextView
>> > android:text="TextView01"
>> > android:id="@+id/TextView01"
>> > android:layout_width="wrap_content"
>> > android:layout_height="wrap_content">
>> > </TextView>
>> ></LinearLayout>
>> >
>> >and my R.java :
>> >
>> >public final class R {
>> > public static final class attr {
>> > }
>> > public static final class drawable {
>> > public static final int icon=0x7f020000;
>> > }
>> > public static final class id {
>> > public static final int LinearLayout01=0x7f050000;
>> > public static final int TextView01=0x7f050001;
>> > }
>> > public static final class layout {
>> > public static final int main=0x7f030000;
>> > }
>> > public static final class string {
>> > public static final int app_name=0x7f040001;
>> > public static final int hello=0x7f040000;
>> > }
>> >
>> >2009/5/15 iDeveloper <ideveloper...@gmail.com>
>> >
>> >> If you just want to print these on the activity, use a TextView and set
>> its
>> >> text to your sysouts
>> >> TextView tv = (TextView)findViewById...
>> >> tv.setText("Whatever you want to print");
>> >>
>> >>
>> >>
>> >>
>> >> On 15-May-09, at 1:54 PM, Francesco Pace wrote:
>> >>
>> >> Hi, thanks.
>> >> But I want print these informations on my android application......
>> There
>> >> is a particular UI?
>> >>
>> >> 2009/5/15 iDeveloper <ideveloper...@gmail.com>
>> >>
>> >>> You can use Log.d for printing debug statements to the LogCat and
>> Log.e
>> >>> for error statements.
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> On 15-May-09, at 1:25 PM, Francesco Pace wrote:
>> >>>
>> >>> Hi Mariano, thanks for your time.
>> >>> Example :
>> >>>
>> >>> ///// CODE APPLICATION
>> >>> *System.out.println("Hello");
>> >>> foo1(); // Simple function
>> >>> System.out.println("World");
>> >>> foo2(); // Simple function
>> >>> System.out.println("Today");
>> >>> System.out.println("Yesterday");*
>> >>>
>> >>> I know that I can't use "System.out.println" on Android.
>> >>>
>> >>> ///// DISPLAY CONSOLE (NO WINDOW COMMAND LINE)
>> >>> *- Hello
>> >>> - World (after foo1())
>> >>> - Today (after foo2())
>> >>> - Yesterday*
>> >>>
>> >>> "adb -e logcat" display the output of the currently running emulator
>> on
>> >>> window command line, I need to show "logs" on interface.
>> >>> Can you help me? Thanks for all.
>> >>>
>> >>> 2009/5/15 Mariano Kamp <mariano.k...@gmail.com>
>> >>>
>> >>>> Not sure if I understand you correctly.
>> >>>> You can run "adb -e logcat" on the command line to display the output
>> of
>> >>>> the currently running emulator. Is that what are looking for?
>> >>>>
>> >>>>
>> >>>> On Fri, May 15, 2009 at 9:32 AM, Francesco Pace <paxa...@gmail.com
>> >wrote:
>> >>>>
>> >>>>> Hi developers,
>> >>>>> I need a help. I need to display all Logcats Log on console of my
>> >>>>> emulator, as do it the simple program "Hello World".
>> >>>>> Can you help me?
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>
>> >>>>
>> >>>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> >
>> >>
>> >
>> >>
>>
>>
>>
>
> >
>
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