my first activity runing happen error:Uncaught handler: thread main exiting due to uncaught exceptio

[laker jin]

hrloo.java

   package hello.pak;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class hrllo_act<heloo> extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button btn=(Button)findViewById(R.id.go);
	    btn.setOnClickListener(new View.OnClickListener()
               {

       			public void onClick(View v) {
       		         EditText edt=(EditText)findViewById(R.id.edt);
                 
                        TextView txt= (TextView)findViewById(R.id.txt);
                         txt.setText(getString(R.string.go)+edt.getText());

       			}
                });
    }
} 

main.xml

 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:id="@+id/layout"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView 
	android:id="@+id/txt"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<EditText id="@+id/edt"  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text=""
    />
<Button id="@+id/go"
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="@string/go">
        <requestFocus />
    </Button>
</LinearLayout>   

strings.xml

   <?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="hello">Hello World, hrllo_act!</string>
    <string name="app_name">heloo_app</string>
    <string name="go">go,go,go</string>
</resources>
 

i think maybe folowing code have error:

     EditText edt=(EditText)findViewById(R.id.edt);
                 
                 TextView txt= (TextView)findViewById(R.id.txt); 

thank you!

[Pramod P Deore]

Hi, Laker the problem is in syntax here

  <EditText id="@+id/edt"  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text=""
    />
<Button id="@+id/go"
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="@string/go">
        <requestFocus />
    </Button>  

It should be like this

 <EditText
	android:id="@+id/edt"  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text=""
    />
<Button 
		android:id="@+id/go"
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="@string/go">
        <requestFocus />
    </Button>   

And next time please provide logcat error messages while posting.

[Pramod P Deore]

And welcome to JavaRanch

[laker jin]

Pramod P Deore wrote:And welcome to JavaRanch

so thank you，deore！

the site is so likely! ilike it！

about my problem，it still have erroe, i have change it as you said.

the log is:

  

01-19 05:01:39.397: ERROR/AndroidRuntime(14698): Uncaught handler: thread main exiting due to uncaught exception
01-19 05:01:39.397: ERROR/AndroidRuntime(14698): java.lang.RuntimeException: Unable to start activity ComponentInfo{hello.pak/hello.pak.hrllo_act}: java.lang.NullPointerException
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2401)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2417)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at android.app.ActivityThread.access$2100(ActivityThread.java:116)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at android.os.Looper.loop(Looper.java:123)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at android.app.ActivityThread.main(ActivityThread.java:4203)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at java.lang.reflect.Method.invokeNative(Native Method)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at java.lang.reflect.Method.invoke(Method.java:521)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at dalvik.system.NativeStart.main(Native Method)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698): Caused by: java.lang.NullPointerException
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at hello.pak.hrllo_act.onCreate(hrllo_act.java:17)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2364)
01-19 05:01:39.397: ERROR/AndroidRuntime(14698):     ... 11 more
01-19 05:02:41.497: ERROR/power(985): Failed setting last user activity: g_error=0
  

and i found eclips ,its "Error log" table recommd "argement cant be null"

again thank you !

[Pramod P Deore]

Just after changes in main.xml application run fines on my computer. Try one more time Copy the whole code as you had given in you first post and make changes only in EditText and Button as I told earlier application will definitely run.

[laker jin]

great deore！

after weeken，this programe have normal work！

so thank you，i don‘t know by my poor english to how to discrible my thanks, luck to you!

[Pramod P Deore]

Welcome