What's wrong in this simple android Program, I get 'Force Close'

What is wrong in this program, My eclipse IDE doesn't show any errors....when I execute this simple program the emulator shows force close....Anybody please clarify

import android.app.Activity;
import android.view.View.OnClickListener;
import android.view.View;
import android.os.Bundle;
import android.widget.*;

public class HelloWorld extends A开发者_如何学运维ctivity implements OnClickListener {
    /** Called when the activity is first created. */
    View Et1,Bt1,TxtDisp;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.name_getter);
        Bt1=(Button)findViewById(R.id.Btn1);
        Et1=(EditText)findViewById(R.id.UserInput);
        TxtDisp=(TextView)findViewById(R.id.TextDisp);
        Bt1.setOnClickListener(this);      
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        String userInput=((EditText) Et1).getText().toString();
        ((TextView)TxtDisp).setText(userInput);
    }
}

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Do you know how to enable logcat?

please enable logcat and show us the exact exception it is throwing.

in eclipse, it is: Window>Show View>Other>Android>Logcat

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Can you post your main.xml here. Something must have gone wrong there. Check whether you have assigned correct names for each view under android:id in your layout

My guess is there should be a null pointer thrown at this line

Bt1.setOnClickListener(this); 

Can you check whether Bt1 is null? if yes your object has not been initialized properly.

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Without an error this is really hard,

• Have you declared your activity in the manifest?
• Does that contentview "name_getter" contain the ids Btn1, UserInput and TextDisp?
• Are those id's indeed respectively a Button, an EditText and a Textview?

Does the error start after clicking the button? Could it be that your getText returns null?

If you really can't get the logcat to work, at least add a bunch of try-catches to your code. If it executes you're getting an error in this file, and not somewhere else. You coudl also try to debug with debugmessages using a Toast.

(something like this, just guessing, you should look it up)

Toast t = Toast.maketext(this, "your error", Toast.LOOKTHISUP);
t.show();

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Something similar happened to me once.

Are you sure that

R.id.Btn1 is Button
R.id.UserInput is EditText
R.id.TextDisp is TextView

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try to do this:

public void onClick(View V) { switch(v.getId(){ case R.id.Bt1: // do here what you want to do break; } }