Question

A simple android Hello World:

MainActivity.java:

package com.amaker.ch02.app;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    private TextView displayTextView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        displayTextView = (TextView)findViewById(R.id.DisplayTextView);
        displayTextView.setText("change in the code");    <--Right if delete the line
    }
}

res/layout/main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:id = "@+id/DisplayTextView"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />

</LinearLayout>

Run, and android will display: sorry, the application has stopped unexpectedly. Please try again., but just as I point in the code MainActivity.java, if I delete the code displayTextView.setText("change in the code");, everything is OK.

What’s wrong with the line of code?

Answer 1

your code seems right. try to clean and build the project. also try to change textview id in xml as well as in your code.your DisplayTextView might coming null so creating this problem. debug the code and find the actual cause. or provide us logcat details.