setText causes nullPointerException, very simple, but no idea (android)

Question

I am new in android development and have spent couple of hours on this. (eclipse + adt) Here are some extra words so i can post this. Getting Null pointer exception while calling run_time.setText("t");

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_start_run);    
        TextView run_time = (TextView) findViewById(R.id.run_time);

        try {
            run_time.setText("t");
        }catch(Exception e) {
            Log.i("Log", e.getMessage()+"Error!"); // LogCat message
        }

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }

    }

layout activity_start_run.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >

    <TextView 
    android:id="@+id/run_time"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="ghjghjghjghjghjghj" />

</LinearLayout>

Answer 1

This Null Pointer Exception is because your resource is not loaded properly try to clean project and run again will resolve.

R.id.run_time this is loaded from R.java which is auto generated file. Clean and rebuilt project will fix this.

MainActivity.java

package com.example.stacktest;

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

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        TextView run_time = (TextView) findViewById(R.id.run_time);
        try {
            run_time.setText("t");
        }catch(Exception e) {
            Log.i("Log", e.getMessage()+"Error!"); // LogCat message
        }
    }
}

and activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >

    <TextView
        android:id="@+id/run_time"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ghjghjghjghjghjghj" />

</LinearLayout>