Question

Suddenly my buttons cause null pointer exceptions. I have not changed any code in this activity class. I have been up most of the weekend trying to pin this down. I get null pointer exceptions in both the emulator and on device.

This is a simple screen with buttons. I could easily scrap this and write new code, but would like to know what has caused this issue. If not, I will just write new code.

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;


Button b1 = (Button) findViewById(R.id.MainActBtn);

b1.setOnClickListener(new View.OnClickListener() { //Error is here

        public void onClick(View v) {
            Intent intent = new Intent(StartScreen.this, MainActivity.class);
            startActivity(intent);

        }
    });

Any help?

Answer 1

Try a fresh clean and build of your project. I got this error too in the past, caused by a changed R.class Resource class, but the static references in the using classes weren’t properly replaced by the incremental java compiler, so the resources are no longer found.