Question

So what I’ve done in Eclipse, in layouts I have: activity_main.xml and activity_main2.xml. What I tried is to create a button in activity_main.xml and on click to go on screen of activity_main2.xml

so in com.example.myfirstapp I have

MainActivity.Java:

package com.example.myfirstapp;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.View;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    public void click1(View v) {
        Log.i("clicks","You Clicked B1");
        Intent i=new Intent(
                     MainActivity.this,
                     MainActivity2.class);
        startActivity(i);
    }
}

MainActivity2.java

package com.example.myfirstapp;

import android.os.Bundle;
import android.view.Menu;
import android.app.Activity;

public class MainActivity2 extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
}

Answer 1

Write below code in your MainActivity.java file instead of your code.

public class MainActivity extends Activity implements OnClickListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button mBtn1 = (Button) findViewById(R.id.mBtn1);
        mBtn1.setOnClickListener(this);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    @Override
    public void onClick(View v) {
        Log.i("clicks","You Clicked B1");
        Intent i=new Intent(MainActivity.this, MainActivity2.class);
        startActivity(i);
    }
}

And Declare MainActivity2 into your Androidmanifest.xml file using below code.

<activity
    android:name=".MainActivity2"
    android:label="@string/title_activity_main">
</activity>