changing activity using intent code example

Example 1: intent android open activity

Intent intent = new Intent(this, DisplayMessageActivity.class);
        intent.putExtra(key:,value:);
        startActivity(intent);

Example 2: navigate to another activity in android

OnClickListener onClickListener = new OnClickListener() {
    @Override
    public void onClick(View v) {
        startActivity(new Intent(action));
    }
};

Button button = (Button) findViewById(id);
button.setOnClickListener(onClickListener);