android studio launch activity from another code example

Example 1: go to activity android

//going to another activity while ending the 
//previous one so that users cannot go back
btListe = (ImageButton)findViewById(R.id.Button_Liste);
    btListe.setOnClickListener(new OnClickListener()
    {    public void onClick(View v)
        {
            intent = new Intent(main.this, ListViewImage.class);
            startActivity(intent);
            finish();
        }
    });

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);