public static void main(String[] args) {
String r1 = JOptionPane.showInputDialog("Zadaj retezec");
System.out.println(r1);
String r2 = JOptionPane.showInputDialog("Zadaj retezec ktery chceš vyhledat");
int dlzka = r1.length();
int pocet = 0;

for (int i = 0;i<dlzka;i++) {
String znak = r1.substring(i,i+1);
if ( r2.equals(znak)) pocet++;

}

System.out.println("Zadany retezec se v textu nachazi " + pocet + " krát");


}

}