---

try {
    Process process = Runtime.getRuntime().exec("su");
    java.io.DataOutputStream os = new java.io.DataOutputStream(process.getOutputStream());
    os.writeBytes("id\n");
    os.writeBytes("exit\n");
    os.flush();
    process.waitFor();
    boolean hasRoot = process.exitValue() == 0;
    textview1.setText(hasRoot ? "ROOT OK" : "NO ROOT");
} catch (Exception e) {
    textview1.setText("ERROR");
}