Android 随机字符串生成器

Question

我有问题。我想绘制一个随机字符串，例如 aXcFg3s2。我在做什么坏事？如何改变我的 random()

private String random;
private String charsEntered;
private EditText et;
private Button ok;
CaptchaInterface.OnCorrectListener mCorrectListener;

public void setOnCorrectListener(CaptchaInterface.OnCorrectListener listener) {
    mCorrectListener = listener;
}

public TextCaptcha(Context context) {
    super(context);
    getWindow().requestFeature(Window.FEATURE_NO_TITLE);
}

public static String random() {
    Random generator = new Random();
    String x = (String) (generator.nextInt(96) + 32);
    return x;
}

public void onCreate(Bundle icicle) {
    setContentView(R.layout.main);
    random = random();
    TextView display = (TextView) findViewById(R.id.textView1);
    display.setText("Random Number: " + random); // Show the random number
    et = (EditText) findViewById(R.id.etNumbers);
    ok = (Button) findViewById(R.id.button1);
    ok.setOnClickListener(this);

}

public void onClick(View arg0) {
    // TODO Auto-generated method stub
    try {
        charsEntered = et.getText().toString();
    } catch (NumberFormatException nfe) {
        Toast.makeText(et.getContext(), "Bla bla bla",
                Toast.LENGTH_LONG).show();
    }

    if (random == charsEntered) {
        Toast.makeText(et.getContext(), "Good!", Toast.LENGTH_LONG).show();
    } else {
        Toast.makeText(et.getContext(), "Bad!", Toast.LENGTH_LONG).show();
    }
}

Answer 1

问题在于您只处理了一个字符而不是使用循环。

您可以创建一个字符数组，其中包含您希望允许出现在随机字符串中的所有字符，然后在循环中从数组中获取一个随机位置并将其添加到 stringBuilder 中。最后，将 stringBuilder 转换为字符串。

---

编辑:这是我建议的简单算法:

private static final String ALLOWED_CHARACTERS ="0123456789qwertyuiopasdfghjklzxcvbnm";

private static String getRandomString(final int sizeOfRandomString)
  {
  final Random random=new Random();
  final StringBuilder sb=new StringBuilder(sizeOfRandomString);
  for(int i=0;i<sizeOfRandomString;++i)
    sb.append(ALLOWED_CHARACTERS.charAt(random.nextInt(ALLOWED_CHARACTERS.length())));
  return sb.toString();
  }

在 Kotlin 上:

companion object {
    private val ALLOWED_CHARACTERS = "0123456789qwertyuiopasdfghjklzxcvbnm"
}

private fun getRandomString(sizeOfRandomString: Int): String {
    val random = Random()
    val sb = StringBuilder(sizeOfRandomString)
    for (i in 0 until sizeOfRandomString)
        sb.append(ALLOWED_CHARACTERS[random.nextInt(ALLOWED_CHARACTERS.length)])
    return sb.toString()
}