android - 如何在android中使用TransformationMethod

Question

我想创建一个接受密码的EditText。我想在输入后立即隐藏该字符。因此，我使用了 TransformationMethod。我是新手，所以尝试了以下代码。

EditText editText = (EditText) findViewById(R.id.editText);
editText.setTransformationMethod(new PasswordTransformationMethod());


private class PasswordTransformationMethod extends Transformation implements TransformationMethod {

    @Override
    public CharSequence getTransformation(CharSequence source, View view) {
        return "/";
    }

    @Override
    public void onFocusChanged(View view, CharSequence source, boolean focused, int direction, Rect previouslyFocusedRect) {
        source = getTransformation(source, view);
    }
}

但是，它抛出，

01-03 10:22:35.750: E/AndroidRuntime(2102): java.lang.IndexOutOfBoundsException

我错过了一些东西。任何帮助将不胜感激。

Answer 1

上面的方法有很多错误。

因此，我正在分享我用来将密码转换为点的代码。

像这样在同一个 Java 文件中创建一个单独的类，

public class MyPasswordTransformationMethod extends PasswordTransformationMethod {

    @Override
    public CharSequence getTransformation(CharSequence source, View view) {
        return new PasswordCharSequence(source);
    }

    private class PasswordCharSequence implements CharSequence {

        private CharSequence mSource;

        public PasswordCharSequence(CharSequence source) {
            mSource = source; 
        }

        public char charAt(int index) {
            return '.'; 
        }

        public int length() {
            return mSource.length(); 
        }

        public CharSequence subSequence(int start, int end) {
            return mSource.subSequence(start, end); // Return default
        }
    }
};

实现是这样的，

passwordEditText = (EditText) findViewById(R.id.passwordEditText);
passwordEditText.setTransformationMethod(new MyPasswordTransformationMethod());