Java正常运行时，Kotlin在PasswordTransformationMethod中崩溃

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问题描述

下面的代码在Kotlin/Android中崩溃，底部提供了堆栈跟踪.它是从Java/Android转换而来的，它没有这样的问题.还提供了原始Java代码.当我尝试将字符添加到密码字段时，发生崩溃.编辑现有字符效果很好.

The code below crashes in Kotlin/Android with the stack trace provided on the bottom. It was converted from Java/Android, which didn't have such a problem. Original Java code is provided as well. The crash happens when I try to add a character to a password field. Editing existing characters works well.

对此我有两个问题:

Kotlin用Kotlin的CharSequence替换java.lang.CharSequence的动机是什么?这两个是完全不同的，我怀疑这会导致崩溃.
有什么办法可以使其在Kotlin中工作?

科特琳代码使Android的Paint崩溃

        mPwd!!.transformationMethod = object : PasswordTransformationMethod() {
        override fun getTransformation(source: CharSequence, view: View): CharSequence {
            return PasswordCharSequence(source)
        }
        internal inner class PasswordCharSequence(private val source: CharSequence)// Store char sequence
            : CharSequence {

            val mSource = source
            public override val length = mSource.length

            init {
                App.d(TAG, "SOURCE " + mSource + " " + length)
            }
            override fun get(index: Int): Char {
                App.d(TAG, "SOURCE IND " + index + " " + mSource.length)
                return if (mChkUnmask!!.isChecked) mSource.get(index) else '*'
            }
            override fun subSequence(start: Int, end: Int): CharSequence {
                App.d(TAG, "SOURCE SUB " + start + " " + end)
                return mSource.subSequence(start, end) // Return default
            }
        }
    }

效果很好的原始Java代码

        mPwd.setTransformationMethod(new PasswordTransformationMethod() {

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

        class PasswordCharSequence implements CharSequence {
            private CharSequence mSource;
            public PasswordCharSequence(CharSequence source) {
                mSource = source; // Store char sequence
            }
            public char charAt(int index) {
                return mChkUnmask.isChecked()?mSource.charAt(index):'*';
            }
            public int length() {
                return mSource.length(); // Return default
            }
            public CharSequence subSequence(int start, int end) {
                return mSource.subSequence(start, end); // Return default
            }
        }
    });

来自Logcat的堆栈跟踪

06-03 00:35:08.143 16694 16694 E AndroidRuntime: java.lang.IndexOutOfBoundsException
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.graphics.Paint.getRunAdvance(Paint.java:2986)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.text.TextLine.handleText(TextLine.java:719)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.text.TextLine.handleRun(TextLine.java:873)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.text.TextLine.measureRun(TextLine.java:387)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.text.TextLine.measure(TextLine.java:277)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.text.TextLine.metrics(TextLine.java:251)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.text.Layout.getLineExtent(Layout.java:1072)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.text.Layout.getLineWidth(Layout.java:1038)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.widget.TextView.desired(TextView.java:8142)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.widget.TextView.onMeasure(TextView.java:8208)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.view.View.measure(View.java:21051)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.view.View.measure(View.java:21051)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.view.View.measure(View.java:21051)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6459)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:141)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.view.View.measure(View.java:21051)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6459)
06-03 00:35:08.143 16694 16694 E AndroidRuntime:        at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:400)

Log.d(...)的程序输出

10是此处的CharSequence长度.第一位-当前索引.当我尝试通过键盘添加索引为9的字符时发生崩溃.从未添加过它，也没有出现在

10 is a CharSequence length here. First digit - current index. Crash happens when I was trying to add a char with index 9 from a keyboard. It was never added and didn't show up in the output below

06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 810
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 710
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 610
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 510
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 410
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 310
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 210
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 110
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 010
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 010
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 110
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 210
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 310
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 410
06-03 00:35:08.121 16694 16694 D GAC-STORE: SOURCE IND 510
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 610
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 710
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 810
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 010
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 110
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 210
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 310
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 410
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 510
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 610
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 710
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 810
06-03 00:35:08.122 16694 16694 D GAC-STORE: SOURCE IND 810

mPwd的布局

<EditText
    android:id="@+id/txtDlgPwd"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/chkStorePwd"
    android:hint ="Ecnryption Password"
    android:maxLines="1"
    android:singleLine="true"
    android:inputType="textPassword|textNoSuggestions"
    android:imeOptions="actionDone"
    android:layout_marginLeft="10dp"
    android:layout_marginTop="20dp"
    android:textSize="15sp"/>

推荐答案

幸运的是，Android/Kotlin允许在单个项目中混合Java和Kotlin文件.我用它来解决问题.

Fortunately, Android/Kotlin allows mixing Java and Kotlin files in a single project. I used this as a work around for the problem.

创建了一个用于处理密码的Java类.请注意，CharSequence在这里是本机Java类，这有所作为.

Created a Java class for the password handling. Please notice, CharSequence is a native Java class here, and this makes a difference.

import java.lang.CharSequence;

public class PasswordHandler implements CharSequence {

    private CharSequence mSource;
    private Switch mUnmask;

    public PasswordHandler(CharSequence source, Switch unmask) {
        mSource = source;
        mUnmask = unmask;
    }

    public char charAt(int index) {
        return mUnmask.isChecked()?mSource.charAt(index):'*';
    }
    public int length() {
        return mSource.length();
    }
    public CharSequence subSequence(int start, int end) {
        return mSource.subSequence(start, end);
    }

    @NonNull
    @Override
    public String toString() {
        String star = new String();
        int l = length();
        if (!mUnmask.isChecked()) {
            while (l-- > 0){
                star += "*";
            }
        }
        return mUnmask.isChecked()? mSource.toString():star;
    }
}

在Kotlin的类中的getTransfromation方法中实例化了该类. Kotlin编译器这次表现良好.崩溃不再发生了.我仍然希望看到纯Kotlin的解决方案.

Instantiated this class in getTransfromation method in a Kotlin's class. Kotlin compiler took it well this time. Crashes do not happen anymore.I still would like to see a pure Kotlin's solution for this.

mPwd!!.transformationMethod = object : PasswordTransformationMethod() {
            override fun getTransformation(source: CharSequence, view: View): CharSequence {
                return PasswordHandler(source, mChkUnmask)
            }

        }

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