使用下面的代码

    val hidePasswordMethod = PasswordTransformationMethod()
    showOrHidePasswordButton.setOnClickListener {
        passwordEditText.apply {
            transformationMethod =
                if (transformationMethod is PasswordTransformationMethod) 
                   null //shows password
               else 
                   hidePasswordMethod //hides password
        }
    }

并确保你把它添加到你的密码编辑文本在布局

    android:inputType="textPassword"

我也遇到过同样的问题，而且它很容易实现。

你所要做的就是在一个(com.google.android.material.textfield.TextInputLayout)和添加(app:passwordToggleEnabled="true")中包装你的EditText字段。

这将在EditText字段中显示眼睛，当您单击它时，密码将出现并在再次单击时消失。

<com.google.android.material.textfield.TextInputLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:textColorHint="#B9B8B8"
                app:passwordToggleEnabled="true">

                <EditText
                    android:id="@+id/register_password"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginLeft="24dp"
                    android:layout_marginRight="44dp"
                    android:backgroundTint="#BEBEBE"
                    android:hint="Password"
                    android:inputType="textPassword"
                    android:padding="16dp"
                    android:textSize="18sp" />
            </com.google.android.material.textfield.TextInputLayout>

根据这个来源，如果你已经将你的项目迁移到AndroidX，那么你可以替换

编译”com.android.support:设计:24.2.0”

与

实现“com.google.android.material:材料:1.0.0”

然后你所要做的就是把下面的代码放到你的布局文件中:

<com.google.android.material.textfield.TextInputLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:passwordToggleEnabled="true"
    android:hint="@string/hint_text">

  <com.google.android.material.textfield.TextInputEditText
      android:layout_width="match_parent"
      android:layout_height="wrap_content"/>

</com.google.android.material.textfield.TextInputLayout>

关于材质TextInputLayout的更多信息可以在这里找到。

对于这个源码，建议从Android支持库迁移到AndroidX:

AndroidX is the open-source project that the Android team uses to develop, test, package, version and release libraries within Jetpack. AndroidX is a major improvement to the original Android Support Library. Like the Support Library, AndroidX ships separately from the Android OS and provides backwards-compatibility across Android releases. AndroidX fully replaces the Support Library by providing feature parity and new libraries. In addition AndroidX includes the following features: All packages in AndroidX live in a consistent namespace starting with the string androidx. The Support Library packages have been mapped into corresponding androidx.* packages. For a full mapping of all the old classes and build artifacts to the new ones, see the Package Refactoring page. Unlike the Support Library, AndroidX packages are separately maintained and updated. The androidx packages use strict Semantic Versioning starting with version 1.0.0. You can update AndroidX libraries in your project independently. All new Support Library development will occur in the AndroidX library. This includes maintenance of the original Support Library artifacts and introduction of new Jetpack components.

只需在Xml文件中创建一个复选框

然后简单的用Java代码编写这个函数

checkbox = findViewById(R.id.checkbox);
        checkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener(){
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked){

                if (isChecked) {
                    password.setTransformationMethod(null);
                }
                else{
                    password.setTransformationMethod(new PasswordTransformationMethod());
                }
            }

        });

你可以使用app:passwordToggleEnabled="true"

下面是一个例子

<android.support.design.widget.TextInputLayout
        android:id="@+id/password"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:passwordToggleEnabled="true"
        android:textColorHint="@color/colorhint"
        android:textColor="@color/colortext">

我使用了一个OnClickListener()，它与我想用作toogle的按钮相关联。

private EditText email_et, contraseña_et;
protected void onCreate(Bundle savedInstanceState) {
....
contraseña_et = (EditText) findViewById(R.id.contraseña_et);
....
vercontra_btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            int inputType = contraseña_et.getInputType();
            if (inputType == 129){
                contraseña_et.setInputType(1);
            } else {
                contraseña_et.setInputType(129);
            }
            contraseña_et.setSelection(contraseña_et.getText().length());
        }
    });

阅读文档，int值似乎是不同的，所以我调试找到正确的值，它的工作棒极了，这是一个更容易一点的方式。

[顺便说一下，Contraseña是西班牙语的密码]