如何仅在EditText填写完成或被触摸时显示drawableRight图标

前置步骤：初始化隐藏右侧图标 #

你布局中已经给EditText配置了右侧图标资源，首先在Activity/Fragment初始化阶段先把图标隐藏：

// Kotlin代码
val mobileEt = findViewById<EditText>(R.id.mobiledes)
// 四个参数分别对应左、上、右、下位置的drawable，设为0即隐藏对应位置图标
mobileEt.setCompoundDrawablesWithIntrinsicBounds(0, 0, 0, 0)

// Java代码
EditText mobileEt = findViewById(R.id.mobiledes);
mobileEt.setCompoundDrawablesWithIntrinsicBounds(0, 0, 0, 0);

方案1：输入满10位数字时显示右侧图标 #

给EditText添加文本变化监听器，判断输入长度控制图标显隐：

// Kotlin代码
mobileEt.addTextChangedListener(object : TextWatcher {
    override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}
    override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {}
    override fun afterTextChanged(s: Editable?) {
        s?.let {
            if (it.length == 10) {
                // 输入长度达标，显示右侧图标
                mobileEt.setCompoundDrawablesWithIntrinsicBounds(0, 0, R.drawable.ic_verifybutton, 0)
            } else {
                // 输入长度不足，隐藏图标
                mobileEt.setCompoundDrawablesWithIntrinsicBounds(0, 0, 0, 0)
            }
        }
    }
})

// Java代码
mobileEt.addTextChangedListener(new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {}
    @Override
    public void afterTextChanged(Editable s) {
        if (s.length() == 10) {
            mobileEt.setCompoundDrawablesWithIntrinsicBounds(0, 0, R.drawable.ic_verifybutton, 0);
        } else {
            mobileEt.setCompoundDrawablesWithIntrinsicBounds(0, 0, 0, 0);
        }
    }
});

方案2：EditText被触摸时就显示右侧图标 #

给EditText添加触摸监听器，触摸时显示图标，可搭配焦点监听实现失去焦点后自动隐藏：

// Kotlin代码
// 触摸时显示图标
mobileEt.setOnTouchListener { _, event ->
    if (event.action == MotionEvent.ACTION_DOWN) {
        mobileEt.setCompoundDrawablesWithIntrinsicBounds(0, 0, R.drawable.ic_verifybutton, 0)
    }
    // 返回false不消费触摸事件，不影响EditText原生交互逻辑
    false
}

// 可选配置：失去焦点后隐藏图标
mobileEt.setOnFocusChangeListener { _, hasFocus ->
    if (!hasFocus) {
        mobileEt.setCompoundDrawablesWithIntrinsicBounds(0, 0, 0, 0)
    }
}

// Java代码
// 触摸时显示图标
mobileEt.setOnTouchListener(new View.OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            mobileEt.setCompoundDrawablesWithIntrinsicBounds(0, 0, R.drawable.ic_verifybutton, 0);
        }
        return false;
    }
});

// 可选配置：失去焦点后隐藏图标
mobileEt.setOnFocusChangeListener(new View.OnFocusChangeListener() {
    @Override
    public void onFocusChange(View v, boolean hasFocus) {
        if (!hasFocus) {
            mobileEt.setCompoundDrawablesWithIntrinsicBounds(0, 0, 0, 0);
        }
    }
});

可选优化：自定义图标显示大小 #

如果默认显示的图标尺寸不符合预期，可以手动调整drawable大小后再设置：

val drawable = ContextCompat.getDrawable(this, R.drawable.ic_verifybutton)
// 按需求调整图标大小，示例为24dp，需自行实现dp转px的工具方法
drawable?.setBounds(0, 0, dp2px(24), dp2px(24))
mobileEt.setCompoundDrawables(null, null, drawable, null)

内容的提问来源于stack exchange，提问作者Kumar Harsh