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Accepted
Stas
Asked:2020-06-28 16:59:57 +0800 CST2020-06-28 16:59:57 +0800 CST

键盘事件

  • 772

我是 Kotlin 的新手，当用户在 EditText 字段中键入内容时，我对如何捕获事件感到有些困惑？例如，如何确保当用户输入某些内容并在 TextView 中复制它？

android

3 个回答

  1. 有一个文本更改侦听器addTextChangedListener：

    EditText editText = (EditText) findViewById(R.id.editText);
editText.addTextChangedListener(new TextWatcher() {
 
    public void afterTextChanged(Editable s) {}
 
    public void beforeTextChanged(CharSequence s, int start,int count, int after) {
    }
 
    public void onTextChanged(CharSequence s, int start, int before, int count) {
      TextView textView = (TextView) findViewById(R.id.textView);
      textView.setText(s);
    }
});

    这是您问题的教程。

    UPDATE_KOTLIN

    val editText: EditText = findViewById(R.id.editText)
editText.addTextChangedListener(object :TextWatcher{
   override fun afterTextChanged(p0: Editable?) {
                
   }

   override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
                
   }

   override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
    val textView = findViewById<View>(R.id.textView) as TextView
    textView.text = s
   }

})
    • 1
  2. Best Answer

    我认为这会帮助你：

    class MainActivity:AppCompatActivity() {

overridefunonCreate(savedInstanceState:
Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    editTextSample.addTextChangedListener(object:TextWatcher{

        overridefunafterTextChanged(s:Editable) {}

        overridefunbeforeTextChanged(s:CharSequence, start:Int,count:Int, after:Int) {}

overridefunonTextChanged(s:CharSequence,start:Int,before:Int, count:Int){
tvSample.setText("Text in EditText : "+s)
        
}
    
})

}
}
    • 1

  3. 由于你使用的是kotlin，所以我推荐使用ktx
    首先，添加依赖到gradle

    android {
      ...
    compileOptions {
    sourceCompatibility 1.8
    targetCompatibility 1.8
}
kotlinOptions {
    jvmTarget = JavaVersion.VERSION_1_8.toString()
}
}
dependencies {
... 
implementation 'androidx.core:core-ktx:1.3.0'
}

    之后，您可以在代码中使用更简单的结构

    editText.doOnTextChanged  { text, start, count, after -> 
       
    }
    • 1

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