Question

我目前有一个工作if语句，但如果用户输入三个字段中的任何一个，他们可以发送数据我如何获得if else语句，所以除非填写所有三个字段，否则无法发送数据。

class MainActivity : AppCompatActivity() {

    var editText: EditText? = null
    var editText2: EditText? = null;
    var editText3: EditText? = null;

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

        editText = findViewById<EditText>(R.id.editText)
        editText2 = findViewById<EditText>(R.id.editText2)
        editText3 = findViewById<EditText>(R.id.editText3)
    }


    /** Called when the user taps the Send button */
    fun sendMessage(view: View) {


        if (editText!!.text.toString().length == 0) {
            Toast.makeText(this, "You did not enter your name", Toast.LENGTH_SHORT).show();

            if (editText2!!.text.toString().length == 0)
                Toast.makeText(this, "You did not enter a email address", Toast.LENGTH_SHORT).show();

            if (editText3!!.text.toString().length == 0)
                Toast.makeText(this, "You did not enter a comapny name", Toast.LENGTH_SHORT).show();
            return;
        }else if {

            val message1 = editText!!.text.toString()
            val message2 = editText2!!.text.toString()
            val message3 = editText3!!.text.toString()

            val intent = Intent(this, DisplayMessageActivity::class.java).apply {
                putExtra("EXTRA_MSG1", message1)
                putExtra("EXTRA_MSG2", message2)
                putExtra("EXTRA_MSG3", message3)

            }

            startActivity(intent)
        }
    }
}

Answer 1

您可以使用when声明。我已经创建了几个扩展函数来使代码更具可读性：

fun TextView?.getText(): String = this?.text?.toString() ?: ""

fun TextView?.isEmpty(): Boolean = this?.text?.isEmpty() ?: false

fun showToast(msg: String) {
    Toast.makeText(this, msg, Toast.LENGTH_SHORT).show()
}

fun sendMessage(view: View) {
    when {
        editText.isEmpty() -> showToast("You did not enter your name")
        editText2.isEmpty() -> showToast("You did not enter a email address")
        editText3.isEmpty() -> showToast("You did not enter a comapny name")
        else -> openActivity()
    }
}

fun openActivity() {
    val intent = Intent(this, DisplayMessageActivity::class.java).apply {
        putExtra("EXTRA_MSG1", editText.getText())
        putExtra("EXTRA_MSG2", editText2.getText())
        putExtra("EXTRA_MSG3", editText3.getText())
    }

    startActivity(intent)
}

我还建议您将EditText声明更改为lateinit var，以免处理这些可空性检查：

lateinit var editText: EditText
lateinit var editText2: EditText
lateinit var editText3: EditText

Answer 2

试试这段代码..

fun sendMessage(view:View) {


    if (TextUtils.isEmpty(editText !!.text.toString())){
        Toast.makeText(this, "You did not enter your name", Toast.LENGTH_SHORT).show();
    }
    if (TextUtils.isEmpty(editText2 !!.text.toString())){
        Toast.makeText(this, "You did not enter a email address", Toast.LENGTH_SHORT).show();
    }
    if (TextUtils.isEmpty(editText3 !!.text.toString())){
        Toast.makeText(this, "You did not enter a comapny name", Toast.LENGTH_SHORT).show();
    }
    if (TextUtils.isEmpty(editText !!.text.toString())&&TextUtils.isEmpty(editText2 !!.
    text.toString())&&TextUtils.isEmpty(editText3 !!.text.toString())){
        val message1 = editText !!.text.toString()
        val message2 = editText2 !!.text.toString()
        val message3 = editText3 !!.text.toString()

        val intent = Intent(this, DisplayMessageActivity:: class.java).apply {
            putExtra("EXTRA_MSG1", message1)
            putExtra("EXTRA_MSG2", message2)
            putExtra("EXTRA_MSG3", message3)

        }

        startActivity(intent)
    }
}

Answer 3

您可以使用一个简短的函数来验证输入的数据，如

  fun TextView.isEmpty():Boolean{
     return this?.text?.isEmpty()
    }

    fun showMessage(msg:String){
     //show some message here
     Toast.makeText(this, msg, Toast.LENGTH_SHORT).show()
    }

    fun openActivity(m1:String="",m2:String="",m3:String=""){
     val intent = Intent(this, DisplayMessageActivity:: class.java).apply {
                putExtra("EXTRA_MSG1", m1)
                putExtra("EXTRA_MSG2", m2)
                putExtra("EXTRA_MSG3", m3)
            }
     startActivity(intent)
    }

    fun valid(){
     if(editText.isEmpty() or editText1.isEmpty() or editText2.isEmpty()){
       showMessage()
     }else{
       openActivity()  
     }
    }

Answer 4

我使用TextUtils.isEmpty（）。根据文档，如果字符串为null或长度为零，则返回true。

https://developer.android.com/reference/android/text/TextUtils#isEmpty(java.lang.CharSequence)

kotlin if else声明

4 个答案: