您如何检查EditText是否为空?输入类型编号
package com.example.www.myapplication
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_main.*
import java.util.*
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
button.setOnClickListener {
val inter:Int=editText.text.toString().toInt()
val year: Int = Calendar.getInstance().get(Calendar.YEAR)
val res:Int=year-inter
textView.text=res.toString()
}
}
这是带有解释的完整示例。
//init the edittext
val etMessage = findViewById(R.id.et_message) as EditText
//init the button
val btnClick = findViewById(R.id.btn_click) as Button
btnClick.setOnClickListener{
//read value from EditText to a String variable
val msg: String = etMessage.text.toString()
//check if the EditText have values or not
if(msg.trim().length>0) {
Toast.makeText(applicationContext, "Message : "+msg, Toast.LENGTH_SHORT).show()
}else{
Toast.makeText(applicationContext, "Please enter some message! ", Toast.LENGTH_SHORT).show()
}
}
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