I made four simple buttons. When the user clicks the button, Toast (pop up message) comes out. The sentence showing up is 'Button is clicked'

I want to modify the text to follow this form. 'The $num button is clicked'

actual result

Here is my kotlin file code

package com.example.mycalculator_chapter7

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Toast

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

    fun onDigit(view: View, num:Int) {
        Toast.makeText(this, "$num Button is clicked", Toast.LENGTH_LONG).show()

    }
}

Here is my activity_main xml file code

<LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        >
        <Button
            android:id="@ id/btnSeven"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_margin="2dp"
            android:text="@string/buttonSeven"
            android:onClick="onDigit(7)"
            tools:ignore="OnClick,UsingOnClickInXml"/>
        <Button
            android:id="@ id/btnEight"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_margin="2dp"
            android:text="@string/buttonEight"
            android:onClick="onDigit(8)"
            tools:ignore="OnClick,UsingOnClickInXml"/>
        <Button
            android:id="@ id/btnNine"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_margin="2dp"
            android:text="@string/buttonNine"
            android:onClick="onDigit(9)"
            tools:ignore="OnClick,UsingOnClickInXml"/>
        <Button
            android:id="@ id/btnDivide"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_margin="2dp"
            android:text="@string/buttonZero"
            android:onClick="onDigit(0)"
            tools:ignore="OnClick,UsingOnClickInXml" />
    </LinearLayout>

question i know that using onClickEventListener is better than using onClick, but i want to know how to deliver the numeric value to method 'onDigit' in Class, showing the result of the number.

CodePudding user response：

You have the number inside the button, so just use it
e.g:

Button btnSeven = findViewById(R.id.btnSeven)

btnSeven.setOnClickListener { 
     val msg = "${btnSeven.text} Button is clicked"
     Toast.makeText(this, msg, Toast.LENGTH_LONG).show()
}

CodePudding user response：

Solution 1 with onClick: This code will do what you want, I add a check to make sure that the View is a Button so I can have access to the text of the button, then I get the num from the text of the button and convert it to string: val num = view.text.toString()

package com.example.mycalculator_chapter7

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Toast

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

    fun onDigit(view: View) {
        if (view !is Button) return
        val num = view.text.toString()
        Toast.makeText(this, "$num Button is clicked", Toast.LENGTH_LONG).show()
    }
}

Solution 2 with setOnClickListener: This is the best way to add on click events, first you need to remove all onClick lines from xml, then add click listener to each button by kotlin:

package com.example.mycalculator_chapter7

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Toast

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

        btnSeven.setOnClickListener { onDigit(7) }
        btnEight.setOnClickListener { onDigit(8) }
        btnNine.setOnClickListener { onDigit(9) }
    }

    fun onDigit(num: Int) {
        Toast.makeText(this, "$num Button is clicked", Toast.LENGTH_LONG).show()
    }
}