android - 无法解决 MainActivityBinding 以及绑定(bind)相关问题

Question

我想做一个科学计算器。

我在这个网站上找到了一些有用的代码:http://www.androidauthority.com/build-a-calculator-app-721910/

然后我根据自己的目的修改了它。在此代码中，我发现使用了绑定(bind)方法，因此我按照本网站上的说明在我的 IDE 中进行了以下更改:https://developer.android.com/topic/libraries/data-binding/index.html

我对 build.gradle(module app) 进行了更改并且还对我的 MainActivity.java 代码进行了更改。

但是出现了以下错误:

MainActivity.java

package com.example.anant.scientificcalculator;

import android.databinding.DataBindingUtil;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import static java.lang.Math.*;
import java.text.DecimalFormat;
//import com.example.anant.scientificcalculator.databinding.MainActivityBinding;
//import android.content.DialogInterface;
//import android.text.TextUtils;
//import android.view.View;
//import android.widget.Button;
//import android.widget.EditText;
//import android.widget.TextView;


public class MainActivity extends AppCompatActivity {

private MainActivityBinding binding; //error in this line cannot resolve MainActivityBinding.

private static final char FACT = '!';
private static final char POWER = '^';
private static final String SQRT = "SQRT";

private static final String SIN = "SIN";
private static final String COS = "COS";
private static final String TAN = "TAN";
private static final String LOG = "LOG";

private static final char LEFTC = '(';
private static final char RIGHTC = ')';
private static final String EXP = "EXP";
private static final String PIE = "PIE";

private static final char ADD = '+';
private static final char SUBTRACT = '-';
private static final char MULTIPlY = '*';
private static final char DIVIDE = '/';

private char CURRENT_ACTION;
private String ADVANCE_ACTION;

private double valueOne = Double.NaN;
private double valueTwo;

private DecimalFormat decimalFormat;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    decimalFormat = new DecimalFormat("#.##########");

    MainActivityBinding binding = DataBindingUtil.setContentView(this, R.layout.main_activity);

   //error in all the lines below saying cannot resolve button-----(where ---- denotes the specific terms of the button)

    binding.buttonDot.setOnClickListener(new View.OnClickListener(){
        @Override
                public void onClick(View view){
                    binding.editText.setText(binding.editText.getText() + ".");
        }
    });

    binding.buttonZero.setOnCLickListener(new View.OnClickListener(){
        @Override
            public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "0");
        }
    });

    binding.buttonOne.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "1");
        }
    });

    binding.buttonTwo.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "2");
        }
    });

    binding.buttonThree.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "3");
        }
    });

    binding.buttonFour.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "4");
        }
    });

    binding.buttonFive.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "5");
        }
    });

    binding.buttonSix.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "6");
        }
    });

    binding.buttonSeven.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "7");
        }
    });

    binding.buttonEight.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "8");
        }
    });

    binding.buttonNine.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "9");
        }
    });

    binding.buttonLeftC.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + "(");
        }
    });

    binding.buttonRightC.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            binding.editText.setText(binding.editText.getText() + ")");
        }
    });

    binding.buttonExp.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            computeCalculation();
            ADVANCE_ACTION = EXP;
            binding.infoTextView.setText(decimalFormat.format(valueOne) + "EXP");
            binding.editText.setText(null);
        }
    });

    binding.buttonPie.setOnCLickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            computeCalculation();
            ADVANCE_ACTION = PIE;
            binding.infoTextView.setText(decimalFormat.format(valueOne) + "PIE");
            binding.editText.setText(null);
        }
    });

    binding.buttonAdd.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            CURRENT_ACTION = ADD;
            binding.infoTextView.setText(decimalFormat.format(valueOne) + "+");
            binding.editText.setText(null);
        }
    });

    binding.buttonSubtract.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            CURRENT_ACTION = SUBTRACT;
            binding.infoTextView.setText(decimalFormat.format(valueOne) + "-");
            binding.editText.setText(null);
        }
    });

    binding.buttonMultiply.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            CURRENT_ACTION = MULTIPlY;
            binding.infoTextView.setText(decimalFormat.format(valueOne) + "*");
            binding.editText.setText(null);
        }
    });

    binding.buttonDivide.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            CURRENT_ACTION = DIVIDE;
            binding.infoTextView.setText(decimalFormat.format(valueOne) + "/");
            binding.editText.setText(null);
        }
    });

    binding.buttonFact.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            CURRENT_ACTION = FACT;
            binding.infoTextView.setText(decimalFormat.format(valueOne) + "!");
            binding.editText.setText(null);
        }
    });

    binding.buttonPow.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            CURRENT_ACTION = POWER;
            binding.infoTextView.setText(decimalFormat.format(valueOne) + "^");
            binding.editText.setText(null);
        }
    });

    binding.buttonSqrt.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            ADVANCE_ACTION = SQRT;
            binding.infoTextView.setText("SQRT(" + decimalFormat.format(valueOne) + ")");
            binding.editText.setText(null);
        }
    });

    binding.buttonSine.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            ADVANCE_ACTION = SIN;
            binding.infoTextView.setText("SIN(" + decimalFormat.format(valueOne) + ")");
            binding.editText.setText(null);
        }
    });

    binding.buttonCosine.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            ADVANCE_ACTION = COS;
            binding.infoTextView.setText("COS(" + decimalFormat.format(valueOne) + ")");
            binding.editText.setText(null);
        }
    });

    binding.buttonTangent.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            ADVANCE_ACTION = TAN;
            binding.infoTextView.setText("TAN(" + decimalFormat.format(valueOne) + ")");
            binding.editText.setText(null);
        }
    });

    binding.buttonLog.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            ADVANCE_ACTION = LOG;
            binding.infoTextView.setText("LOG(" + decimalFormat.format(valueOne) + ")");
            binding.editText.setText(null);
        }
    });

    binding.buttonEqual.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            computeCalculation();
            binding.infoTextView.setText(binding.infoTextView.getText().toString() +
                    decimalFormat.format(valueTwo) + " = " + decimalFormat.format(valueOne));
            valueOne = Double.NaN;
            CURRENT_ACTION = '0';
        }
    });

    binding.buttonClear.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            if(binding.editText.getText().length() > 0) {
                CharSequence currentText = binding.editText.getText();
                binding.editText.setText(currentText.subSequence(0, currentText.length()-1));
            }
            else {
                valueOne = Double.NaN;
                valueTwo = Double.NaN;
                binding.editText.setText("");
                binding.infoTextView.setText("");
            }
        }
    });

}

private void computeCalculation() {
    if(!Double.isNaN(valueOne)) {
        valueTwo = Double.parseDouble(binding.editText.getText().toString());
        binding.editText.setText(null);

        if(CURRENT_ACTION == ADD)
            valueOne = this.valueOne + valueTwo;
        else if(CURRENT_ACTION == SUBTRACT)
            valueOne = this.valueOne - valueTwo;
        else if(CURRENT_ACTION == MULTIPlY)
            valueOne = this.valueOne * valueTwo;
        else if(CURRENT_ACTION == DIVIDE)
            valueOne = this.valueOne / valueTwo;
        else if(CURRENT_ACTION == FACT)
        {
            int i,valueThree = 1;
            for(i=(int) valueOne;i>0;i--) //type conversion
            {
                valueThree *= i;
            }
        }
        else if(CURRENT_ACTION == POWER)
            valueOne = Math.pow(valueOne,valueTwo);
        else if(ADVANCE_ACTION == SQRT)
            valueOne = Math.sqrt(valueOne);
        else if(ADVANCE_ACTION == SIN)
            valueOne = Math.sin(valueOne);
        else if(ADVANCE_ACTION == COS)
            valueOne = Math.cos(valueOne);
        else if(ADVANCE_ACTION == TAN)
            valueOne = Math.tan(valueOne);
        else if(ADVANCE_ACTION == LOG)
            valueOne = Math.log(valueOne);
        else if(ADVANCE_ACTION == PIE)
            valueOne = Math.PI;
        else if(ADVANCE_ACTION == EXP)
            valueOne = Math.E;
    }
    else {
        try {
            valueOne = Double.parseDouble(binding.editText.getText().toString());
        }
        catch (Exception e){}
    }
}

这是我的xml文件

ma​​in_activity.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_activity"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.anant.scientificcalculator.MainActivity">


<TextView
    android:id="@+id/infoTextView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginBottom="30dp"
    android:textSize="30sp" />

<EditText
    android:id="@+id/editText"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@id/infoTextView"
    android:enabled="false"
    android:gravity="bottom"
    android:hint="0"
    android:inputType="numberDecimal"
    android:lines="2"
    android:maxLines="2"
    android:textAlignment="textEnd"
    android:textColor="@android:color/black"
    android:textSize="40sp" />

<Button
    android:id="@+id/buttonFact"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/editText"
    android:text="@string/buttonFact"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonPow"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/editText"
    android:layout_toRightOf="@id/buttonFact"
    android:text="@string/buttonPow"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonSqrt"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/editText"
    android:layout_toRightOf="@id/buttonPow"
    android:text="@string/buttonSqrt"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonClear"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_toRightOf="@id/buttonSqrt"
    android:layout_below="@id/editText"
    android:text="@string/buttonClear"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonSine"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonFact"
    android:text="@string/buttonSine"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonCosine"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonPow"
    android:layout_toRightOf="@id/buttonSine"
    android:text="@string/buttonCosine"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonTangent"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonSqrt"
    android:layout_toRightOf="@id/buttonCosine"
    android:text="@string/buttonTangent"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonLog"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonClear"
    android:layout_toRightOf="@id/buttonTangent"
    android:text="@string/buttonLog"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonLeftC"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonSine"
    android:text="@string/buttonLeftC"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonRightC"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonCosine"
    android:layout_toRightOf="@id/buttonLeftC"
    android:text="@string/buttonRightC"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonExp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonTangent"
    android:layout_toRightOf="@id/buttonRightC"
    android:text="@string/buttonExp"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonPie"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonLog"
    android:layout_toRightOf="@id/buttonExp"
    android:text="@string/buttonPie"
    android:textSize="20sp" />


<Button
    android:id="@+id/buttonSeven"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonLeftC"
    android:text="@string/buttonSeven"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonEight"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonRightC"
    android:layout_toRightOf="@id/buttonSeven"
    android:text="@string/buttonEight"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonNine"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonExp"
    android:layout_toRightOf="@id/buttonEight"
    android:text="@string/buttonNine"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonFour"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonSeven"
    android:text="@string/buttonFour"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonFive"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonEight"
    android:layout_toRightOf="@id/buttonFour"
    android:text="@string/buttonFive"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonSix"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonNine"
    android:layout_toRightOf="@id/buttonFive"
    android:text="@string/buttonSix"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonOne"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonFour"
    android:text="@string/buttonOne"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonTwo"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonFive"
    android:layout_toRightOf="@id/buttonOne"
    android:text="@string/buttonTwo"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonThree"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonSix"
    android:layout_toRightOf="@id/buttonTwo"
    android:text="@string/buttonThree"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonDot"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonOne"
    android:text="@string/buttonDot"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonZero"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/buttonTwo"
    android:layout_toRightOf="@id/buttonDot"
    android:text="@string/buttonZero"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonEqual"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignRight="@id/buttonNine"
    android:layout_below="@id/buttonThree"
    android:text="@string/buttonEqual"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonDivide"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@id/buttonNine"
    android:layout_toRightOf="@id/buttonNine"
    android:text="@string/buttonDIvide"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonMultiply"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@id/buttonSix"
    android:layout_toRightOf="@id/buttonSix"
    android:text="@string/buttonMultiply"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonSubtract"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@id/buttonThree"
    android:layout_toRightOf="@id/buttonThree"
    android:text="@string/buttonSubtract"
    android:textSize="20sp" />

<Button
    android:id="@+id/buttonAdd"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignTop="@id/buttonEqual"
    android:layout_toRightOf="@id/buttonEqual"
    android:text="@string/buttonAdd"
    android:textSize="20sp" />

</RelativeLayout>

Answer 1

您需要取消注释:

//import com.example.anant.scientificcalculator.databinding.MainActivityBinding;

这是为您的数据绑定(bind)自动生成的类。你需要它。让它看起来像这样:

com.example.anant.scientificcalculator.databinding.MainActivityBinding;

其次，您的 XML 文件不正确，它应该将其 RelativeLayout 包裹在 layout 标记中，如下所示:

<layout>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_activity"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.anant.scientificcalculator.MainActivity">
...
</layout>

在你这样做之后，进行清理和重建，我认为你应该可以开始了。