Question

当我将全局变量声明为double并赋值时，它返回一个整数值。

使用调试模式，我发现编译器使用整数值而不是浮点来初始化变量，如图所示。

编辑：

好的，这是整个代码==

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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.ommabdelhafiz.amathmess.MainActivity">
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:padding="16dp"
            android:orientation="vertical">











            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal">

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="7"
                    android:textSize="16sp"
                    android:id="@+id/first_1st"/>

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="×"
                    android:textSize="16sp"
                    />

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="7"
                    android:textSize="16sp"
                    android:id="@+id/first_2nd"/>

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="="
                    android:textSize="16sp"
                    />

                <EditText
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textSize="16sp"
                    android:inputType="number"
                    android:maxLength="3"
                    android:hint="                "
                    android:id="@+id/first_ans"
                    android:imeOptions="actionDone"
                    android:layout_marginRight="20dp"/>








                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="0"
                        android:textSize="16dp"
                        android:layout_gravity="center_horizontal"
                        android:id="@+id/first_true_ans"/>

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="0"
                        android:textSize="16dp"
                        android:gravity="bottom"
                        android:layout_gravity="center_horizontal"
                        android:id="@+id/first_false_ans"/>

                </LinearLayout>

                <Button
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="Check"
                    android:layout_marginLeft="20dp"
                    android:onClick="check1st"
                    android:id="@+id/first_btn"/>

            </LinearLayout>






            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal">

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="49"
                    android:textSize="16sp"
                    android:id="@+id/second_1st"/>

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="÷"
                    android:textSize="16sp"
                    />

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="7"
                    android:textSize="16sp"
                    android:id="@+id/second_2nd"/>

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="="
                    android:textSize="16sp"
                    />

                <EditText
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textSize="16sp"
                    android:inputType="number"
                    android:maxLength="2"
                    android:hint="                "
                    android:id="@+id/second_ans"
                    android:imeOptions="actionDone"
                    android:layout_marginRight="20dp"/>









                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="0"
                        android:textSize="16dp"
                        android:layout_gravity="center_horizontal"
                        android:id="@+id/second_true_ans"/>

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="0"
                        android:textSize="16dp"
                        android:gravity="bottom"
                        android:layout_gravity="center_horizontal"
                        android:id="@+id/second_false_ans"/>

                </LinearLayout>

                <Button
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="Check"
                    android:layout_marginLeft="20dp"
                    android:onClick="check2nd"
                    android:id="@+id/second_btn"/>







            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal">

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="711"
                    android:textSize="16sp"
                    android:id="@+id/third_1st"/>

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="×"
                    android:textSize="16sp"
                    />

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="7"
                    android:textSize="16sp"
                    android:id="@+id/third_2nd"/>

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="="
                    android:textSize="16sp"
                    />

                <EditText
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textSize="16sp"
                    android:inputType="number"
                    android:maxLength="4"
                    android:hint="                "
                    android:id="@+id/third_ans"
                    android:imeOptions="actionDone"
                    android:layout_marginRight="20dp"/>








                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="0"
                        android:textSize="16dp"
                        android:layout_gravity="center_horizontal"
                        android:id="@+id/third_true_ans"/>

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="0"
                        android:textSize="16dp"
                        android:gravity="bottom"
                        android:layout_gravity="center_horizontal"
                        android:id="@+id/third_false_ans"/>

                </LinearLayout>

                <Button
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="Check"
                    android:layout_marginLeft="20dp"
                    android:onClick="check3rd"
                    android:id="@+id/third_btn"/>

            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal">

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="41.735"
                    android:textSize="16sp"
                    android:id="@+id/fourth_1st"/>

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="+"
                    android:textSize="16sp"
                    />

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="23.836"
                    android:textSize="16sp"
                    android:id="@+id/fourth_2nd"/>

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="="
                    android:textSize="16sp"
                    />

                <EditText
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textSize="16sp"
                    android:inputType="numberDecimal"
                    android:hint="                "
                    android:maxLength="7"
                    android:id="@+id/fourth_ans"
                    android:imeOptions="actionDone"
                    android:layout_marginRight="20dp"/>








                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="0"
                        android:textSize="16dp"
                        android:layout_gravity="center_horizontal"
                        android:id="@+id/fourth_true_ans"/>

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="0"
                        android:textSize="16dp"
                        android:gravity="bottom"
                        android:layout_gravity="center_horizontal"
                        android:id="@+id/fourth_false_ans"/>

                </LinearLayout>

                <Button
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="Check"
                    android:layout_marginLeft="20dp"
                    android:onClick="check4th"
                    android:id="@+id/fourth_btn"/>

            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal">

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="71.159"
                    android:textSize="16sp"
                    android:id="@+id/fifth_1st"/>

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="-"
                    android:textSize="16sp"
                    />

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="14.704"
                    android:textSize="16sp"
                    android:id="@+id/fifth_2nd"/>

                <TextView
                    android:layout_width="70dp"
                    android:layout_height="wrap_content"
                    android:text="="
                    android:textSize="16sp"
                    />

                <EditText
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textSize="16sp"
                    android:inputType="numberDecimal"
                    android:maxLength="7"
                    android:hint="                "
                    android:id="@+id/fifth_ans"
                    android:imeOptions="actionDone"
                    android:layout_marginRight="20dp"/>








                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="match_parent"
                    android:orientation="vertical">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="0"
                        android:textSize="16dp"
                        android:layout_gravity="center_horizontal"
                        android:id="@+id/fifth_true_ans"/>

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="0"
                        android:textSize="16dp"
                        android:gravity="bottom"
                        android:layout_gravity="center_horizontal"
                        android:id="@+id/fifth_false_ans"/>

                </LinearLayout>

                <Button
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="Check"
                    android:layout_marginLeft="20dp"
                    android:onClick="check5th"
                    android:id="@+id/fifth_btn"/>

            </LinearLayout>









        </LinearLayout>
    </ScrollView>
</RelativeLayout>

爪哇：

package com.example.ommabdelhafiz.amathmess;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.util.Random;

public class MainActivity extends AppCompatActivity {

    int firstTrueAns = 0;
    int firstFalseAns = 0;
    int firstFirstValue = 7;
    int firstSecondValue = 7;

    int secondTrueAns = 0;
    int secondFalseAns = 0;

    int thirdTrueAns = 0;
    int thirdFalseAns = 0;
    int thirdFirstValue = 711;
    int thirdSecondValue = 7;

    int fourthTrueAns = 0;
    int fourthFalseAns = 0;
    double fourthFirstValue = 41.735;
    double fourthSecondValue = 23.836;

    int fifthTrueAns = 0;
    int fifthFalseAns = 0;
    double fifthFirstValue = 71159;
    double fifthSecondValue = 14704;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    }


    public void check1st(View v) {
        int firstRealAns ;
        TextView first1st = (TextView) findViewById(R.id.first_1st);
        TextView first2nd = (TextView) findViewById(R.id.first_2nd);
        TextView firstTrueAnsText = (TextView) findViewById(R.id.first_true_ans);
        TextView firstFalseAnsText = (TextView) findViewById(R.id.first_false_ans);
        EditText firstAns = (EditText) findViewById(R.id.first_ans);

        firstRealAns = firstFirstValue * firstSecondValue;


        if (firstAns.getText().toString().equals(String.valueOf(firstRealAns))) {

            firstTrueAns += 1;
            firstTrueAnsText.setText(String.valueOf(firstTrueAns));

        } else {

            firstFalseAns += 1;
            firstFalseAnsText.setText(String.valueOf(firstFalseAns));
            Toast.makeText(this, "Wrong answer, The true answer is " + firstRealAns, Toast.LENGTH_LONG).show();
        }

        Random rand = new Random();
        firstFirstValue = rand.nextInt(13) + 1;
        firstSecondValue = rand.nextInt(13) + 1;
        first1st.setText(String.valueOf(firstFirstValue));
        first2nd.setText(String.valueOf(firstSecondValue));
        firstAns.setText("");
    }

    public void check2nd() {

    }


    public void check3rd(View v) {
        int thirdRealAns = 0;
        TextView third1st = (TextView) findViewById(R.id.third_1st);
        TextView third2nd = (TextView) findViewById(R.id.third_2nd);
        EditText thirdAns = (EditText) findViewById(R.id.third_ans);
        TextView thirdTrueAnsText = (TextView) findViewById(R.id.third_true_ans);
        TextView thirdFalseAnsText = (TextView) findViewById(R.id.third_false_ans);


        thirdRealAns = thirdFirstValue * thirdSecondValue;


        String ans = thirdAns.getText().toString();
        if (ans.equals(String.valueOf(thirdRealAns))) {

            thirdTrueAns += 1;
            thirdTrueAnsText.setText(String.valueOf(thirdTrueAns));

        } else {

            thirdFalseAns += 1;
            thirdFalseAnsText.setText(String.valueOf(thirdFalseAns));
            Toast.makeText(this, "Wrong answer, The true answer is " + thirdRealAns, Toast.LENGTH_LONG).show();
        }

        Random rand = new Random();
        thirdFirstValue = rand.nextInt(10) + 1;
        thirdSecondValue = rand.nextInt(1000) + 1;
        third1st.setText(String.valueOf(thirdFirstValue));
        third2nd.setText(String.valueOf(thirdSecondValue));
        thirdAns.setText("");
    }

    public void check4th(View v) {
        double fourthRealAns ;
        TextView fourth1st = (TextView) findViewById(R.id.fourth_1st);
        TextView fourth2nd = (TextView) findViewById(R.id.fourth_2nd);
        TextView fourthTrueAnsText = (TextView) findViewById(R.id.fourth_true_ans);
        TextView fourthFalseAnsText = (TextView) findViewById(R.id.fourth_false_ans);
        EditText fourthAns = (EditText) findViewById(R.id.fourth_ans);

        fourthRealAns = (fourthFirstValue + fourthSecondValue) / 1000;


        if (fourthAns.getText().toString().equals(String.valueOf(fourthRealAns))) {

            fourthTrueAns += 1;
            fourthTrueAnsText.setText(String.valueOf(fourthTrueAns));

        } else {

            fourthFalseAns += 1;
            fourthFalseAnsText.setText(String.valueOf(fourthFalseAns));
            Toast.makeText(this, "Wrong answer, The true answer is " + fourthRealAns, Toast.LENGTH_LONG).show();
        }

        Random rand = new Random();
        fourthFirstValue = (rand.nextInt(100000) + 1) / 1000;
        fourthSecondValue = (rand.nextInt(100000) + 1) /1000;
        fourth1st.setText(String.valueOf(firstFirstValue));
        fourth2nd.setText(String.valueOf(firstSecondValue));
        fourthAns.setText("");
    }

    public void check5th(View v) {
        double fifthRealAns ;
        TextView fifth1st = (TextView) findViewById(R.id.fifth_1st);
        TextView fifth2nd = (TextView) findViewById(R.id.fifth_2nd);
        TextView fifthTrueAnsText = (TextView) findViewById(R.id.fifth_true_ans);
        TextView fifthFalseAnsText = (TextView) findViewById(R.id.fifth_false_ans);
        EditText fifthAns = (EditText) findViewById(R.id.fifth_ans);

        fifthRealAns = fifthFirstValue - fifthSecondValue;


        if (fifthAns.getText().toString().equals(String.valueOf(fifthRealAns))) {

            fifthTrueAns += 1;
            fifthTrueAnsText.setText(String.valueOf(fifthTrueAns));

        } else {

            firstFalseAns += 1;
            fifthFalseAnsText.setText(String.valueOf(fifthFalseAns));
            Toast.makeText(this, "Wrong answer, The true answer is " + fifthRealAns, Toast.LENGTH_LONG).show();
        }

        Random rand = new Random();
        fifthFirstValue = rand.nextInt(100000) + 1;
        fifthSecondValue = rand.nextInt((int) fifthSecondValue) + 1;
        fifth1st.setText(String.valueOf(fifthFirstValue / 1000));
        fifth2nd.setText(String.valueOf(fifthSecondValue / 1000));
        fifthAns.setText("");
    }
}

Answer 1

你应该在（;）之前的值之后添加一个（d），如下例所示：

fourthFirstValue = 41.735d ;

当我声明一个double并赋值时，它返回一个整数值

1 个答案: