Question

我在使用此应用程序时遇到了一些问题。一切看起来都不错，但是当我运行应用程序时，它会完美加载，直到我点击计算按钮并尝试让它思考。请给我一个关于修复什么或从哪里开始寻找的提示，因为我很难过！

问题：
1.开始屏幕要求您购买的洗车包装类型。

用户选择哪种类型的洗车 - 仅外部或外部内部真空服务。洗车应用程序收取8.99美元的外部清洗费用和12.99美元的外部清洗，内部真空吸尘器用于12个或更多洗车的包装。如果您选择少于12次洗涤，外部清洗的费用为10.99美元，内部吸尘器的外部费用为15.99美元。
选择CALCULATE PACKAGE按钮后，将显示购买洗车次数的总价格（图4-36）。

收到错误：

 E/AndroidRuntime: FATAL EXCEPTION: main
                      Process: net.androidbootcamp.carwashapp, PID: 3212
                      java.lang.IllegalArgumentException: Cannot format given Object as a Number
                          at java.text.DecimalFormat.format(DecimalFormat.java:593)
                          at java.text.Format.format(Format.java:157)
                          at net.androidbootcamp.carwashapp.MainActivity$1.onClick(MainActivity.java:53)
                          at android.view.View.performClick(View.java:5610)
                          at android.view.View$PerformClick.run(View.java:22265)
                          at android.os.Handler.handleCallback(Handler.java:751)
                          at android.os.Handler.dispatchMessage(Handler.java:95)
                          at android.os.Looper.loop(Looper.java:154)
                          at android.app.ActivityThread.main(ActivityThread.java:6077)
                          at java.lang.reflect.Method.invoke(Native Method)
                          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
                          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

Java代码：

package net.androidbootcamp.carwashapp;

import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.TextView;
import com.google.android.gms.common.api.GoogleApiClient;

import java.text.DecimalFormat;

public class MainActivity extends AppCompatActivity {
    double priceOne = 10.99;
    double discountOne = 8.99;
    double priceTwo = 15.99;
    double discountTwo = 12.99;
    double total;
    double washesEntered;
    /**
     * ATTENTION: This was auto-generated to implement the App Indexing API.
     * See https://g.co/AppIndexing/AndroidStudio for more information.
     */
    private GoogleApiClient client;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
        getSupportActionBar().setLogo(R.mipmap.ic_launcher);
        getSupportActionBar().setDisplayUseLogoEnabled(true);
        final EditText numWashes = (EditText) findViewById(R.id.numOfWashes);
        final RadioButton exteriorOnly = (RadioButton) findViewById(R.id.radExteriorOnly);
        final RadioButton exteriorInterior = (RadioButton) findViewById(R.id.radExteriorInterior);
        final TextView result = (TextView) findViewById(R.id.txtResult);
        Button calc = (Button) findViewById(R.id.btnCalulate);

        calc.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                washesEntered = Double.parseDouble(numWashes.getText().toString());
                DecimalFormat tenth = new DecimalFormat("#.#");
                if (exteriorOnly.isChecked() && washesEntered < 12) {
                    total = washesEntered * priceOne;
                    result.setText(tenth.format("$" + total + " for " + washesEntered + " washes"));
                }
                if (exteriorOnly.isChecked() && washesEntered > 12) {
                    total = washesEntered * discountOne;
                    result.setText(tenth.format("$" + total + " for " + washesEntered + " washes"));
                }
                if (exteriorInterior.isChecked() && washesEntered < 12) {
                    total = washesEntered * priceTwo;
                    result.setText(tenth.format("$" + total + " for " + washesEntered + " washes"));
                }
                if (exteriorInterior.isChecked() && washesEntered > 12) {
                    total = washesEntered * discountTwo;
                    result.setText(tenth.format("$" + total + " for " + washesEntered + " washes"));
                }

            }
        });


    }


}

XML代码：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="net.androidbootcamp.carwashapp.MainActivity">

    <TextView
        android:text="@string/txtDiscount"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/txtDiscount"
        android:textSize="18sp"
        android:layout_below="@+id/txtTitle"
        android:layout_centerHorizontal="true" />

    <Button
        android:text="@string/btnCalculate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btnCalulate"
        android:textSize="24sp"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" />


    <TextView
        android:text="@string/txtTitle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/txtTitle"
        android:textSize="36sp"
        android:textColor="#ffa500"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:srcCompat="@drawable/carwash"
            android:id="@+id/imgCarWash"
            android:contentDescription="@string/imgDescription"
            android:layout_alignParentBottom="true"
            android:layout_alignParentStart="true" />

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/txtResult"
            android:layout_marginTop="46dp"
            android:layout_alignTop="@+id/imgCarWash"
            android:layout_alignEnd="@+id/txtTitle"
            android:textSize="18sp"
            android:textColor="#0000ff"
            android:textAlignment="center" />

    <RadioGroup
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_marginTop="18dp"
        android:layout_below="@+id/txtDiscount"
        android:layout_alignStart="@+id/txtDiscount">

        <RadioButton
            android:text="@string/radExteriorInterior"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/radExteriorOnly"
            android:layout_alignStart="@+id/radExteriorOnly"
            android:layout_marginTop="22dp"
            android:id="@+id/radExteriorInterior" />


        <RadioButton
        android:text="@string/radExteriorOnly"
        android:layout_width="178dp"
        android:layout_height="wrap_content"
        android:id="@+id/radExteriorOnly"
        android:layout_below="@+id/numOfWashes"
        android:layout_toEndOf="@+id/radioGroup4"
        android:layout_marginStart="13dp" />
    </RadioGroup>

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="number"
        android:ems="10"
        android:id="@+id/numOfWashes"
        android:hint="@string/numOfWashes"
        android:layout_below="@+id/txtDiscount"
        android:layout_alignEnd="@+id/txtTitle"
        android:layout_alignStart="@+id/btnCalulate" />

</RelativeLayout>

Answer 1

您对DecimalFormat的使用不正确;你基本上有：

DecimalFormat tenth = new DecimalFormat("#.#");
result.setText(tenth.format("$" + total + " for " + washesEntered + " washes"));

DecimalFormat仅用于格式化单个数字而不是整行输出，如下所示：

result.setText("$" + tenth.format(total) + " for " + washesEntered + " washes"));

应该产生更好的结果。

（另请注意我关于测试washesEntered 12，0.5和-1会发生什么情况的评论。）

Android应用程序代码不起作用

1 个答案: