Android:点击按钮后应用程序崩溃

Android: app crashing after button click

我是 android 的新手,我正在使用 Android Studio 2.2 进行编码,我正在尝试构建我的第一个应用程序,基本上该应用程序现在做的不多,然后在为我的应用程序的 onClick 方法添加价格方法后,每当我单击按钮时应用程序都会崩溃。

下面我提供了错误信息和我自己的代码。

我从 android 工作室收到的错误消息与从 logcat 视图复制而来:

10-06 09:46:00.338 30789-30789/com.example.abdulkarim.justjava E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.abdulkarim.justjava, PID: 30789
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:4660)
at android.view.View$PerformClick.run(View.java:19445)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:146)
at android.app.ActivityThread.main(ActivityThread.java:5603)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
at dalvik.system.NativeStart.main(Native Method)

 Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:4660) 
at android.view.View$PerformClick.run(View.java:19445) 
at android.os.Handler.handleCallback(Handler.java:733) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:146) 
at android.app.ActivityThread.main(ActivityThread.java:5603) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) 
at dalvik.system.NativeStart.main(Native Method) 

 Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x2
at android.content.res.Resources.getText(Resources.java:1431)
at android.support.v7.widget.ResourcesWrapper.getText(ResourcesWrapper.java:52)
at android.widget.TextView.setText(TextView.java:4954)
at com.example.abdulkarim.justjava.MainActivity.display(MainActivity.java:33)
at com.example.abdulkarim.justjava.MainActivity.submit(MainActivity.java:24)
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
at android.view.View.performClick(View.java:4660) 
at android.view.View$PerformClick.run(View.java:19445) 
at android.os.Handler.handleCallback(Handler.java:733) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:146) 
at android.app.ActivityThread.main(ActivityThread.java:5603) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099) 
at dalvik.system.NativeStart.main(Native Method) 
10-06 09:47:13.823 30789-30789/? I/Process: Sending signal. PID: 30789 SIG: 9

这是我的 MainActivity.java 代码

package com.example.abdulkarim.justjava;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

import java.text.NumberFormat;


public class MainActivity extends AppCompatActivity {

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

    /**
     * This method is called when the order button is clicked.
     */
    public void submit(View view){
        int numberOfCoffees = 2;
        display(numberOfCoffees);
        displayPrice(numberOfCoffees * 10);
    }

    /**
     * This method displays the given quantity on the screen
     */
    private void display(int number){
        TextView quantityTextView = (TextView) findViewById(R.id.quantity_text_view);
        quantityTextView.setText(number);
    }

    /**
     * This method displays the given price on the screen
     */
    private void displayPrice(int number){
        TextView priceTextView = (TextView) findViewById(R.id.price_text_view);
        priceTextView.setText(NumberFormat.getCurrencyInstance().format(number));
    }
}

这是我来自 main_activity.xml

的布局代码
    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    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"
    android:orientation="vertical"
    tools:context="com.example.abdulkarim.justjava.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Quantity"
        android:textAllCaps="true"
        android:textSize="16sp"
        android:textColor="@android:color/darker_gray"
        android:layout_marginBottom="16dp"/>
    <TextView
        android:id="@+id/quantity_text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="0"
        android:textSize="16sp"
        android:textColor="@android:color/black"
        android:layout_marginBottom="16dp"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Price"
        android:textAllCaps="true"
        android:textSize="16sp"
        android:textColor="@android:color/darker_gray"
        android:layout_marginBottom="16dp"/>
    <TextView
        android:id="@+id/price_text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="[=13=]"
        android:textSize="16sp"
        android:textColor="@android:color/black"
        android:layout_marginBottom="16dp"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Order"
        android:textAllCaps="true"
        android:textSize="16sp"
        android:onClick="submit"/>
</LinearLayout>

请帮我找出代码中的错误。

你不能直接给你的Textview设置整数。只允许使用字符串,因此请更新您的方法,它将起作用:

 /**
     * This method displays the given quantity on the screen
     */
    private void display(int number){
        TextView quantityTextView = (TextView) findViewById(R.id.quantity_text_view);
        quantityTextView.setText(number+"");
    }

    /**
     * This method displays the given price on the screen
     */
    private void displayPrice(int number){
        TextView priceTextView = (TextView) findViewById(R.id.price_text_view);
        priceTextView.setText(NumberFormat.getCurrencyInstance().format(number)+"");
    }

问题出在 Display 函数的下一行,因为您不能通过调用 setText 方法将整数设置为 TextView,而是作为字符串。

quantityTextView.setText(number);

请将此行更改为

quantityTextView.setText(number+"");

你的问题只在

 private void display(int number){
    TextView quantityTextView = (TextView)                                                                             findViewById(R.id.quantity_text_view);
    quantityTextView.setText(number);
}

这里不能直接设置数字。 Hare 仅字符串除外。 您可以添加带有数字的空字符串来解决这个问题...

quantityTextView.setText(number+"");

NumberFormat.getCurrencyInstance().format(number)

return 字符串所以不需要添加任何东西...

settext() 方法接受字符串作为参数。您不能直接将任何其他数据类型传递给它。要在文本视图中显示任何其他数据类型,您必须使用“+”运算符将其附加到字符串:

赞:[textview].setText(""+integerValue);

  1. 这里双引号("")是一个空字符串
  2. and (+) 是附加两个值的运算符。
  3. integerValue 可以是 (1,2,3,4....) 之类的任何东西,你想在 textview 中显示它