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Android 无法访问另一个活动中一个活动的变量_Android_Variables_Android Activity - Fatal编程技术网

Android 无法访问另一个活动中一个活动的变量

Android 无法访问另一个活动中一个活动的变量,android,variables,android-activity,Android,Variables,Android Activity,我的第一个活动包括以下代码 mHandler.postDelayed(mLaunchTask,10000); private Runnable mLaunchTask = new Runnable() { public void run() { Intent i = new Intent(getApplicationContext(),NearestPoint.cl

我的第一个活动包括以下代码

mHandler.postDelayed(mLaunchTask,10000);
private Runnable mLaunchTask = new Runnable() 
            {
                public void run() 
                {
                    Intent i = new Intent(getApplicationContext(),NearestPoint.class);
                    Bundle params = new Bundle();
                    params.putFloat("latiA", latA);
                    params.putFloat("longiA", longA);
                    params.putFloat("latiB", latB);
                    params.putFloat("longiB", longB);
                    params.putFloat("latiC", latC);
                    params.putFloat("longiC", longC);
                    i.putExtras(params);
                    startActivity(i);
                }
            };    
最近点的活动包括此代码

public float latA, longA, latB, longB, latC, longC;
  Intent it = getIntent(); {        
   if (it != null)
   {
       Bundle params = it.getExtras();
       if (params != null)
       {
            latA = params.getFloat("latiA");
            longA = params.getFloat("longiA");  
            latB = params.getFloat("latiB");
            longB = params.getFloat("longiB");  
            latC = params.getFloat("latiC");
            longC = params.getFloat("longiC");  
        }
   }}
我无法在最近点活动中正确访问latA、longA等值。 我尝试使用Toast显示:

Toast.makeText(getApplicationContext(),"\nPoint A: \nLatitude: " + latA  + "\nLongitude: " + longA,  Toast.LENGTH_LONG).show(); 
在FirstActivity中,它给出了正确的值,但在最近的点上,我得到的纬度和经度都是0.0

这是我的舱单:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.gpsdistance"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="16" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.gpsdistance.FirstActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name="com.example.gpsdistance.NearestPoint"
            android:label="@string/title_activity_nearest_point" >
        </activity>
        <activity
            android:name="com.example.gpsdistance.MinimumDistance"
            android:label="@string/title_activity_minimum_distance" >
        </activity>
    </application>

    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.INTERNET" />

</manifest>


请提供帮助。

发生这种情况是因为在实例化可运行时,latA、longA、latB、longB、latC、longC的值为零。您应该为每个值使用一个getter,如下所示:

mHandler.postDelayed(mLaunchTask,10000);
private Runnable mLaunchTask = new Runnable() 
            {
                public void run() 
                {
                    Intent i = new Intent(getApplicationContext(),NearestPoint.class);
                    Bundle params = new Bundle();
                    params.putFloat("latiA", getLatiA()); //You should to call a getter here
                    i.putExtras(params);
                    startActivity(i);
                }
            };    



//In your class     
private double getLatiA() {
  return this.latiA;
}

我不明白你为什么在另一个线程中运行活动。我建议使用服务

我可以看看你的清单文件吗。因为我刚刚尝试了这个示例,它对我来说运行良好。我添加了清单文件。我还添加了FirstActivity类中的完整代码。进行测试。在runnable中放入一个硬代码值,以查看该值是否已发送。如参数putFloat(“latiA”,21.4);您最近的点试图从intent获取额外值的方法是什么?方法是points()。它在班级活动中。我已经添加了完整项目的链接。一定要看一看。我尝试通过构造函数获取值,但即使这样也不起作用。
mHandler.postDelayed(mLaunchTask,10000);
private Runnable mLaunchTask = new Runnable() 
            {
                public void run() 
                {
                    Intent i = new Intent(getApplicationContext(),NearestPoint.class);
                    Bundle params = new Bundle();
                    params.putFloat("latiA", getLatiA()); //You should to call a getter here
                    i.putExtras(params);
                    startActivity(i);
                }
            };    



//In your class     
private double getLatiA() {
  return this.latiA;
}