Java 找不到符号'；上下文'；，android.content.Context

我有以下代码：

package com.androidtest.notification;

import android.app.Activity;
import android.os.Bundle;
import android.widget;
import android.widget.Toast;
import android.content.Context;

public class activityNotification extends Activity
{

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Context context = getApplicationContext();
        CharSequence text = "Hello toast!";
        int duration = Toast.LENGTH_SHORT;

        Toast toast = Toast.makeText(context, text, duration);
        toast.show();
    }
}

我试图在命令行“$ant build”上使用ant编译它，但我一直收到以下错误：

error: cannot find symbol
[javac]         Context context = getApplicationContext();
[javac]         ^

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有什么建议吗？谢谢

活动中的上下文是通过您的活动获取的。使用此

package com.androidtest.notification;

import android.app.Activity;
import android.os.Bundle;
import android.widget;
import android.widget.Toast;
import android.content.Context;

public class ActivityNotification extends Activity
{

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Context context = this; // or ActivityNotification.this
        CharSequence text = "Hello toast!";
        int duration = Toast.LENGTH_SHORT;

        Toast toast = Toast.makeText(this, text, duration);
        toast.show();
    }
}

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简短回答：加上这个

import android.content.Context;

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这个呢？Context=getApplicationContext（）；