Variables 无法解析符号变量-扯掉我的头发

我正试图遵循一个教程，并且已经被我认为是完成之前的最后一个错误所困扰

有人能告诉我这些变量有什么问题吗？ 包括以下两项活动，如果任何其他代码适用，我很乐意提供

读取错误代码： 错误：（21，56）错误：找不到符号变量pickupLine 错误：（24，9）错误：找不到符号变量retryButton 错误：任务“：app:compiledBugJavaWithJavaC”的执行失败

编译失败；有关详细信息，请参阅编译器错误输出

MainActivity.java：

package io.wavey.pickuplesson1;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

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

    // Grab clean button so we can do stuff with it!
    Button cleanButton = (Button) findViewById(R.id.cleanButton);
    final Button dirtyButton = (Button) findViewById(R.id.dirtyButton);


    final String pickupLine = "You had me at hello world";

    //This is a Callback.
    cleanButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            sendLine(pickupLine);
        }
    });


}
//Send to activity
private void sendLine(String pickupLine) {
    Intent intent = new Intent(this, LineActivity.class);
    intent.putExtra("Pickup Line", pickupLine);

    startActivity(intent);
}
}

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

    Bundle pickupData = getIntent().getExtras();

    if (pickupData == null) {
        return;
    }
    String receivedPickupLine = pickupData.getString("Pickup Line");
    TextView newLine = (TextView) findViewById(R.id.pickupLine);
    newLine.setText(receivedPickupLine);

    retryButton.setOnClicklistener (new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            finish();
        }
    });


        }
    }

LineActivity.java：

package io.wavey.pickuplesson1;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

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

    // Grab clean button so we can do stuff with it!
    Button cleanButton = (Button) findViewById(R.id.cleanButton);
    final Button dirtyButton = (Button) findViewById(R.id.dirtyButton);


    final String pickupLine = "You had me at hello world";

    //This is a Callback.
    cleanButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            sendLine(pickupLine);
        }
    });


}
//Send to activity
private void sendLine(String pickupLine) {
    Intent intent = new Intent(this, LineActivity.class);
    intent.putExtra("Pickup Line", pickupLine);

    startActivity(intent);
}
}

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

    Bundle pickupData = getIntent().getExtras();

    if (pickupData == null) {
        return;
    }
    String receivedPickupLine = pickupData.getString("Pickup Line");
    TextView newLine = (TextView) findViewById(R.id.pickupLine);
    newLine.setText(receivedPickupLine);

    retryButton.setOnClicklistener (new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            finish();
        }
    });


        }
    }

---

LineActivity.java:

在onCreate（）方法之外声明最终字符串pickupLine=“You have me at hello world”。为响应Mohit干杯。尽管尝试了，但还是将其移动到了公共类MainActivity下，它仍然抛出错误。我想你的思路是对的。你认为我还做错了什么吗？请为我的noobness提供完整的错误跟踪。我试图弄清楚什么是堆栈跟踪，但它们是巨大的100行日志。这就是你要找的吗？

package io.wavey.pickuplesson1;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

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

    // Grab clean button so we can do stuff with it!
    Button cleanButton = (Button) findViewById(R.id.cleanButton);
    final Button dirtyButton = (Button) findViewById(R.id.dirtyButton);


    final String pickupLine = "You had me at hello world";

    //This is a Callback.
    cleanButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            sendLine(pickupLine);
        }
    });


}
//Send to activity
private void sendLine(String pickupLine) {
    Intent intent = new Intent(this, LineActivity.class);
    intent.putExtra("Pickup Line", pickupLine);

    startActivity(intent);
}
}

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

    Bundle pickupData = getIntent().getExtras();

    if (pickupData == null) {
        return;
    }
    String receivedPickupLine = pickupData.getString("Pickup Line");
    TextView newLine = (TextView) findViewById(R.id.pickupLine);
    newLine.setText(receivedPickupLine);

    retryButton.setOnClicklistener (new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            finish();
        }
    });


        }
    }