Java 语法错误setOnClickListener

我正在翻阅一本java练习册，并被这个语法错误所困扰。我搜索了onSetClickListener语法错误，不认为我在重复问题。Eclipse显示“标记“setOnClickListener”上的语法错误，该标记后面应该是标识符”。谢谢你的帮助

package fifth.example.eventhandling;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity implements OnClickListener{
    Button button = (Button)findViewById(R.id.button1);
    button.setOnClickListener(this);  <<ERROR HERE

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    @Override
    public void onClick(View arg0) {
        TextView text = (TextView)findViewById(R.id.textmessage);
        text.setText("BUTTON HAS BEEN CLICKED. EVENT PROCESSED.");

    }

}

package fifth.example.eventhandling；
导入android.os.Bundle；
导入android.app.Activity；
导入android.view.Menu；
导入android.view.view；
导入android.view.view.OnClickListener；
导入android.widget.Button；
导入android.widget.TextView；
公共类MainActivity扩展活动实现OnClickListener{
按钮按钮=（按钮）findViewById（R.id.button1）；
setOnClickListener（this）；一个问题是：代码中与按钮相关的代码应该在
onCreate（）内部和
setContentView之后…

    Button button = (Button)findViewById(R.id.button1);
    button.setOnClickListener(this);  <<ERROR HERE

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

Button-Button=（Button）findViewById（R.id.button1）；
button.setOnClickListener（this）；当前，您正在尝试在设置活动布局之前初始化按钮。将按钮初始化移动到
setContentView
之后的onCreate of Activity中，如下所示：

public class MainActivity extends Activity implements OnClickListener{
    Button button ; //<<< declare  button here

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

       button = (Button)findViewById(R.id.button1);  //<<< initilze here
       button.setOnClickListener(this);   
    }

public类MainActivity扩展活动实现OnClickListener{
按钮按钮；//您的代码应该是这样的

public class MainActivity extends Activity implements OnClickListener{


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

Button button = (Button)findViewById(R.id.button1);
button.setOnClickListener(this);  <<ERROR HERE
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

@Override
public void onClick(View arg0) {
    TextView text = (TextView)findViewById(R.id.textmessage);
    text.setText("BUTTON HAS BEEN CLICKED. EVENT PROCESSED.");

}

public类MainActivity扩展活动实现OnClickListener{
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
按钮按钮=（按钮）findViewById（R.id.button1）；
button.setOnClickListener（这个）；@viatierra：这不是在得到答案后问问题的正确方式删除它。如果你在这里得到帮助，请接受答案
public class MainActivity extends Activity implements OnClickListener{


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

Button button = (Button)findViewById(R.id.button1);
button.setOnClickListener(this);  <<ERROR HERE
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}

@Override
public void onClick(View arg0) {
    TextView text = (TextView)findViewById(R.id.textmessage);
    text.setText("BUTTON HAS BEEN CLICKED. EVENT PROCESSED.");

}