android - 何时将此或上下文与警报对话框一起使用

Question

我正在尝试创建一个警告对话框，但在声明的括号中，在它说的那一行:

AlertDialog.Builder alertDialog=new AlertDialog.Builder(this).create();

(this) 导致错误。我尝试将其更改为上下文，但还有更多错误。帮助？

import android.app.Activity;
import android.app.AlertDialog.Builder;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.app.AlertDialog;

public class userPreferences extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.userpreferences);
    EditText editText=(EditText)findViewById(R.id.editText);
    Button save=(Button)findViewById(R.id.button);


  save.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
          AlertDialog.Builder alertDialog=new AlertDialog.Builder(this).create();
                  alertDialog.setTitle("Alert Dialog");
                  alertDialog.setMessage("Are you sure you want to save?");
                  alertDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                      @Override
                      public void onClick(DialogInterface dialog, int which) {

                      }
                  });
                  alertDialog.setNegativeButton("No", null);
                  alertDialog.show();


      }
  });

}
}

Answer 1

alertDialog 应声明为 final outside OnClickListener:

final AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);

save.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {

        alertDialog.setTitle("Alert Dialog");
        alertDialog.setMessage("Are you sure you want to save?");
        alertDialog.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                ...
            }
        });
        alertDialog.setNegativeButton("No", null);
        alertDialog.show();
    }
});

希望这对您有所帮助。