Question

我创建了一个titile_layout.xml，我想将TitleLayout用于Mainactivity。但是当我按下按钮时创建AlertDialog时，会出现如下错误。我想也许是＃34; TitleLayout.this＆＃34;？但如果我不使用它，我该怎么用？为什么呢？

package cn.example.uilayouttest;

import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.content.Context;
import android.content.DialogInterface;
import android.support.v4.widget.SimpleCursorAdapter.ViewBinder;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

public class TitleLayout extends LinearLayout  {

    public TitleLayout(Context context, AttributeSet attrs) {
        super(context, attrs);

        LayoutInflater.from(context).inflate(R.layout.title_layout, TitleLayout.this);

        Button btn1 = (Button) findViewById(R.id.button1);
        Button btn2 = (Button) findViewById(R.id.button2);
        TextView tv = (TextView) findViewById(R.id.text_view);

        btn1.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // The wrong is here:The constructor AlertDialog.Builder(TitleLayout) is undefined
                AlertDialog.Builder ad = new AlertDialog.Builder(TitleLayout.this);
                ad.setTitle("fefsfs");
                ad.setMessage("fefwefw");
                ad.setPositiveButton("fefw", new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        // TODO Auto-generated method stub

                    }
                });
                ad.show();
            }
        });
        btn2.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

            }
        });


    }
//  public void onclick ()

}

Answer 1

第一个参数是Context对象。变化

new AlertDialog.Builder(TitleLayout.this);

与

new AlertDialog.Builder(getContext());

或将构造函数的Context对象标记为final并使用它

 public TitleLayout(final Context context, AttributeSet attrs) 

 /// other code

 new AlertDialog.Builder(context);

Answer 2

Your Activity exetends LinearLayout，因此它不提供任何上下文，context实际上与您当前的网页相关，例如this关键字。

只需使用

AlertDialog.Builder ad = new AlertDialog.Builder(context);

构造函数AlertDialog.Builder（TitleLayout）未定义

2 个答案: