android - 对话框

目标

• 了解常用对话框的类型
• 掌握对话框的一般实现
• 掌握单选（多选）按钮对话框获取选项的方法
• 学会使用对话框来确认程序的退出。

一、消息提示对话框

1. 创建AlertDialog.Builder对象
2. 设置图标、标题、内容、按钮等区域
3. 调用create()方法创建
4. 调用show()方法显示对话框

 @Override
    public boolean onItemLongClick(AdapterView adapterView, View view, int position, long l) {
        //Toast.makeText(this, "长按"+position,  Toast.LENGTH_SHORT).show();

        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setIcon(R.drawable.laker);
        builder.setTitle("消息提示");
        builder.setMessage("这是一个简单的消息提示");
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener(){
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                Toast.makeText(MainActivity.this, "点击了确定", Toast.LENGTH_SHORT).show();
            }
        });
        builder.create().show();
        return true;
    }

二、确认对话框

• 不调用setMessage()方法设置内容
• 调用setNegativeButton()方法添加取消按钮

@Override
    public boolean onItemLongClick(AdapterView adapterView, View view, int position, long l) {
        //Toast.makeText(this, "长按"+position,  Toast.LENGTH_SHORT).show();

        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setIcon(R.drawable.laker);
        builder.setTitle("消息提示");
//        builder.setMessage("这是一个简单的消息提示");
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener(){
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
               finish();
            }
        });
        builder.setNegativeButton("取消", null);
        builder.create().show();
        return true;
    }

三、列表对话框

 @Override
    public boolean onItemLongClick(AdapterView adapterView, View view, int position, long l) {
        //Toast.makeText(this, "长按"+position,  Toast.LENGTH_SHORT).show();

        final String[] arr = {"初始android", "开发环境搭建", "基础控件", "UI控件"};
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setIcon(R.drawable.laker);
        builder.setTitle("消息提示");
        builder.setItems(arr, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                Toast.makeText(MainActivity.this, arr[i], Toast.LENGTH_SHORT).show();
            }
        });
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener(){
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
               finish();
            }
        });
        builder.create().show();
        return true;
    }

四、单选对话框

• 准备一个数组资源
• 调用setSingleChoiceItems()设置单选列表项

 int selected = 0;
    @Override
    public boolean onItemLongClick(AdapterView adapterView, View view, int position, long l) {
        //Toast.makeText(this, "长按"+position,  Toast.LENGTH_SHORT).show();

        final String[] arr = {"熊猫", "大象", "长颈鹿", "蜘蛛侠"};
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setIcon(R.drawable.rockets);
        builder.setTitle("消息提示");
        builder.setSingleChoiceItems(arr, 0, new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                selected = i;
                Toast.makeText(MainActivity.this, "用户选择了"+arr[selected], Toast.LENGTH_SHORT).show();
                dialogInterface.dismiss();
            }
        }); // 0表示默认第一个选项
        builder.setPositiveButton("确定", new DialogInterface.OnClickListener(){
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
               finish();
            }
        });
        builder.create().show();
        return true;
    }

五、多选对话框

• 准备一个数组资源
• 调用setMultiChoiceItems()设置多选列表项

六、实现程序退出确认框

• 重写onBackPress方法
• 去除原有的父类方法
• 编写确认对话框
• 在确定事件中国调用finish来结束程序

 // 退出
    @Override
    public void onBackPressed() {
        new AlertDialog.Builder(this)
                .setIcon(R.drawable.rockets)
                .setTitle("确认对话框")
                .setMessage("确定要退出程序？")
                .setNegativeButton("取消", null)
                .setPositiveButton("残忍离开", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        finish();

                // System.exit(0);

                    }
                }).show();
    }