如何为导航和当前活动设置 On back 选项答案

【问题标题】：How to set On back option for Navigation and Current activity如何为导航和当前活动设置 On back 选项
【发布时间】：2020-05-04 12:23:31
【问题描述】：

我创建了一个带有列表视图的应用程序，当我从主页单击返回按钮时，它会显示一条消息并要求退出或不退出。在我实现了导航抽屉并设置打开和关闭之后。但是当我从导航中单击返回按钮时，返回并弹出我设置为锄头页面的吐司。

@Override
public void onBackPressed() {

    if (drawerLayout.isDrawerOpen(GravityCompat.START)){
        drawerLayout.closeDrawer(GravityCompat.START);
    }else{
        super.onBackPressed();
    }

    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("Are you sure you want to Exit?")
            .setCancelable(false)
            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    finish();
                    AdminHome.super.onBackPressed();
                }
            })

            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                }
            });

    AlertDialog alertDialog = builder.create();
    alertDialog.show();
}

当我从导航栏点击返回并从主页设置 toast 时，如何停止 toast 消息。

【问题讨论】：

标签： java android android-layout button navigation

【解决方案1】：

您好，您可以像这样更改您的代码

@Override
public void onBackPressed() {

if (drawerLayout.isDrawerOpen(GravityCompat.START)){
    drawerLayout.closeDrawer(GravityCompat.START);
}else{
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Are you sure you want to Exit?")
        .setCancelable(false)
        .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                finish();
                AdminHome.super.onBackPressed();
            }
        })

        .setNegativeButton("No", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.cancel();
            }
        });

AlertDialog alertDialog = builder.create();
alertDialog.show();
}

}

【讨论】：

【解决方案2】：

将 AlertDialog 代码放在 else 块中。

【讨论】：

【解决方案3】：

将您的警报对话框放入您的状况的else

@Override
public void onBackPressed() {

    if (drawerLayout.isDrawerOpen(GravityCompat.START)){
        drawerLayout.closeDrawer(GravityCompat.START);
    }else{
            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.setMessage("Are you sure you want to Exit?")
            .setCancelable(false)
            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    super.onBackPressed();
                }
            })

            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                }
            });

           AlertDialog alertDialog = builder.create();
           alertDialog.show();
    }

}

【讨论】：