如何动态添加进度条到布局

Question

我正在掷骰子并使用随机函数我正在计算数字。 1s，2s，3s，4s，5s，6s打印出来。如果它需要太多时间，那么它将显示进度条。为什么我的android代码没有显示进度条虽然我在我的java代码中使用了进度条？ Plz弄清楚错误。

Java代码

package dead.asynctaskprogressbar;

import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.TextView;

import java.util.Random;

public class MainActivity extends AppCompatActivity {

    EditText editText;
    TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView=(TextView)findViewById(R.id.textView);
        editText=(EditText)findViewById(R.id.editText);

    }
    public class Asynctask extends AsyncTask<Integer,Integer,String>{
        ProgressBar bar;
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            bar=new ProgressBar(MainActivity.this,null,android.R.attr.progressBarStyleHorizontal);

            bar.setVisibility(View.VISIBLE);

            bar.setMax(Integer.parseInt(editText.getText().toString().trim()));

        }

        @Override
        protected String doInBackground(Integer... integers) {
            Random random=new Random();
            int ones=0,twos=0,threes=0,fours=0,fives=0,sixes=0,a;

            double currentProgress=0;
            double previousprogress=0;

            for (int i=0;i<integers[0];i++){
                currentProgress=(double)i/integers[0];

                if (currentProgress-previousprogress>=0.02){
                    previousprogress=currentProgress;
                    publishProgress(i);
                }

                 a=  random.nextInt(6)+1;
                switch (a){
                    case 1:
                        ones++;
                        break;
                    case 2:
                        twos++;
                        break;
                    case 3:
                        threes++;
                        break;
                    case 4:
                        fours++;
                        break;
                    case 5:
                        fives++;
                        break;
                    default:
                        sixes++;

                }
            }
            String results="Ones :"+ones +"\n"+"Twos :"+twos +"\n"+"Threes :"+threes +"\n"+"Fours :"+fours +"\n"+"Fives :"+fives +"\n"+"Sixes :"+sixes +"\n";


            return results;
        }

        @Override
        protected void onProgressUpdate(Integer... values) {

            super.onProgressUpdate(values);
            bar.setProgress(values[0]);
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);

                textView.setText(s);

        }
    }

    public void Dice(View view){

        int not=Integer.parseInt(editText.getText().toString().trim());
        new  Asynctask().execute(not);
    }
}

Xml代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="dead.asynctaskprogressbar.MainActivity">

    <EditText
        android:id="@+id/editText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:gravity="center_horizontal"
        android:hint="Dice"
        android:inputType="textPersonName"
        android:padding="10dp" />

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="Dice"
        android:text="Roll Dice" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="TextView"
        android:textSize="20dp" />
</LinearLayout>

Answer 1

  

为什么我的Android代码没有显示进度条

您已动态创建 ProgressBar ，但您未在布局中添加 ProgressBar ，这就是为什么不显示

您需要在布局中添加 ProgressBar

尝试以下代码，它将正常工作

示例代码

public class MainActivity extends AppCompatActivity {


    ProgressBar bar;
    LinearLayout rootView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bar=new ProgressBar(MainActivity.this,null,android.R.attr.progressBarStyleHorizontal);
        rootView=findViewById(R.id.rootView);
        rootView.addView(bar);
        bar.setVisibility(View.GONE);

    }

    public class Asynctask extends AsyncTask<Integer,Integer,String>{

        @Override
        protected void onPreExecute() {
            super.onPreExecute();


            bar.setVisibility(View.VISIBLE);

            bar.setMax(Integer.parseInt(editText.getText().toString().trim()));

        }

        @Override
        protected String doInBackground(Integer... integers) {
            Random random=new Random();
            int ones=0,twos=0,threes=0,fours=0,fives=0,sixes=0,a;

            double currentProgress=0;
            double previousprogress=0;

            for (int i=0;i<integers[0];i++){
                currentProgress=(double)i/integers[0];

                if (currentProgress-previousprogress>=0.02){
                    previousprogress=currentProgress;
                    publishProgress(i);
                }

                a=  random.nextInt(6)+1;
                switch (a){
                    case 1:
                        ones++;
                        break;
                    case 2:
                        twos++;
                        break;
                    case 3:
                        threes++;
                        break;
                    case 4:
                        fours++;
                        break;
                    case 5:
                        fives++;
                        break;
                    default:
                        sixes++;

                }
            }
            String results="Ones :"+ones +"\n"+"Twos :"+twos +"\n"+"Threes :"+threes +"\n"+"Fours :"+fours +"\n"+"Fives :"+fives +"\n"+"Sixes :"+sixes +"\n";


            return results;
        }

        @Override
        protected void onProgressUpdate(Integer... values) {

            super.onProgressUpdate(values);
            bar.setProgress(values[0]);
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);

            textView.setText(s);

        }
    }

    public void Dice(View view){

        int not=Integer.parseInt(editText.getText().toString().trim());
        new  Asynctask().execute(not);
    }
}