android - 使用线程显示进度条

Question

我正在尝试使用线程来显示进度条。我承认我对线程没有那么多的概念。

这是代码

public class Progress extends Activity {

    static String[] display;
    private static final int Progress = 0;      
    private ProgressBar mProgress;
    private int mProgressStatus = 0;
    private Handler mHandler = new Handler();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.progress);

        mProgress = (ProgressBar) findViewById(R.id.progressBar);

        // Start lengthy operation in a background thread
        new Thread(new Runnable() {
            public void run() {
                while (mProgressStatus < 100) {
                    mProgressStatus = doWork();

                    // Update the progress bar
                    mHandler.post(new Runnable() {
                        public void run() {
                            mProgress.setProgress(mProgressStatus);
                        }
                    });
                }
            }

            private int doWork() {                  
                display = new Logic().finaldata();
                // TODO Auto-generated method stub
                return 100;
            }
        }).start();
    }
}

在运行时，logcat 消息是

java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()

我在这里做错了什么？

Answer 1

所以你的问题会在别处。我用 Handler 试过你的例子，它对我有用。

package com.sajmon.threadsDemo;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.ProgressBar;
import android.widget.TextView;

    public class ThreadsDemoActivity extends Activity {

        ProgressBar bar;
        TextView label;
        Handler handler = new Handler();

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
            bar = (ProgressBar) findViewById(R.id.progBar);

            new Thread(new Runnable() {

                int i = 0;
                int progressStatus = 0;

                public void run() {
                    while (progressStatus < 100) {
                        progressStatus += doWork();
                        try {
                            Thread.sleep(500);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }

                        // Update the progress bar
                        handler.post(new Runnable() {
                            public void run() {
                                bar.setProgress(progressStatus);
                                i++;
                            }
                        });
                    }
                }
                private int doWork() {

                    return i * 3;
                 }

                }).start();         

        }
    }

和 XML:

<ProgressBar 
        android:id="@+id/progBar" style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        />

所以看看这个并用类似的方式编辑你的代码。