Android新手入门教程（六）：理解Activityの显示“进度条”对话框

当要进行耗时的操作的时候，往往会看见“请稍候”字样的对话框。例如，用户正在登入服务器，此时并不允许用户使用这个软件，或者应用程序把结果返回给用户之前，要进行某些耗时的计算。在这些情况下，显示一个“进度条”对话框，能友好地让用户等待，同时也能阻止用户进行某些不必要的操作。

1.创建一个名为Dialog的工程。

2.main.xml中的代码。

[java] <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/btn_dialog2"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="onClick2"
        android:text="Click to display a progress dialog" />

</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

</LinearLayout> 3.DialogActivity.java中的代码。

[java] package net.horsttnann.Dialog;

import net.horsttnann.Dialog.R;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.view.View;

public class DialogActivity extends Activity {
    ProgressDialog progressDialog;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    public void onClick2(View v) {
        // ---show the dialog---
        final ProgressDialog dialog = ProgressDialog.show(this,
                "Doing something", "Please wait...", true);
        new Thread(new Runnable() {
            public void run() {
                try {
                    // ---simulate doing something lengthy---
                    Thread.sleep(5000);
                    // ---dismiss the dialog---
                    dialog.dismiss();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
}
package net.horsttnann.Dialog;

import net.horsttnann.Dialog.R;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.view.View;

public class DialogActivity extends Activity {
ProgressDialog progressDialog;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    public void onClick2(View v) {
        // ---show the dialog---
        final ProgressDialog dialog = ProgressDialog.show(this,
                "Doing something", "Please wait...", true);
        new Thread(new Runnable() {
            public void run() {
                try {
                    // ---simulate doing something lengthy---
                    Thread.sleep(5000);
                    // ---dismiss the dialog---
                    dialog.dismiss();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
}
    4.按F11调试，点击按钮，弹出“进度条”对话框。

效果图：

提示：

补充：移动开发 , Android ,