Activity 的随机 xml 布局文件

Question

我有五个布局（XML 文件），每个布局上都有一个Button 和两个活动，A 和 B。在 A 中启动按钮的 onClick 动作中，我将打开活动 B 和所有故事从这里开始：

在我的活动B中，首先，我想显示这五个xml文件中的一个和onclick中的onclick 在五个XML文件的每一个中，我想随机打开剩余的4个xml文件, 直到按下返回按钮。。有什么办法可以做到这一点，或者我必须有 5 个活动，每个活动都有一个布局？

我的问题是：

只有一个 Xml 文件随机出现在活动 B 上，并且该 xml 文件上的 Button 没有响应，即不显示下一个 xml 文件。

这是我的活动 B 的代码：

public class B extends Activity {
Handler handler = new Handler();
Button bt;

int[] layouts = {R.layout.first,R.layout.second,R.layout.third,R.layout.fourth,R.layout.fifth};
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);


    bt = (Button)findViewById(R.id.button1);

    bt.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub

            handler.postDelayed(new Runnable() {

                @Override
                public void run() {
                    // TODO Auto-generated method stub

                    for (int i = 0; i < layouts.length; i++) {


                        setContentView(layouts[rand]);
                    }

                }
            }, 2000);

        }
    });


}

所有 5 个 Xml 文件都将采用相同的模式：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity" >

<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:gravity="center"
    android:text="@string/hello_world" />

<Button
    android:id="@+id/button5"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:layout_marginTop="10dp"
    android:onClick="showLayouts"
    android:text="5th" />

我是Java新手，所以卡在这里，如果任何简单的线索也能帮助我。我已经搜索了这个论坛并没有找到相关的解决方案。

@LuksProg，Logcat 错误是这样的：

  **03-11 05:51:16.147: E/AndroidRuntime(1575): FATAL EXCEPTION: main
 03-11 05:51:16.147: E/AndroidRuntime(1575): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.SAI.wth/com.SAI.wth.ReceivingActivity}: java.lang.NullPointerException
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at android.app.ActivityThread.access$600(ActivityThread.java:141)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at android.os.Handler.dispatchMessage(Handler.java:99)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at android.os.Looper.loop(Looper.java:137)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at android.app.ActivityThread.main(ActivityThread.java:5039)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at java.lang.reflect.Method.invokeNative(Native Method)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at java.lang.reflect.Method.invoke(Method.java:511)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at dalvik.system.NativeStart.main(Native Method)
 03-11 05:51:16.147: E/AndroidRuntime(1575): Caused by: java.lang.NullPointerException
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at com.SAI.wth.ReceivingActivity.onCreate(ReceivingActivity.java:40)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at android.app.Activity.performCreate(Activity.java:5104)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
 03-11 05:51:16.147: E/AndroidRuntime(1575):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)**

这次我想做这个，

    switch (mPosition) {
                            case R.layout.first:
                                Toast.makeText(getApplicationContext(), "First", Toast.LENGTH_SHORT).show();

                                break;

                            case R.layout.second:
                                Toast.makeText(getApplicationContext(), "second", Toast.LENGTH_SHORT).show();
//Some sound                                
                                break;

                            case R.layout.third:
                                Toast.makeText(getApplicationContext(), "third", Toast.LENGTH_SHORT).show();
    //Some media , Different for each Layout..                          
                                break;  

                            case R.layout.fourth:
                                Toast.makeText(getApplicationContext(), "fourth", Toast.LENGTH_SHORT).show();

                                break;

                            case R.layout.fifth:
                                Toast.makeText(getApplicationContext(), "fifth", Toast.LENGTH_SHORT).show();

                                break;  
                            default:
                                break;
                            }


                            Collections.shuffle(mLayouts);
                        }
                        mPosition = 0;
                    }   

Answer 1

只有一个 Xml 文件随机出现在活动 B 和按钮上 该 xml 文件没有响应，即没有显示下一个 xml 文件。

你会想要这样的东西：

private int mPosition = 0;
private Handler mHandler = new Handler();
private List<Integer> mLayouts;
private Button mButton;

private OnClickListener mListener = new OnClickListener() {

    @Override
    public void onClick(View v) {
        mHandler.postDelayed(new Runnable() {

            @Override
            public void run() {
                // as you're posting this delayed you may want to make sure the 
                // user doesn't click this Buton again in the two seconds interval
                if (mPosition >= mLayouts.size()) { // revert the list
                    int lastId = mLayouts.get(mLayouts.size() - 1);
                    Collections.shuffle(mLayouts);
                    // do this so if we randomize the layouts we don't end
                    // up after the shuffle with the same layout on the
                    // first
                    // position as the last position
                    while (lastId == mLayouts.get(0)) {
                        Collections.shuffle(mLayouts);
                    }
                    mPosition = 0;
                }
                setContentView(mLayouts.get(mPosition));
                mPosition++;
                mButton = (Button) findViewById(R.id.btnId);
                mButton.setOnClickListener(mListener);
            }

        }, 2000);           
    }

};

在onCreate 方法中：

    mLayouts = new ArrayList<Integer>();
    mLayouts.add(R.layout.layout1);
    mLayouts.add(R.layout.layout2);
    mLayouts.add(R.layout.layout3);
    mLayouts.add(R.layout.layout4);
    mLayouts.add(R.layout.layout5);
    Collections.shuffle(mLayouts);
    setContentView(mLayouts.get(mPosition));
    mButton = (Button) findViewById(R.id.btnId);
    mButton.setOnClickListener(mListener);
    mPosition++;

Answer 2

当我这样做时似乎工作得很好：

public class MainActivity extends Activity implements OnClickListener {
    Handler handler = new Handler();
    Button bt;

    int[] layouts = { R.layout.first, R.layout.second, R.layout.third, R.layout.fourth,
        R.layout.fifth };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.first);

        bt = (Button) findViewById(R.id.button5);

        bt.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {
        if(v.getId() == R.id.button5){

            handler.postDelayed(new Runnable() {

                @Override
                    public void run() {
                    // TODO Auto-generated method stub
                    int rand = (int) Math.floor(Math.random() * layouts.length);
                    setContentView(layouts[rand]);


                    bt = (Button) findViewById(R.id.button5);
                    bt.setOnClickListener(MainActivity.this);

                }
            }, 2000);

        }

    }
}