我正在使用下面的代码，我有一个没有显示的按钮。我认为它与“SetContentView”有关，因为如果我删除其中一个按钮就会出现。我不知道如何解决这个问题以便一切都显示出来？谢谢！
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.wifi.WifiConfiguration;
import android.net.wifi.WifiManager;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class TestActivity extends Activity {
/** Called when the activity is first created.
* @return */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button OffWifi = (Button)findViewById(R.id.offwifi);
OffWifi.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
WifiManager wifiManager = (WifiManager)getBaseContext().getSystemService(Context.WIFI_SERVICE);
wifiManager.setWifiEnabled(false);
}
});
TextView tv = new TextView(this);
TextView status = new TextView(this);
WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
WifiConfiguration wc = new WifiConfiguration();
wc.SSID = "\"Test\""; //IMP! This should be in Quotes!!
wc.hiddenSSID = true;
wc.status = WifiConfiguration.Status.ENABLED;
wc.priority = 10;
wc.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.WPA_PSK);
wc.allowedProtocols.set(WifiConfiguration.Protocol.RSN);
wc.allowedProtocols.set(WifiConfiguration.Protocol.WPA);
wc.allowedAuthAlgorithms.set(WifiConfiguration.AuthAlgorithm.OPEN);
wc.allowedAuthAlgorithms.set(WifiConfiguration.AuthAlgorithm.SHARED);
wc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.CCMP);
wc.allowedPairwiseCiphers.set(WifiConfiguration.PairwiseCipher.TKIP);
wc.preSharedKey = "\"Password\"";
WifiManager wifiManag = (WifiManager) this.getSystemService(WIFI_SERVICE);
boolean res1 = wifiManag.setWifiEnabled(true);
int res = wifi.addNetwork(checkPreviousConfiguration(wc));
Log.d("WifiPreference", "add Network returned " + res );
boolean es = wifi.saveConfiguration();
Log.d("WifiPreference", "saveConfiguration returned " + es );
boolean b = wifi.enableNetwork(res, true);
Log.d("WifiPreference", "enableNetwork returned " + b );
tv.setText("You are now connected! " +
"Version 1.1");
status.setText("The was an error connecting, please try again.");
//@Override
try {
Thread.sleep(5000);
ConnectivityManager connec = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
if (connec != null && (connec.getNetworkInfo(1).getState() == NetworkInfo.State.CONNECTED) ||(connec.getNetworkInfo(0).getState() == NetworkInfo.State.CONNECTED)){
//You are connected, do something online.
setContentView(tv);
}else if (connec.getNetworkInfo(0).getState() == NetworkInfo.State.DISCONNECTED || connec.getNetworkInfo(1).getState() == NetworkInfo.State.DISCONNECTED ) {
//Not connected.
setContentView(status);
}
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public WifiConfiguration checkPreviousConfiguration(WifiConfiguration wc) {
WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
List<WifiConfiguration> configs = wifi.getConfiguredNetworks();
for(WifiConfiguration config : configs) {
if(config.SSID.equals(wc.SSID)) return config;
}
return wc;
}
}
主XML文件
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="@+id/tv"
android:layout_width="246dp"
android:layout_height="wrap_content" />
<Button
android:id="@+id/offwifi"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Turn Wifi Off" />
</LinearLayout>
答案 0 :(得分：1)
您开始活动，将其内容视图设置为至少包含一个按钮的内容。然后您创建TextViews的新实例。然后在OnCreate中，将内容视图设置为其中一个文本视图。如果已连接，则视图将替换为TextView，如果未连接，则视图将替换为TextView。如果您删除了一个额外设置的内容呼叫，您将看到该按钮取决于您是否已连接。
这种行为可能是您想要的，或者您可能想要做的是将TextView添加到布局中，并使用与FindViewById一样的按钮处理方式获取它们的句柄。然后，您可以避开try块中的所有内容，因为textviews已经使用新文本进行了更新。您的代码目前所做的是用文本视图替换整个布局。
答案 1 :(得分：1)
您需要在main.xml布局文件中获取根对象，即
LinearLayout layout = (LinearLayout) findViewById( R.id.linearlayout1 );
然后你可以用
添加到那个布局（它可能没有被命名为linearlayout1）layout.addView ( status );
答案 2 :(得分：1)
setContentView（）不会向显示添加视图，而是替换它们。这就是你的按钮消失的原因。
在XML布局中使用现有的tv而不是创建新的tv，并且只调用一次setContentReview（）。
像这样：
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button OffWifi = (Button)findViewById(R.id.offwifi);
OffWifi.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
WifiManager wifiManager = (WifiManager)getBaseContext().getSystemService(Context.WIFI_SERVICE);
wifiManager.setWifiEnabled(false);
}
});
// remove these lines
// TextView tv = new TextView(this);
// TextView status = new TextView(this);
// add this line
TextView tv= (TextView) findViewById(R.id.tv);
WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
WifiConfiguration wc....
ect.ect.
Log.d("WifiPreference", "enableNetwork returned " + b );
// let's do this later
//tv.setText("You are now connected! " +
// "Version 1.1");
//status.setText("The was an error connecting, please try again.");
//@Override
try {
Thread.sleep(5000);
ConnectivityManager connec = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
if (connec != null && (connec.getNetworkInfo(1).getState() == NetworkInfo.State.CONNECTED) ||(connec.getNetworkInfo(0).getState() == NetworkInfo.State.CONNECTED)){
//You are connected, do something online.
// setting the ContentView replaces everything, so don't do that
//setContentView(tv);
tv.setText("You are now connected! " +
"Version 1.1");
}else if (connec.getNetworkInfo(0).getState() == NetworkInfo.State.DISCONNECTED || connec.getNetworkInfo(1).getState() == NetworkInfo.State.DISCONNECTED ) {
//Not connected.
//setContentView(status);
tv.setText("The was an error connecting, please try again.");
}
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}