在我的应用程序的用户界面中有四个按钮，其中三个按钮（单击时）从mysql数据库中检索图像并将其显示在Android手机中。第四个按钮的工作是从数据库中检索文本。
如果点击任何检索图像的按钮，则首先显示图像。然后，如果单击检索图像的按钮，则显示文本。
但是，当点击显示图像的任何按钮之前，首先点击检索文本的按钮时，应用程序强制关闭!!
检索文本的按钮的onClick活动的代码如下
b.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
Toast.LENGTH_SHORT).show();
try {
data.put("id",id);
} catch (JSONException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
String url="http://10.0.2.2:8080/finder/review/listA";
try {
img.setImageBitmap(null);
json =HTTPPoster.doPost(url, data);
Toast.makeText(getBaseContext(),json.toString(), Toast.LENGTH_SHORT).show();
titles=json.getJSONObject("titles");
Toast.makeText(getBaseContext(), titles.toString(), Toast.LENGTH_SHORT).show();
msgs=json.getJSONObject("msgs");
names=json.getJSONObject("names");
String one=titles.getString("0");
Toast.makeText(getBaseContext(), one.toString(),Toast.LENGTH_LONG).show();
t.setText("\nReviews \n");
String content="";
for(int i=0;i<3;i++)
{
String msg=msgs.getString(i+"");
name=names.getString(i+"");
String title=titles.getString(i+"");
content=t.getText()+("\n Name"+name+"\n Title: "+title+"\n Msg:"+msg);
t.setText(content);
Toast.makeText(getBaseContext(),"Name:"+name+"\n Title: "+title+"\n Message"+msg,Toast.LENGTH_SHORT).show();
}
// t.setText()
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
logcat
06-07 00:25:29.923: INFO/Process(234): Sending signal. PID: 234 SIG: 9
06-07 00:25:30.042: INFO/WindowManager(58): WIN DEATH: Window{44e66ef0 com.lpss/com.lpss.MyList paused=false}
06-07 00:25:30.053: INFO/WindowManager(58): WIN DEATH: Window{44d72da0 com.lpss/com.lpss.lpss paused=false}
06-07 00:25:30.053: INFO/ActivityManager(58): Process com.lpss (pid 234) has died.
06-07 00:25:30.062: WARN/GpsLocationProvider(58): Unneeded remove listener for uid 1000
06-07 00:25:30.062: DEBUG/GpsLocationProvider(58): stopNavigating
06-07 00:25:30.062: INFO/WindowManager(58): WIN DEATH: Window{44dedb10 Toast paused=false}
06-07 00:25:30.091: WARN/ActivityManager(58): Scheduling restart of crashed service com.lpss/.NotifyService in 5000ms
06-07 00:25:30.103: INFO/WindowManager(58): WIN DEATH: Window{44dd9490 com.lpss/com.lpss.Contents paused=false}
06-07 00:25:30.244: INFO/ActivityManager(58): Start proc com.lpss for activity com.lpss/.MyList: pid=248 uid=10030 gids={3003, 1015}
06-07 00:25:30.244: ERROR/ActivityThread(58): Failed to find provider info for android.server.checkin
06-07 00:25:30.244: WARN/Checkin(58): Can't log event SYSTEM_SERVICE_LOOPING: java.lang.IllegalArgumentException: Unknown URL content://android.server.checkin/events
06-07 00:25:30.743: DEBUG/ddm-heap(248): Got feature list request
06-07 00:25:30.912: INFO/UsageStats(58): Unexpected resume of com.lpss while already resumed in com.lpss
06-07 00:25:31.443: WARN/InputManagerService(58): Got RemoteException sending setActive(false) notification to pid 234 uid 10030
06-07 00:25:31.603: INFO/ActivityManager(58): Displayed activity com.lpss/.MyList: 1487 ms (total 1487 ms)
06-07 00:25:31.713: WARN/NotificationService(58): Object died trying to hide notification android.app.ITransientNotification$Stub$Proxy@44de2548 in package com.lpss
06-07 00:25:31.713: WARN/ActivityManager(58): setProcessForeground called on unknown pid: 234
06-07 00:25:31.723: WARN/NotificationService(58): Object died trying to show notification android.app.ITransientNotification$Stub$Proxy@44de2c70 in package com.lpss
06-07 00:25:31.723: WARN/ActivityManager(58): setProcessForeground called on unknown pid: 234
06-07 00:25:31.723: WARN/NotificationService(58): Object died trying to show notification android.app.ITransientNotification$Stub$Proxy@44dd78a0 in package com.lpss
06-07 00:25:31.723: WARN/ActivityManager(58): setProcessForeground called on unknown pid: 234
06-07 00:25:31.723: WARN/NotificationService(58): Object died trying to show notification android.app.ITransientNotification$Stub$Proxy@44dd7fc8 in package com.lpss
06-07 00:25:31.723: WARN/ActivityManager(58): setProcessForeground called on unknown pid: 234
06-07 00:41:25.262: DEBUG/dalvikvm(58): GC freed 19490 objects / 957584 bytes in 209ms
检索图片的代码
b3.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
try {
data.put("name",name);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String url="http://10.0.2.2:8080/finder/place/ph?id="+id;
// json =HTTPPoster.doPost(url, data);
downloadImage(url);
// Toast.makeText(this,json.toString() , Toast.LENGTH_SHORT).show();
}
});
b4.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
t.setText("");
try {
data.put("name",name);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String url="http://10.0.2.2:8080/finder/place/map?id="+id;
// json =HTTPPoster.doPost(url, data);
downloadImage(url);
// Toast.makeText(this,json.toString() , Toast.LENGTH_SHORT).show();
}
});
答案 0 :(得分：0)
我的感觉是空指针错误。我要做的是将整个方法包含在一个大的try{} catch (Throwable t) {}块中。
然后打印出堆栈跟踪和错误消息。事情是你必须调试步骤代码，因为System.out.println（）在android中没有做太多。
（除了：在android中，我已经习惯了使用Log.v（）或类似的东西进行一次性调试代码，在其他平台上你将使用sysout）
或者您可以使用以下内容尝试Android日志框架：
catch (Throwable t)
{
Log.v("Ric_TEST", t.getMessage();
}
然后，您可以在logcat下载中搜索单词“Ric_TEST”。或者（假设您使用Eclipse），您可以通过在。
中键入标记文本来过滤logcat输出另一种类似的方法是使用adb（adb logcat -v time）连接到您的设备，您可以观看日志，并在应用崩溃时查看堆栈跟踪。
请注意：一旦发现错误，请删除我提到的try..catch块 - 我只是提倡它作为查找错误的工具。