【发布时间】：2016-04-22 23:43:54
【问题描述】：
我试图制作一个可以预订空置教室的应用程序，但是当我从文件中读取时它很好，但是当我写一个获取空指针引用错误时 它是我试图存储在文件中的字符串，这是我的代码。 当我点击前一个意图的按钮来进入这个意图应用程序崩溃时。但是如果我评论“button.setOnClickListener(new View.OnClickListener()”这个块它工作正常。
public class result extends AppCompatActivity {
Button button;
TextView tv1;
TextView tv2;
TextView tv3;
EditText ed1;
public String f;
public static String[] strarray = new String[3];
public String slot;
public int roomno;
String[] mystr = null;
int i = 0,j;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_result);
Intent intent = getIntent();
f = intent.getExtras().getString("day");
slot=intent.getExtras().getString("time");
tv1 = (TextView) findViewById(R.id.tv1);
tv1.setText(f);
tv1 = (TextView) findViewById(R.id.tv1);
tv2 = (TextView) findViewById(R.id.tv2);
tv3 = (TextView) findViewById(R.id.tv3);
InputStream fin = null;
try {
fin = openFileInput(f);
} catch (FileNotFoundException e1) {
e1.printStackTrace();
}
InputStreamReader ip = new InputStreamReader(fin);
BufferedReader br = new BufferedReader(ip);
int c;
String str = "";
String abc = "";
String def = "";
String xyz = "";
int j=0;
try {
while((str = br.readLine())!= null)
{
String temp[] = str.split(" ");
if (temp[0].compareTo(slot) == 0) {
if(temp[1].compareTo("0") == 0) {
abc = "1301";
tv1.setText(abc);
}
if(temp[2].compareTo("0") == 0) {
def = "1302";
tv2.setText(def);
}
if(temp[3].compareTo("0") == 0) {
xyz = "1303";
tv3.setText(xyz);
}
}
}
} catch (IOException e1) {
e1.printStackTrace();
}
// Toast.makeText(getBaseContext(), "file read", Toast.LENGTH_SHORT).show();
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int i = 0,j;
String line;
try {
BufferedReader br = new BufferedReader(new FileReader(f));
StringBuffer str = new StringBuffer();
while((line = br.readLine()) != null)
{
strarray[i] = line; //Store each line i file in string array.
i++;
}
for(j=0; j<=i; j++)
{
if(j==0) //This i hav taken for 2nd slot (starting from 0)
//make it if(j==timeslot/time-1)
{
String temp = strarray[j];
//temp = trim(temp);
mystr = temp.split(" ",4); //Processing that particular line ka string.
for(int k=0; k<4; k++)
//System.out.println(mystr[k]);
mystr[roomno] = "1"; //Changing from 0 to 1 where classroom = 1301 hence here index=1 in mystr[1] = '1'.
//Make it mystr[roomno] = "1";
str.append(mystr[0]);
str.append(" ");
str.append(mystr[1]);
str.append(" ");
str.append(mystr[2]); //Creating a new changed string
str.append(" ");
str.append(mystr[2]);
strarray[j] = str.toString(); //Since its a buffer convert it to string.
}
}
br.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
FileWriter fileWriter = null;
try {
fileWriter = new FileWriter(f);
} catch (IOException e) {
e.printStackTrace();
}
// Always wrap FileWriter in BufferedWriter.
BufferedWriter b = new BufferedWriter(fileWriter);
for(int m=0; m<3; m++)
{
String temp = strarray[m]; //Write back everything to a file.
try {
b.write(temp);
} catch (IOException e) {
e.printStackTrace();
}
try {
b.newLine();
} catch (IOException e) {
e.printStackTrace();
}
}
try {
b.flush();
} catch (IOException e) {
e.printStackTrace();
}
try {
b.close();
} catch (IOException e) {
e.printStackTrace();
}
}});
}
}
已编辑：logcat
ActivityRecord{bd77102 u0 demo.myapplication/.login t49 f}} 无效；您的活动正在运行吗？ 04-23 05:57:40.028 1298-1317/? W/WindowManager：视图未成功添加到 wm，正在删除视图 04-23 05:57:40.028 1298-1317/? W/WindowManager：添加启动窗口时出现异常 java.lang.IllegalArgumentException: View=com.android.internal.policy.PhoneWindow$DecorView{230ab45 V.E...... R.....ID 0,0-0,0} 未附加到窗口管理器 在 android.view.WindowManagerGlobal.findViewLocked(WindowManagerGlobal.java:424) 在 android.view.WindowManagerGlobal.removeView(WindowManagerGlobal.java:350) 在 android.view.WindowManagerImpl.removeViewImmediate(WindowManagerImpl.java:116) 在 com.android.server.policy.PhoneWindowManager.addStartingWindow(PhoneWindowManager.java:2359) 在 com.android.server.wm.WindowManagerService$H.handleMessage(WindowManagerService.java:7840) 在 android.os.Handler.dispatchMessage(Handler.java:102) 在 android.os.Looper.loop(Looper.java:148) 在 android.os.HandlerThread.run(HandlerThread.java:61) 在 com.android.server.ServiceThread.run(ServiceThread.java:46) 04-23 05:57:40.070 1298-1661/? I/ActivityManager: Killing 2036:com.android.providers.calendar/u0a1 (adj 15): empty for 6000s 04-23 05:57:40.095 2336-2353/? I/OpenGLRenderer：初始化的 EGL，版本 1.4 04-23 05:57:40.097 4016-4016/? W/System：ClassLoader 引用了未知路径：/data/app/demo.myapplication-2/lib/x86 04-23 05:57:40.124 2336-2353/? W/EGL_emulation：eglSurfaceAttrib 未实现 04-23 05:57:40.124 2336-2353/? W/OpenGLRenderer：无法在表面 0xa3818be0 上设置 EGL_SWAP_BEHAVIOR，错误 = EGL_SUCCESS 04-23 05:57:40.177 1298-1426/? W/InputMethodManagerService：得到 RemoteException 向 pid 3978 uid 10060 发送 setActive(false) 通知 04-23 05:57:40.273 1505-2475/? E/Surface：getSlotFromBufferLocked：未知缓冲区：0xb3fd66e0 04-23 05:57:40.785 4034-4034/? D/AndroidRuntime: >>>>>> START com.android.internal.os.RuntimeInit uid 0 >>>>> START com.android.internal.os.RuntimeInit uid 0
【问题讨论】：
-
总是有助于包含确切的错误消息。
标签： android string file file-handling