您好如何获取学生姓名包含n个值，我想将所有值存储在一个数组中。因为我想获得所有n个学生姓名值。
因为我创建了两个数组如果我正在运行它给出了不幸的错误。我想存储存储到数据库的所有学生名称。
java文件：
public class Attend extends Activity implements OnClickListener {
String data = "";
TableLayout tl;
TableRow tr;
TextView studentName;
EditText Firstname,stRoll1;
CheckBox present;
String[] class_name, section_name;
EditText[] studentNames= new EditText[500];
EditText[] rollNos= new EditText[500];
int j=0;
@SuppressLint("NewApi")
String student_name[],roll_no;
Button save;
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tl = (TableLayout) findViewById(R.id.maintable);
save = (Button)findViewById(R.id.save);
studentNames[j] = (EditText) findViewById(R.id.studentname );
studentNames[j].setVisibility(View.GONE);
stRoll1 = (EditText) findViewById(R.id.rollnumber );
stRoll1.setVisibility(View.GONE);
save.setOnClickListener(new View.OnClickListener() {
@TargetApi(Build.VERSION_CODES.GINGERBREAD)
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
//save.setText("Record Saved Sucessfully");
student_name[j] = studentNames[j].getText().toString();
System.out.println(student_name[j]);
roll_no = stRoll1.getText().toString();
System.out.println(roll_no);
Toast.makeText(
Attend.this,
"Result : " + "\nStudentName : " +student_name
+ "\nRollno : " + roll_no,
Toast.LENGTH_SHORT).show();
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("student_name",student_name[j]));
nameValuePairs.add(new BasicNameValuePair("roll_no",roll_no));
// nameValuePairs.add(new BasicNameValuePair("f3",v3));
StrictMode.setThreadPolicy(policy);
final String queryString = "student_name=" + student_name+ "&roll_no=" + roll_no;
data = DatabaseUtility.executeQueryPhp("save",queryString);
System.out.println(data);
}
});
String class_id = getIntent().getStringExtra("class_id");
String section_id = getIntent().getStringExtra("section_id");
Toast.makeText(
this,
"Result : " + "\nclassName : " + class_id + "\nSectionName : "
+ section_id,
Toast.LENGTH_SHORT).show();
final String queryString = "class_id=" + class_id + "§ion_id="
+ section_id;
/*String result = DatabaseUtility.executeQueryPhp("getStudent",
queryString);*/
new Thread(new Runnable() {
public void run() {
data = DatabaseUtility.executeQueryPhp("getStudent",queryString);
System.out.println(data);
runOnUiThread(new Runnable() {
@Override
public void run() {
ArrayList<StudentDetails> users = parseJSON(data);
addData(users);
}
});
}
}).start();
}
public ArrayList<StudentDetails> parseJSON(String result) {
ArrayList<StudentDetails> users = new ArrayList<StudentDetails>();
try {
JSONArray jArray = new JSONArray(result);
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
StudentDetails user = new StudentDetails();
// user.setId(json_data.getInt("class_name"));
// user.setClass_id(json_data.getInt("section_name"));
// user.setSection_id(json_data.getInt("section_id"));
user.setStudentname(json_data.getString("first_name"));
user.setRollno(json_data.getString("roll_no"));
users.add(user);
}
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
return users;
}
void addHeader() {
tr = new TableRow(this);
studentName = new TextView(this);
studentName.setText("StudentName");
studentName.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
studentName.setPadding(5, 5, 5, 5);
studentName.setBackgroundColor(Color.RED);
LinearLayout Ll = new LinearLayout(this);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
params.setMargins(5, 5, 5, 5);
Ll.addView(studentName, params);
tr.addView((View) Ll);
TextView RollNo = new TextView(this);
RollNo.setText("RollNo");
RollNo.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
RollNo.setPadding(5, 5, 5, 5);
RollNo.setBackgroundColor(Color.RED);
Ll = new LinearLayout(this);
params = new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT);
params.setMargins(0, 5, 5, 5);
Ll.addView(RollNo, params);
tr.addView((View) Ll);
TextView Present = new TextView(this);
Present.setText("Present");
Present.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
Present.setPadding(5, 5, 5, 5);
Present.setBackgroundColor(Color.RED);
Ll = new LinearLayout(this);
params = new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT);
params.setMargins(0, 5, 5, 5);
Ll.addView(Present, params);
tr.addView((View) Ll);
tl.addView(tr, new TableLayout.LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
}
@SuppressWarnings({ "rawtypes" })
public void addData(ArrayList<StudentDetails> users) {
addHeader();
for (Iterator i = users.iterator(); i.hasNext();) {
StudentDetails p = (StudentDetails) i.next();
/** Create a TableRow dynamically **/
tr = new TableRow(this);
/** Creating a TextView to add to the row **/
studentNames[j] = new EditText(this);
studentNames[j].setKeyListener(null);
/*int[] ids = new int[]{R.id.studentname,R.id.rollnumber};//and so on
for(intE id : ids){
//EditText t = (EditText) findViewById(id);
st=studentNames.add(Firstname.getText().toString());
}
*/
studentNames[j].setText(p.getStudentname());
studentNames[j].setId(p.getId());
studentNames[j].setLayoutParams(new LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
studentNames[j].setPadding(5, 5, 5, 5);
LinearLayout Ll = new LinearLayout(this);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
params.setMargins(5, 2, 2, 2);
Ll.addView(studentNames[j], params);
tr.addView((View) Ll);
stRoll1= new EditText(this);
//stva = n.add(stRoll1.getText().toString());
stRoll1.setKeyListener(null);
stRoll1.setText(p.getRollno());
stRoll1.setLayoutParams(new LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
stRoll1.setPadding(5, 5, 5, 5);
Ll = new LinearLayout(this);
params = new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT);
params.setMargins(0, 3, 3, 3);
Ll.addView(stRoll1, params);
tr.addView((View) Ll);
CheckBox present = new CheckBox(this);
present.setLayoutParams(new LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
present.setPadding(5, 5, 5, 5);
Ll = new LinearLayout(this);
params = new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT);
params.setMargins(0, 3, 3, 3);
Ll.addView(present, params);
tr.addView((View) Ll);
tl.addView(tr, new TableLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));
}
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
logcat
09-23 08:52:20.964: E/AndroidRuntime(2633): java.lang.NullPointerException
09-23 08:52:20.964: E/AndroidRuntime(2633): at com.rushda.attendance.Attend$1.onClick(Attend.java:85)
09-23 08:52:20.964: E/AndroidRuntime(2633): at android.view.View.performClick(View.java:4438)
09-23 08:52:20.964: E/AndroidRuntime(2633): at android.view.View$PerformClick.run(View.java:18422)
09-23 08:52:20.964: E/AndroidRuntime(2633): at android.os.Handler.handleCallback(Handler.java:733)
09-23 08:52:20.964: E/AndroidRuntime(2633): at android.os.Handler.dispatchMessage(Handler.java:95)
09-23 08:52:20.964: E/AndroidRuntime(2633): at android.os.Looper.loop(Looper.java:136)
09-23 08:52:20.964: E/AndroidRuntime(2633): at android.app.ActivityThread.main(ActivityThread.java:5017)
09-23 08:52:20.964: E/AndroidRuntime(2633): at java.lang.reflect.Method.invokeNative(Native Method)
09-23 08:52:20.964: E/AndroidRuntime(2633): at java.lang.reflect.Method.invoke(Method.java:515)
09-23 08:52:20.964: E/AndroidRuntime(2633): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
09-23 08:52:20.964: E/AndroidRuntime(2633): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
09-23 08:52:20.964: E/AndroidRuntime(2633): at dalvik.system.NativeStart.main(Native Method)