我有一个ArrayList,它会不断被覆盖,而不是向列表中添加新值。我不会在每次只创建一次列表时就重新创建它。如果我手动添加详细信息,该数据不会被覆盖,但是当我尝试按该方法添加时,不会填充数据。所以我不确定是什么问题。这是我完整的Main Activity课堂,所有内容都出现了下降。
public class MainActivity extends AppCompatActivity {
ListView listView;
Button button;
public static final String PREFS_NAME = "MyPreferencesFile";
String date_out,date_in;
String part_number,serial_number;
int employee_number;
Context context;
ArrayList<Toolinfo> toolinfos = new ArrayList<>();
String currentDateandTime;
Toolinfo tool1;
public static String TAG = "Main";
ToolListAdapter myadapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myadapter = new ToolListAdapter(this,R.layout.logrowlayout,toolinfos );
button = findViewById(R.id.button);
listView = findViewById(R.id.listview);
listView.setAdapter(myadapter);
loadData();
//Toolinfo too = new Toolinfo("part number","serial number",333,"date","out");
// Toolinfo too1 = new Toolinfo("part number","serial number",333,"date","out");
// toolinfos.add(too);
// toolinfos.add(too1);
for (int i = 0; i < toolinfos.size() ; i++) {
Log.d(TAG, "onCreate: tools:" + toolinfos.get(i).getPart_number());
}
Intent getData = getIntent();
if(getData.hasExtra("part number")&& getData.hasExtra("serial number") && getData.hasExtra("employee number")) {
final String part_number = getData.getStringExtra("part number");
showToast("has extras");
String serial_number = getData.getStringExtra("serial number");
showToast(serial_number);
int employee_number = getData.getIntExtra("employee number", 0);
populateData(part_number,serial_number,employee_number,date_out,"out");
}else {
showToast("info not present");
}
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
addTool();
}
});
}
public void populateData(String part_number,String serial_number,int employee_number, String date_out, String date_in) {
//loadData();
SimpleDateFormat sdf = new SimpleDateFormat("MMdd");
String currentDateandTime = sdf.format(new Date());
Toolinfo tool = new Toolinfo(part_number, serial_number, employee_number, currentDateandTime, "out");
myadapter.notifyDataSetChanged();
for (int i = 0; i < 1 ; i++) {
//Log.d(TAG, "onCreate: tools:" + toolinfos.get(i).getPart_number());
toolinfos.add(tool);
}
saveData(tool);
}
private void saveData(Toolinfo tool) {
SharedPreferences preferences = getSharedPreferences("Shared prefs", MODE_PRIVATE);
SharedPreferences.Editor editor = preferences.edit();
Gson gson = new Gson();
String json = gson.toJson(tool);
editor.putString("toolobj",json);
showToast(json);
editor.commit();
editor.apply();
showToast("Data Saved");
}
private void loadData(){
SharedPreferences preferences = getSharedPreferences("Shared prefs", MODE_PRIVATE);
Gson gson = new Gson();
String json = preferences.getString("toolobj","");
if (json.isEmpty()){
showToast("no data");
}else {
Toolinfo tool1 = gson.fromJson(json, Toolinfo.class);
if (tool1 != null)
toolinfos.add(tool1);
else{
showToast("Object is null ");
}
}
}
private void addTool(){
Intent i = new Intent(MainActivity.this,Toolsignout.class);
startActivity(i);
//saveData(tool1);
}
public void showToast(String msg){
Toast.makeText(this,msg,Toast.LENGTH_LONG).show();
}
@Override
protected void onResume() {
// loadData();
super.onResume();
}
}
这是arrayadapter类
public class ToolListAdapter extends ArrayAdapter<Toolinfo> {
private Context mcontext;
int mResource;
ArrayList<Toolinfo> objects;
public ToolListAdapter(Context context, int resource, ArrayList<Toolinfo> objects) {
super(context, resource, objects);
mcontext = context;
mResource = resource;
}
@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
String part_number = getItem(position).getPart_number();
String serial_number = getItem(position).getSerial_number();
int employee_number = getItem(position).getEmployee_nummber();
String date_out = getItem(position).getOut_time();
String date_in = getItem(position).getIn_time();
Toolinfo toolinfo = new Toolinfo(part_number,serial_number,employee_number,date_out,date_in);
LayoutInflater layoutInflater = LayoutInflater.from(mcontext);
convertView = layoutInflater.inflate(mResource,parent,false);
TextView parnum = (TextView)convertView.findViewById(R.id.patnum);
TextView sernum = (TextView)convertView.findViewById(R.id.sernum);
TextView empnum = (TextView)convertView.findViewById(R.id.empnum);
TextView timeout = (TextView)convertView.findViewById(R.id.timeout);
TextView timein = (TextView)convertView.findViewById(R.id.timein);
parnum.setText(part_number);
sernum.setText(serial_number);
empnum.setText(String.valueOf(employee_number));
timeout.setText((date_out));
timein.setText((date_in));
return convertView;
}
}
答案 0 :(得分:0)
尽管您的代码不易阅读,但我发现在populateData()
中,您做了一些莫名其妙的事情:
Toolinfo tool = new Toolinfo(part_number, serial_number, employee_number, currentDateandTime, "out");
myadapter.notifyDataSetChanged();
for (int i = 0; i < 1 ; i++) {
//Log.d(TAG, "onCreate: tools:" + toolinfos.get(i).getPart_number());
toolinfos.add(tool);
}
为什么要使用for
循环添加1个元素?和myadapter.notifyDataSetChanged();
应该在添加后调用:
Toolinfo tool = new Toolinfo(part_number, serial_number, employee_number, currentDateandTime, "out");
toolinfos.add(tool);
myadapter.notifyDataSetChanged();
答案 1 :(得分:0)
在适配器中进行以下更改
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
// **added the if else condition**
View listItem = convertView;
if (listItem == null)
{
LayoutInflater layoutInflater = LayoutInflater.from(mcontext);
convertView = layoutInflater.inflate(mResource,parent,false);
}
String part_number = getItem(position).getPart_number();
String serial_number = getItem(position).getSerial_number();
int employee_number = getItem(position).getEmployee_nummber();
String date_out = getItem(position).getOut_time();
String date_in = getItem(position).getIn_time();
Toolinfo toolinfo = new Toolinfo(part_number,serial_number,employee_number,date_out,date_in);
TextView parnum = (TextView)convertView.findViewById(R.id.patnum);
TextView sernum = (TextView)convertView.findViewById(R.id.sernum);
TextView empnum = (TextView)convertView.findViewById(R.id.empnum);
TextView timeout = (TextView)convertView.findViewById(R.id.timeout);
TextView timein = (TextView)convertView.findViewById(R.id.timein);
parnum.setText(part_number);
sernum.setText(serial_number);
empnum.setText(String.valueOf(employee_number));
timeout.setText((date_out));
timein.setText((date_in));
return convertView;
}
我只是将您的充气机放在if语句中
View listItem = convertView;
if (listItem == null)
{
LayoutInflater layoutInflater = LayoutInflater.from(mcontext);
convertView = layoutInflater.inflate(mResource,parent,false);
}