我应该如何计算ArrayList字符串从Listview值到ArrayList Integer和返回Listview，因为我一直在为Android应用程序，计算Listview项目，这是从ArrayList。这是我最讨厌的一个，它显示了textView的最后一个arrayList值，而不是计算它们
public class Menu extends AppCompatActivity {
public FloatingActionButton fab1, fab2, fab3;
public Animation fab_open, fab_close, rotate_cw, rotate_ccw;
public EditText editText, editText2, editText3, editText4;
public TextView textView1;
public ListView listView;
public ArrayList<String> arrayList;
public ArrayAdapter<String> arrayAdapter;
public boolean isOpen = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_menu);
fab1 = findViewById(R.id.fab_1);
fab2 = findViewById(R.id.fab_2);
fab3 = findViewById(R.id.fab_3);
textView1 = findViewById(R.id.info_text4);
listView = findViewById(R.id.listview_items);
fab_open = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.fab_open);
fab_close = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.fab_close);
rotate_cw = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.rotate_cw);
rotate_ccw = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.rotate_ccw);
loadData();
calculate();
arrayAdapter = new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_list_item_1, arrayList);
listView.setAdapter(arrayAdapter);
fab1.setOnClickListener(view -> {
if (isOpen) {
fab2.startAnimation(fab_close);
fab3.startAnimation(fab_close);
fab1.startAnimation(rotate_cw);
fab2.setClickable(true);
fab3.setClickable(true);
isOpen = false;
} else {
fab2.startAnimation(fab_open);
fab3.startAnimation(fab_open);
fab1.startAnimation(rotate_ccw);
fab2.setClickable(true);
fab3.setClickable(true);
isOpen = true;
}
});
// Budget
fab2.setOnClickListener(view -> {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Add Budget");
builder.setIcon(R.drawable.ic_wallet_budget);
final View customLayout = getLayoutInflater().inflate(R.layout.add_budget_popup, null);
builder.setView(customLayout);
builder.setPositiveButton("OK", (dialog, which) -> {
// Budget Name
editText = customLayout.findViewById(R.id.editText);
// Budget Input
editText2 = customLayout.findViewById(R.id.editText2);
// Conditional Statements
if(TextUtils.isEmpty(editText.getText().toString()) && TextUtils.isEmpty(editText2.getText().toString())) {
Toast toast = Toast.makeText(getApplicationContext(), "No Budget Name Data and No Budget Data been added", Toast.LENGTH_SHORT);
toast.show();
} else if(TextUtils.isGraphic(editText.getText().toString()) && TextUtils.isEmpty(editText2.getText().toString())){
Toast toast = Toast.makeText(getApplicationContext(), "Budget Name Data has a input, but No Budget Data input", Toast.LENGTH_SHORT);
toast.show();
} else if(TextUtils.isEmpty(editText.getText().toString()) && TextUtils.isDigitsOnly(editText2.getText().toString())){
Toast toast = Toast.makeText(getApplicationContext(), "Budget Data input has a input, but No Budget Name Data input", Toast.LENGTH_SHORT);
toast.show();
} else {
arrayList.add(editText2.getText().toString());
arrayAdapter.notifyDataSetChanged();
Toast toast = Toast.makeText(getApplicationContext(), "Budget Data Added", Toast.LENGTH_SHORT);
toast.show();
saveData();
}
});
AlertDialog dialog = builder.create();
dialog.show();
dialog.setCancelable(false);
});
// Expense
fab3.setOnClickListener(view -> {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Add Expense");
builder.setIcon(R.drawable.ic_money_exp);
final View customLayout = getLayoutInflater().inflate(R.layout.add_expense_popup, null);
builder.setView(customLayout);
builder.setPositiveButton("OK", (dialog, which) -> {
// Expense Name
editText3 = customLayout.findViewById(R.id.editText3);
// Expense Input
editText4 = customLayout.findViewById(R.id.editText4);
// Conditional Statements
if(TextUtils.isEmpty(editText3.getText().toString()) && TextUtils.isEmpty(editText4.getText().toString())) {
Toast toast = Toast.makeText(getApplicationContext(), "No Expense Name Data and No Expense Data been added", Toast.LENGTH_SHORT);
toast.show();
} else if(TextUtils.isGraphic(editText3.getText().toString()) && TextUtils.isEmpty(editText4.getText().toString())){
Toast toast = Toast.makeText(getApplicationContext(), "Expense Name Data has a input, but No Expense Data input", Toast.LENGTH_SHORT);
toast.show();
} else if(TextUtils.isEmpty(editText3.getText().toString()) && TextUtils.isDigitsOnly(editText4.getText().toString())){
Toast toast = Toast.makeText(getApplicationContext(), "Expense Data input has a input, but No Expense Name Data input", Toast.LENGTH_SHORT);
toast.show();
} else {
arrayList.add(editText4.getText().toString());
arrayAdapter.notifyDataSetChanged();
Toast toast = Toast.makeText(getApplicationContext(), "Expense Data Added", Toast.LENGTH_SHORT);
toast.show();
saveData();
}
});
AlertDialog dialog = builder.create();
dialog.show();
dialog.setCancelable(false);
});
}
private void saveData() {
SharedPreferences sharedPreferences = getSharedPreferences("SHAREDPREFS", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
Gson gson = new Gson();
String json = gson.toJson(arrayList);
editor.putString("Test", json);
editor.apply();
}
private void loadData(){
SharedPreferences sharedPreferences = getSharedPreferences("SHAREDPREFS", MODE_PRIVATE);
Gson gson = new Gson();
String json = sharedPreferences.getString("Test", null);
Type type = new TypeToken<ArrayList<String>>(){}.getType();
arrayList = gson.fromJson(json, type);
if(arrayList == null){
arrayList = new ArrayList<>();
}
}
private void calculate(){
for (int i = 0; i < arrayList.size(); i++) {
textView1.setText(String.valueOf(arrayList.get(i)));
}
}
@Override
public boolean onCreateOptionsMenu(android.view.Menu menu){
getMenuInflater().inflate(R.menu.list, menu);
return true;
}
@SuppressLint("NonConstantResourceId")
@Override
public boolean onOptionsItemSelected(MenuItem items){
switch (items.getItemId()){
case R.id.items:
// Email Feedback System
Intent intent=new Intent(Intent.ACTION_SEND);
String[] recipients={"companyenode@gmail.com"};
intent.putExtra(Intent.EXTRA_EMAIL, recipients);
intent.putExtra(Intent.EXTRA_SUBJECT,"Subject text here...");
intent.putExtra(Intent.EXTRA_TEXT,"Body of the content here...");
intent.putExtra(Intent.EXTRA_CC,"mailcc@gmail.com");
intent.setType("text/html");
intent.setPackage("com.google.android.gm");
startActivity(Intent.createChooser(intent, "Send mail"));
case R.id.items3:
// About App
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("About");
builder.setIcon(R.drawable.ic_baseline_info_24);
builder.setMessage("Our app allows you to monitor and categorize your expenses across different bank and investment accounts and credit cards, our app also offer budgeting tools, credit monitoring, mileage tracking, receipt keeping, and advice to grow your net worth.");
builder.setCancelable(false);
builder.setPositiveButton("Close", (dialog, id) -> dialog.cancel());
AlertDialog alert = builder.create();
alert.show();
default:
return super.onOptionsItemSelected(items);
}
}
@Override
public void onBackPressed() {
new AlertDialog.Builder(this).
setIcon(android.R.drawable.ic_dialog_alert)
.setTitle("Exit")
.setMessage("Are you sure you want to close app?")
.setPositiveButton("Yes", (dialog, which) -> finish())
.setNegativeButton("No", null)
.show();
}
}
这是我的问题，我的代码有问题吗?
问题出在这个函数
private void calculate(){
for (int i = 0; i < arrayList.size(); i++) {
textView1.setText(String.valueOf(arrayList.get(i)));
}
}
循环遍历数组列表，并按顺序将文本设置为每个数组列表项。这意味着它将覆盖之前的任何文本，最终只显示最后一个条目。如果你的数组列表是["1","2","3"]，这和调用
testView1.setText("1");
testView1.setText("2"); // overrides the "1"
testView1.setText("3"); // overrides the "2"
// ends with it showing "3"
如果你想显示所有数组项的和，你应该先计算和，然后显示它，像这样:
private void calculate() {
// first calculate the total
int total = 0;
for (int i = 0; i < arrayList.size(); i++) {
total += Integer.parseInt(arrayList.get(i));
}
// then display it
textView1.setText(String.valueOf(total));
}
如果数组列表中的任何数字不是整数，这将在调用parseInt时抛出NumberFormatException，所以如果有可能，您应该添加一些异常处理
private void calculate() {
int total = 0;
for (int i = 0; i < arrayList.size(); i++) {
try {
total += Integer.parseInt(arrayList.get(i));
} catch( NumberFormatException e) {
e.printStackTrace();
}
}
textView1.setText(String.valueOf(total));
}