我正在尝试使用Remove duplicates from a Json String in Java?问题的答案从json字符串中删除重复项，但它无效。这是我的代码
inquire.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//location = loc.getText().toString();
StringRequest request = new StringRequest(Request.Method.POST, urlRec, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
String responseString = response.toString();
JSONObject obj = new JSONObjectIgnoreDuplicates(responseString);
JSONArray recJsonArray = obj.getJSONArray("search");
// JSONArray recJsonArray = new JSONArray(responseString);
List<Recipient> recList = new ArrayList<>();
for (int i = 0; i < recJsonArray.length(); i++) {
JSONObject recJsonObj = (JSONObject) recJsonArray.get(i);
Recipient rec = new Recipient();
rec.setname(recJsonObj.getString("name"));
rec.setLocation(recJsonObj.getString("location"));
rec.setcontact(recJsonObj.getString("contact"));
recList.add(rec);
}
Intent myintent = new Intent(Search_inq.this, Reclist.class);
myintent.putExtra("recList", (Serializable) recList);
startActivity(myintent);
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.e("Error", error.getMessage());
Toast.makeText(getApplication(), "Error occurred", Toast.LENGTH_LONG).show();
}
}) {
@Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> parameters = new HashMap<>();
parameters.put("location", location);
return parameters;
}
};
queue.add(request);
}
});
在这里，我进行查询的表格称为SEARCH。如果可以请帮助。
修改
这是JSONObjectIgnoreDuplicates类的代码
public class JSONObjectIgnoreDuplicates extends JSONObject {
public JSONObjectIgnoreDuplicates(String json) throws JSONException {
super(json);
}
public JSONObject putOnce(String key, Object value) throws JSONException {
Object storedValue;
if (key != null && value != null) {
if ((storedValue = this.opt(key)) != null ) {
if(!storedValue.equals(value)) //Only through Exception for different values with same key
Log.d("not accepted","n");
else
return this;
}
this.put(key, value);
}
return this;
}
}
编辑 -
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_reclist);
Intent i = getIntent();
// List<Recipient> recList = (List<Recipient>) i.getParcelableArrayListExtra("recList");
ArrayList<Recipient> recList = getIntent().getParcelableArrayListExtra("recList");
list = (ListView) findViewById(R.id.list1);
onLoaded(recList);
}
public void onLoaded(List<Recipient> recList) {
for (Recipient rec : recList) {
HashMap<String, String> map = new HashMap<>();
map.put("name", rec.getUserName());
map.put("location", rec.getLocation());
map.put("contact", rec.getContact());
recplist.add(map);
}
loadListView();
}
private void loadListView() {
ListAdapter adapter = new SimpleAdapter(Reclist.this, recplist, R.layout.list_item,
new String[]{"name", "location", "contact"},
new int[]{R.id.textView3, R.id.textView4, R.id.textView6});
list.setAdapter(adapter);
}
答案 0 :(得分：0)
为您的Recipient类创建一个等于和哈希码的覆盖，并且在它的同时使它实现Parcelable，因为它比可序列化更快。例如：
public class Recipient implements Parcelable {
private String name, location, contact;
public Recipient(String name, String location, String contact) {
this.name = name;
this.location = location;
this.contact = contact;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getLocation() {
return location;
}
public void setLocation(String location) {
this.location = location;
}
public String getContact() {
return contact;
}
public void setContact(String contact) {
this.contact = contact;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Recipient recipient = (Recipient) o;
if (name != null ? !name.equals(recipient.name) : recipient.name != null) return false;
if (location != null ? !location.equals(recipient.location) : recipient.location != null)
return false;
return contact != null ? contact.equals(recipient.contact) : recipient.contact == null;
}
@Override
public int hashCode() {
int result = name != null ? name.hashCode() : 0;
result = 31 * result + (location != null ? location.hashCode() : 0);
result = 31 * result + (contact != null ? contact.hashCode() : 0);
return result;
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(this.name);
dest.writeString(this.location);
dest.writeString(this.contact);
}
protected Recipient(Parcel in) {
this.name = in.readString();
this.location = in.readString();
this.contact = in.readString();
}
public static final Parcelable.Creator<Recipient> CREATOR = new Parcelable.Creator<Recipient>() {
@Override
public Recipient createFromParcel(Parcel source) {
return new Recipient(source);
}
@Override
public Recipient[] newArray(int size) {
return new Recipient[size];
}
};
}
然后您的实现可以如下，因为Recipient类可以通过ArrayList#contains方法进行比较：
try {
String responseString = response.toString();
JSONObject object = new JSONObject(responseString);
JSONArray recJsonArray = object.getJSONArray("search");
ArrayList<Recipient> recList = new ArrayList<>();
for (int i = 0; i < recJsonArray.length(); i++) {
JSONObject recJsonObj = (JSONObject) recJsonArray.get(i);
Recipient rec = new Recipient(recJsonObj.getString("name"),
recJsonObj.getString("location"),
recJsonObj.getString("contact"));
if (!recList.contains(rec)) {
// if it isn't already there, add it
recList.add(rec);
}
}
Intent myintent = new Intent(Search_inq.this, Reclist.class);
//use putParcelableArrayListExtra since its faster than serializable
myintent.putParcelableArrayListExtra("recList", recList);
startActivity(myintent);
} catch (JSONException e) {
Log.e("some tag", e.getMessage(), e);
}
要从新活动中使用意图中获取数据：
ArrayList<Recipient> recList = getIntent().getParcelableArrayListExtra("recList");