我正在尝试避免列表中的重复值，但它无法正常工作。你可以帮帮我吗？我做了很多工作，但我是android和编码的新手。你能帮我解决我的错误吗？
import java.util.ArrayList;
public class Dynamic extends Activity {
Button bt, bt2, ent, clr;
EditText et, et2;
String input, input1;
public static ArrayList<String> k_listItems = new ArrayList<String>();
public static ArrayList<String> p_listItems = new ArrayList<String>();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bt = (Button) findViewById(R.id.nameok);
et = (EditText) findViewById(R.id.name);
input = et.getText().toString();
bt.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
if (et.getText().length() == 0) {
Context context = getApplicationContext();
CharSequence text = "Enter Your Name";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
} else {
{
for (int i = 0; i < k_listItems.size(); i++) {
if (k_listItems.get(i).equals("input")) {
Intent in = new Intent(Dynamic.this, Dynamic.class);
startActivity(in);
Toast.makeText(getApplicationContext(), "Name Already Exists", Toast.LENGTH_SHORT).show();
break;
}
}
}
if (et.getText().length() == 0) {
Context context = getApplicationContext();
CharSequence text = "Enter Your Number";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
} else {
et2.setVisibility(View.VISIBLE);
bt2.setVisibility(View.VISIBLE);
bt2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (et2.getText().length() == 0) {
Context context = getApplicationContext();
CharSequence text = "Enter Your Number";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
} else {
ent.setVisibility(View.VISIBLE);
clr.setVisibility(View.VISIBLE);
ent.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (null != input && input.length() > 0) {
k_listItems.add(input);
}
if (null != input1 && input1.length() > 0) {
p_listItems.add(input1);
}
input = et.getText().toString();
input1 = et2.getText().toString();
Intent in = new Intent(Dynamic.this, GetList.class);
in.putExtra("input", input);
in.putExtra("input1", input1);
startActivity(in);
}
});
clr.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent in4 = new Intent(Dynamic.this, Dynamic.class);
startActivity(in4);
}
});
}
}
});
}
}
}
});
}
protected void onStart() {
super.onStart();
et2 = (EditText) findViewById(R.id.number);
bt2 = (Button) findViewById(R.id.numberok);
ent = (Button) findViewById(R.id.enter);
clr = (Button) findViewById(R.id.clear);
}
public void onBackPressed() {
Intent startMain = new Intent(Intent.ACTION_MAIN);
startMain.addCategory(Intent.CATEGORY_HOME);
startMain.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(startMain);
}
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
Mylist获取该列表......
import java.util.ArrayList;
public class GetList extends Activity {
ListView lv;
Button bt3;
Dialog d;
EditText edt;
String x;
public static ArrayList<String> x_listItems = new ArrayList<String>();
public static ArrayList<String> y_listItems = new ArrayList<String>();
String inp, inp1;
public static ArrayAdapter<String> a_adapter;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.list);
lv = (ListView) findViewById(R.id.listView1);
Intent in = getIntent();
inp = in.getStringExtra("input");
inp1 = in.getStringExtra("input1");
a_adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, x_listItems);
lv.setAdapter(a_adapter);
if (null != inp && inp.length() > 0) {
x_listItems.add(inp);
a_adapter.notifyDataSetChanged();
}
if (null != inp1 && inp1.length() > 0) {
y_listItems.add(inp1);
Log.v("num", "" + y_listItems);
}
lv.setOnItemClickListener(new OnItemClickListener() {
@SuppressWarnings("deprecation")
@Override
public void onItemClick(AdapterView<?> arg0, View v, int position,
long arg3) {
if (x_listItems.get(position) != null) {
AlertDialog ab = new AlertDialog.Builder(
GetList.this).create();
ab.setTitle("Details");
ab.setMessage("NAME:" + x_listItems.get(position) + "\n" + "Number" + y_listItems.get(position));
ab.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Toast.makeText(getApplicationContext(), "Thanx for visiting", Toast.LENGTH_SHORT).show();
}
});
ab.show();
}
}
});
lv.setOnItemLongClickListener(new OnItemLongClickListener() {
@SuppressWarnings("deprecation")
@Override
public boolean onItemLongClick(AdapterView<?> arg0, View v,
final int position, long arg3) {
if (x_listItems.get(position) != null) {
AlertDialog ab = new AlertDialog.Builder(
GetList.this).create();
ab.setTitle("Slect Your Option");
ab.setButton("Edit", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
final String z = x_listItems.get(position);
Log.v("position", "" + z);
d = new Dialog(GetList.this);
d.setContentView(R.layout.abc);
d.setTitle("Enter new name");
Button sub = (Button) d.findViewById(R.id.submit);
edt = (EditText) d.findViewById(R.id.edt);
edt.setText(x_listItems.get(position));
sub.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
x_listItems.remove(position);
x = edt.getText().toString();
x_listItems.add(position, x);
String p = x_listItems.get(position);
String f = y_listItems.get(position);
y_listItems.set(position, f);
Log.v("changednum", "" + inp1);
a_adapter.notifyDataSetChanged();
lv.setAdapter(a_adapter);
Toast.makeText(getApplicationContext(), "" + edt.getText().toString().trim(), 4000).show();
d.dismiss();
}
});
d.show();
}
});
ab.setButton2("Delete", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
x_listItems.remove(position);
y_listItems.remove(position);
a_adapter.notifyDataSetChanged();
lv.setAdapter(a_adapter);
}
});
ab.show();
}
return true;
}
private int get(int position) {
return 0;
}
});
}
public void onBackPressed() {
super.onBackPressed();
Intent in4 = new Intent(GetList.this, Dynamic.class);
startActivity(in4);
}
}
答案 0 :(得分：4)
设置不允许重复...请参阅下面的示例
HashSet<String> x_hashSet = new HashSet<String>();
HashSet<String> y_hashSet = new HashSet<String>();
x_hashSet.addAll(x_listItems);
y_hashSet.addAll(y_listItems);
x_listItems.clear();
y_listItems.clear();
x_listItems.addAll(x_hashSet);
y_listItems.addAll(y_hashSet);
然后将列表添加到适配器。就是这样。
希望这会对你有帮助;）
答案 1 :(得分：2)
为什么不使用Set代替List？他们不允许重复。如果你把自己的对象放在那里，你将需要一个hashCode和equals方法，但它应该适用于字符串
答案 2 :(得分：1)
HashSet不允许重复值。它提供了添加方法而不是put方法。您还可以使用其contains方法来检查对象是否已在HashSet中可用。可以在想要维护唯一列表的地方使用HashSet。
HashSet<String> stateSet = new HashSet<String>();
stateSet.add ("CA");
stateSet.add ("WI");
stateSet.add ("NY");
if (stateSet.contains("PB")) /* if CA, it will not add but shows following message*/
System.out.println("Already found");
else
stateSet.add("PB");