Java 从不同的活动向ListView添加字符串只会替换第一项,而不会向列表中添加更多项
我正在进行一个项目,该项目允许用户使用按钮将字符串从一个活动发送到另一个活动的列表视图。但是,当我尝试将数据从一个活动发送到下一个活动时,接收活动将替换最后发送的项目,而不是添加到列表视图中。这是我的密码: EnterInfoActivity.java:Java 从不同的活动向ListView添加字符串只会替换第一项,而不会向列表中添加更多项,java,android,listview,Java,Android,Listview,我正在进行一个项目,该项目允许用户使用按钮将字符串从一个活动发送到另一个活动的列表视图。但是,当我尝试将数据从一个活动发送到下一个活动时,接收活动将替换最后发送的项目,而不是添加到列表视图中。这是我的密码: EnterInfoActivity.java: import android.content.Context; import android.content.Intent; import android.content.SharedPreferences; import android.su
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;
import static com.example.kevin.myapplication.R.id.Done;
import static com.example.kevin.myapplication.R.id.EnterInfo;
public class EnterInfoActivity extends AppCompatActivity {
ArrayAdapter<CharSequence> yearAdapter;
Button Done;
EditText Name;
EditText PName;
Spinner YearSpinner;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_enter_info);
Name = (EditText) findViewById(R.id.Name);
PName = (EditText) findViewById(R.id.PName);
Done = (Button) findViewById(R.id.Done);
YearSpinner = (Spinner) findViewById(R.id.Year);
yearAdapter = ArrayAdapter.createFromResource(this,R.array.year_sequence, android.R.layout.simple_spinner_item);
yearAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
YearSpinner.setAdapter(yearAdapter);
Done.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SharedPreferences sharedPreferences = getSharedPreferences("ViewData", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("newName", Name.getText().toString());
editor.putString("newPName", PName.getText().toString());
editor.putString("Year", YearSpinner.getSelectedItem().toString());
editor.commit();
finish();
}
});
}
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.ListViewCompat;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.util.ArrayList;
public class ViewActivity extends AppCompatActivity {
ListView lv;
ArrayList<String> arrayList;
ArrayAdapter<String> adapter;
public static final String DEFAULT = " ";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view);
SharedPreferences sharedPreferences = getSharedPreferences("ViewData", Context.MODE_PRIVATE);
String Name = sharedPreferences.getString("newName",DEFAULT);
String PName = sharedPreferences.getString("newPName",DEFAULT);
String Year = sharedPreferences.getString("Year",DEFAULT);
String PhotoInfo =(Name + " " + PName + " " + Year);
lv = (ListView) findViewById(R.id.LV_View);
arrayList = new ArrayList<String>();
arrayList.add(PhotoInfo);
adapter = new ArrayAdapter<String>(ViewActivity.this, android.R.layout.simple_list_item_1,
arrayList);
lv.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
导入android.content.Context;
导入android.content.Intent;
导入android.content.SharedReferences;
导入android.support.v7.app.AppActivity;
导入android.os.Bundle;
导入android.view.view;
导入android.widget.AdapterView;
导入android.widget.ArrayAdapter;
导入android.widget.Button;
导入android.widget.EditText;
导入android.widget.Spinner;
导入android.widget.Toast;
导入静态com.example.kevin.myapplication.R.id.Done;
导入静态com.example.kevin.myapplication.R.id.EnterInfo;
公共类EnterInfoActivity扩展了AppCompatActivity{
阵列适配器;
按钮完成;
编辑文本名称;
编辑文本PName;
旋转器;旋转器;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u输入信息);
Name=(EditText)findViewById(R.id.Name);
PName=(EditText)findViewById(R.id.PName);
完成=(按钮)findViewById(R.id.Done);
YearSpinner=(Spinner)findViewById(R.id.Year);
yearAdapter=ArrayAdapter.createFromResource(这个,R.array.year\u序列,android.R.layout.simple\u微调器\u项);
yearAdapter.setDropDownViewResource(android.R.layout.simple\u微调器\u下拉菜单\u项);
YearSpinner.setAdapter(yearAdapter);
Done.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
SharedReferences SharedReferences=GetSharedReferences(“ViewData”,Context.MODE\u PRIVATE);
SharedReferences.Editor=SharedReferences.edit();
putString(“newName”,Name.getText().toString());
putString(“newPName”,PName.getText().toString());
putString(“Year”,YearSpinner.getSelectedItem().toString());
commit();
完成();
}
});
}
}
下面是ViewActivity.java:
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;
import static com.example.kevin.myapplication.R.id.Done;
import static com.example.kevin.myapplication.R.id.EnterInfo;
public class EnterInfoActivity extends AppCompatActivity {
ArrayAdapter<CharSequence> yearAdapter;
Button Done;
EditText Name;
EditText PName;
Spinner YearSpinner;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_enter_info);
Name = (EditText) findViewById(R.id.Name);
PName = (EditText) findViewById(R.id.PName);
Done = (Button) findViewById(R.id.Done);
YearSpinner = (Spinner) findViewById(R.id.Year);
yearAdapter = ArrayAdapter.createFromResource(this,R.array.year_sequence, android.R.layout.simple_spinner_item);
yearAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
YearSpinner.setAdapter(yearAdapter);
Done.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SharedPreferences sharedPreferences = getSharedPreferences("ViewData", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString("newName", Name.getText().toString());
editor.putString("newPName", PName.getText().toString());
editor.putString("Year", YearSpinner.getSelectedItem().toString());
editor.commit();
finish();
}
});
}
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.ListViewCompat;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.util.ArrayList;
public class ViewActivity extends AppCompatActivity {
ListView lv;
ArrayList<String> arrayList;
ArrayAdapter<String> adapter;
public static final String DEFAULT = " ";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view);
SharedPreferences sharedPreferences = getSharedPreferences("ViewData", Context.MODE_PRIVATE);
String Name = sharedPreferences.getString("newName",DEFAULT);
String PName = sharedPreferences.getString("newPName",DEFAULT);
String Year = sharedPreferences.getString("Year",DEFAULT);
String PhotoInfo =(Name + " " + PName + " " + Year);
lv = (ListView) findViewById(R.id.LV_View);
arrayList = new ArrayList<String>();
arrayList.add(PhotoInfo);
adapter = new ArrayAdapter<String>(ViewActivity.this, android.R.layout.simple_list_item_1,
arrayList);
lv.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
导入android.content.Context;
导入android.content.Intent;
导入android.content.SharedReferences;
导入android.support.v7.app.AppActivity;
导入android.os.Bundle;
导入android.support.v7.widget.ListViewCompat;
导入android.view.view;
导入android.widget.ArrayAdapter;
导入android.widget.ListView;
导入java.util.ArrayList;
公共类ViewActivity扩展了AppCompatActivity{
ListView lv;
ArrayList ArrayList;
阵列适配器;
公共静态最终字符串DEFAULT=“”;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_视图);
SharedReferences SharedReferences=GetSharedReferences(“ViewData”,Context.MODE\u PRIVATE);
String Name=SharedReferences.getString(“newName”,默认值);
String PName=SharedReferences.getString(“newPName”,默认值);
String Year=SharedReferences.getString(“年”,默认值);
字符串PhotoInfo=(名称+“”+PName+“”+年份);
lv=(ListView)findViewById(R.id.lv\u视图);
arrayList=新的arrayList();
arrayList.add(PhotoInfo);
adapter=new ArrayAdapter(ViewActivity.this、android.R.layout.simple\u list\u item\u 1、,
arrayList);
低压设置适配器(适配器);
adapter.notifyDataSetChanged();
}
}在您的阵列列表中,您总是拥有最后一个阵列。没有要添加到的现有列表,因此它只显示最后一个列表
ArrayList<String> arrayList;
---
arrayList = new ArrayList<String>();
arrayList.add(PhotoInfo);
ArrayList ArrayList;
---
arrayList=新的arrayList();
arrayList.add(PhotoInfo);
从您可以看到的最后两行中,您正在创建一个新列表,并仅向其中添加一个字符串。因此,您可以只看到最后一行。您必须将阵列列表设置为静态,并且不要每次都续订它!您只需创建一次,每次只需向其添加新项并调用notifyDatasetChanged()
公共类ViewActivity扩展了AppCompative活动{
ListView lv;
//将arraylist设置为静态并立即加载。
公共静态ArrayList ArrayList=新建ArrayList();
阵列适配器;
公共静态最终字符串DEFAULT=“”;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_视图);
SharedReferences SharedReferences=GetSharedReferences(“ViewData”,Context.MODE\u PRIVATE);
String Name=SharedReferences.getString(“newName”,默认值);
String PName=SharedReferences.getString(“newPName”,默认值);
String Year=SharedReferences.getString(“年”,默认值);
字符串PhotoInfo=(名称+“”+PName+“”+年份);
lv=(ListView)findViewById(R.id.lv\u视图);
//删除更新阵列列表
arrayList.add(PhotoInfo);
adapter=new ArrayAdapter(ViewActivity.this、android.R.layout.simple\u list\u item\u 1、,
arrayList);
低压设置适配器(适配器);
//没关系
adapter.notifyDataSetChanged();
}
你没有通过一个列表,你只通过了三个我没有通过的列表,并且在你的字符串PhotoInforead中结合了关于Android应用程序生命周期的内容:OnCreate-onStart-onResume…稍后,我建议使用广播接收器
向其他活动可靠地发送数据