我正在开发一个概念验证应用程序,以便我可以在我正在制作的更大的应用程序中实现该功能.我对Java和Android Dev有点新鲜,但希望这不应该是一个简单或复杂的问题.
基本上,我正在尝试从CSV文件中读取字符串列表,并使其可用于在应用程序的主要活动上显示列表.
我正在使用外部类来读取CSV.这是类代码:
CSVFile.java
package com.yourtechwhiz.listdisplay;
import android.util.Log;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
public class CSVFile {
InputStream inputStream;
public CSVFile(InputStream inputStream){
this.inputStream = inputStream;
}
public List read(){
List resultList = new ArrayList();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
try {
String csvLine;
while ((csvLine = reader.readLine()) != null) {
String[] row = csvLine.split(",");
resultList.add(row);
Log.d("VariableTag", row[0].toString());
}
}
catch (IOException ex) {
throw new RuntimeException("Error in reading CSV file: "+ex);
}
finally {
try {
inputStream.close();
}
catch (IOException e) {
throw new RuntimeException("Error while closing input stream: "+e);
}
}
return resultList;
}
}
这是我的主要活动代码:
MainActivity.java
package com.yourtechwhiz.listdisplay;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
// Array of strings that's used to display on screen
String[] mobileArray = {"Android","IPhone","WindowsMobile","Blackberry",
"WebOS","Ubuntu","Windows7","Max OS X"};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
prepArray();
//Display List on Activity
ArrayAdapter adapter = new ArrayAdapter<String>(this,
R.layout.activity_listview, mobileArray);
ListView listView = (ListView) findViewById(R.id.mobile_list);
listView.setAdapter(adapter);
}
//Get list of strings from CSV ready to use
private void prepArray() {
InputStream inputStream = getResources().openRawResource(R.raw.strings);
CSVFile csvFile = new CSVFile(inputStream);
List myList = csvFile.read();
//This is where it has an error
//Set first array in myList to this new array myArray
String[] myArray = myList.get(0);
}
}
我实际上还没有设置mobileArray数组.现在我只是想从List对象myList中"提取"信息...
有人可以向我解释这是如何完成的吗？也许我只是不完全理解List类型.看起来当在CSVFile读取方法中返回resultList时,它将作为由String数组对象组成的List对象返回.但我似乎无法让它像那样工作.
任何帮助表示赞赏!
最终编辑(工作代码)
private void prepArray() {
try{
CSVReader reader = new CSVReader(new InputStreamReader(getResources().openRawResource(R.raw.strings)));//Specify asset file name
String [] nextLine;
while ((nextLine = reader.readNext()) != null) {
// nextLine[] is an array of values from the line
System.out.println(nextLine[0] + nextLine[1] + "etc...");
Log.d("VariableTag", nextLine[0]);
}
}catch(Exception e){
e.printStackTrace();
Toast.makeText(this, "The specified file was not found", Toast.LENGTH_SHORT).show();
}
}
编辑
现在我的prepArray函数如下所示:
private void prepArray() {
try{
String csvfileString = this.getApplicationInfo().dataDir + File.separatorChar + "strings.csv"
File csvfile = new File(csvfileString);
CSVReader reader = new CSVReader(new FileReader("csvfile.getAbsolutePath()"));
String [] nextLine;
while ((nextLine = reader.readNext()) != null) {
// nextLine[] is an array of values from the line
System.out.println(nextLine[0] + nextLine[1] + "etc...");
}
}catch(FileNotFoundException e){
e.printStackTrace();
Toast.makeText(this, "The specified file was not found", Toast.LENGTH_SHORT).show();
}
}
仍然产生FileNotFoundException.
编辑2/3
这是我在实际手机上运行应用程序时生成的日志,其中strings.csv位于字符串的子文件夹(src\main\assets\strings\strings.csv)中,并且您对代码请求了更改:
03/27 17:44:01: Launching app
$ adb push C:\Users\Roy\AndroidStudioProjects\ListDisplay\app\build\outputs\apk\app-debug.apk /data/local/tmp/com.yourtechwhiz.listdisplay
$ adb shell pm install -r "/data/local/tmp/com.yourtechwhiz.listdisplay"
pkg: /data/local/tmp/com.yourtechwhiz.listdisplay
Success
$ adb shell am start -n "com.yourtechwhiz.listdisplay/com.yourtechwhiz.listdisplay.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER -D
Connecting to com.yourtechwhiz.listdisplay
D/HyLog: I : /data/font/config/sfconfig.dat, No such file or directory (2)
D/HyLog: I : /data/font/config/dfactpre.dat, No such file or directory (2)
D/HyLog: I : /data/font/config/sfconfig.dat, No such file or directory (2)
W/ActivityThread: Application com.yourtechwhiz.listdisplay is waiting for the debugger on port 8100...
I/System.out: Sending WAIT chunk
I/dalvikvm: Debugger is active
I/System.out: Debugger has connected
I/System.out: waiting for debugger to settle...
Connected to the target VM, address: 'localhost:8609', transport: 'socket'
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: waiting for debugger to settle...
I/System.out: debugger has settled (1498)
I/dalvikvm: Could not find method android.view.Window$Callback.onProvideKeyboardShortcuts, referenced from method android.support.v7.view.WindowCallbackWrapper.onProvideKeyboardShortcuts
W/dalvikvm: VFY: unable to resolve interface method 16152: Landroid/view/Window$Callback;.onProvideKeyboardShortcuts (Ljava/util/List;Landroid/view/Menu;I)V
D/dalvikvm: VFY: replacing opcode 0x72 at 0x0002
W/dalvikvm: VFY: unable to find class referenced in signature (Landroid/view/SearchEvent;)
I/dalvikvm: Could not find method android.view.Window$Callback.onSearchRequested, referenced from method android.support.v7.view.WindowCallbackWrapper.onSearchRequested
W/dalvikvm: VFY: unable to resolve interface method 16154: Landroid/view/Window$Callback;.onSearchRequested (Landroid/view/SearchEvent;)Z
D/dalvikvm: VFY: replacing opcode 0x72 at 0x0002
I/dalvikvm: Could not find method android.view.Window$Callback.onWindowStartingActionMode, referenced from method android.support.v7.view.WindowCallbackWrapper.onWindowStartingActionMode
W/dalvikvm: VFY: unable to resolve interface method 16158: Landroid/view/Window$Callback;.onWindowStartingActionMode (Landroid/view/ActionMode$Callback;I)Landroid/view/ActionMode;
D/dalvikvm: VFY: replacing opcode 0x72 at 0x0002
I/dalvikvm: Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.widget.TintTypedArray.getChangingConfigurations
W/dalvikvm: VFY: unable to resolve virtual method 455: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
D/dalvikvm: VFY: replacing opcode 0x6e at 0x0002
I/dalvikvm: Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.widget.TintTypedArray.getType
W/dalvikvm: VFY: unable to resolve virtual method 477: Landroid/content/res/TypedArray;.getType (I)I
D/dalvikvm: VFY: replacing opcode 0x6e at 0x0008
I/dalvikvm: Could not find method android.widget.FrameLayout.startActionModeForChild, referenced from method android.support.v7.widget.ActionBarContainer.startActionModeForChild
W/dalvikvm: VFY: unable to resolve virtual method 16589: Landroid/widget/FrameLayout;.startActionModeForChild (Landroid/view/View;Landroid/view/ActionMode$Callback;I)Landroid/view/ActionMode;
D/dalvikvm: VFY: replacing opcode 0x6f at 0x0002
I/dalvikvm: Could not find method android.content.Context.getColorStateList, referenced from method android.support.v7.content.res.AppCompatResources.getColorStateList
W/dalvikvm: VFY: unable to resolve virtual method 269: Landroid/content/Context;.getColorStateList (I)Landroid/content/res/ColorStateList;
D/dalvikvm: VFY: replacing opcode 0x6e at 0x0006
I/dalvikvm: Could not find method android.content.res.Resources.getDrawable, referenced from method android.support.v7.widget.ResourcesWrapper.getDrawable
W/dalvikvm: VFY: unable to resolve virtual method 418: Landroid/content/res/Resources;.getDrawable (ILandroid/content/res/Resources$Theme;)Landroid/graphics/drawable/Drawable;
D/dalvikvm: VFY: replacing opcode 0x6e at 0x0002
I/dalvikvm: Could not find method android.content.res.Resources.getDrawableForDensity, referenced from method android.support.v7.widget.ResourcesWrapper.getDrawableForDensity
W/dalvikvm: VFY: unable to resolve virtual method 420: Landroid/content/res/Resources;.getDrawableForDensity (IILandroid/content/res/Resources$Theme;)Landroid/graphics/drawable/Drawable;
D/dalvikvm: VFY: replacing opcode 0x6e at 0x0002
E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering
W/dalvikvm: VFY: unable to resolve instanceof 140 (Landroid/graphics/drawable/RippleDrawable;) in Landroid/support/v7/widget/AppCompatImageHelper;
D/dalvikvm: VFY: replacing opcode 0x20 at 0x000c
W/System.err: java.io.FileNotFoundException: /csvfile.getAbsolutePath(): open failed: ENOENT (No such file or directory)
W/System.err: at libcore.io.IoBridge.open(IoBridge.java:462)
W/System.err: at java.io.FileInputStream.<init>(FileInputStream.java:78)
W/System.err: at java.io.FileInputStream.<init>(FileInputStream.java:105)
W/System.err: at java.io.FileReader.<init>(FileReader.java:66)
W/System.err: at com.yourtechwhiz.listdisplay.MainActivity.prepArray(MainActivity.java:43)
W/System.err: at com.yourtechwhiz.listdisplay.MainActivity.onCreate(MainActivity.java:26)
W/System.err: at android.app.Activity.performCreate(Activity.java:5287)
W/System.err: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
W/System.err: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2145)
W/System.err: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2231)
W/System.err: at android.app.ActivityThread.access$700(ActivityThread.java:139)
W/System.err: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1401)
W/System.err: at android.os.Handler.dispatchMessage(Handler.java:102)
W/System.err: at android.os.Looper.loop(Looper.java:137)
W/System.err: at android.app.ActivityThread.main(ActivityThread.java:5082)
W/System.err: at java.lang.reflect.Method.invokeNative(Native Method)
W/System.err: at java.lang.reflect.Method.invoke(Method.java:515)
W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782)
W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:598)
W/System.err: at dalvik.system.NativeStart.main(Native Method)
W/System.err: Caused by: libcore.io.ErrnoException: open failed: ENOENT (No such file or directory)
W/System.err: at libcore.io.Posix.open(Native Method)
W/System.err: at libcore.io.BlockGuardOs.open(BlockGuardOs.java:110)
W/System.err: at libcore.io.IoBridge.open(IoBridge.java:446)
W/System.err: ... 19 more
I/Adreno-EGL: <qeglDrvAPI_eglInitialize:385>: EGL 1.4 QUALCOMM build: ()
OpenGL ES Shader Compiler Version: E031.24.00.01
Build Date: 12/27/13 Fri
Local Branch: qualcomm_only
Remote Branch:
Local Patches:
Reconstruct Branch:
D/OpenGLRenderer: Enabling debug mode 0
D/OpenGLRenderer: GL error from OpenGLRenderer: 0x502
E/OpenGLRenderer: GL_INVALID_OPERATION
bur*_*add 23
试试OpenCSV - 它会让你的生活更轻松.
首先,将此包添加到gradle依赖项中,如下所示
implementation 'com.opencsv:opencsv:4.6'
然后你可以做到
import com.opencsv.CSVReader;
import java.io.IOException;
import java.io.FileReader;
...
try {
CSVReader reader = new CSVReader(new FileReader("yourfile.csv"));
String[] nextLine;
while ((nextLine = reader.readNext()) != null) {
// nextLine[] is an array of values from the line
System.out.println(nextLine[0] + nextLine[1] + "etc...");
}
} catch (IOException e) {
}
要么
CSVReader reader = new CSVReader(new FileReader("yourfile.csv"));
List myEntries = reader.readAll();
try {
File csvfile = new File(Environment.getExternalStorageDirectory() + "/csvfile.csv");
CSVReader reader = new CSVReader(new FileReader("csvfile.getAbsolutePath()"));
String[] nextLine;
while ((nextLine = reader.readNext()) != null) {
// nextLine[] is an array of values from the line
System.out.println(nextLine[0] + nextLine[1] + "etc...");
}
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(this, "The specified file was not found", Toast.LENGTH_SHORT).show();
}
如果要将.csv文件与应用程序打包并在应用程序安装时将其安装在内部存储上,请assets在项目src/main文件夹中创建一个文件夹(例如c:\myapp\app\src\main\assets\),然后将.csv文件放在那里,然后在您的活动中将其引用:
String csvfileString = this.getApplicationInfo().dataDir + File.separatorChar + "csvfile.csv"
File csvfile = new File(csvfileString);
以下代码段从raw资源文件夹中读取一个 CSV 文件（.apk编译时将打包到您的文件中）。
Android 默认不创建raw文件夹。res/raw在您的项目下创建一个原始文件夹并将您的 CSV 文件复制到其中。保持 CSV 文件的名称小写，并在询问时将其转换为文本格式。我的 CSV 文件名是welldata.csv.
在代码片段中，WellData是模型类（带有构造函数、getter 和 setter）并且wellDataList是ArrayList存储数据的 。
private void readData() {
InputStream is = getResources().openRawResource(R.raw.welldata);
BufferedReader reader = new BufferedReader(
new InputStreamReader(is, Charset.forName("UTF-8")));
String line = "";
try {
while ((line = reader.readLine()) != null) {
// Split the line into different tokens (using the comma as a separator).
String[] tokens = line.split(",");
// Read the data and store it in the WellData POJO.
WellData wellData = new WellData();
wellData.setOwner(tokens[0]);
wellData.setApi(tokens[1]);
wellData.setLongitude(tokens[2]);
wellData.setLatitude(tokens[3]);
wellData.setProperty(tokens[4]);
wellData.setWellName(tokens[5]);
wellDataList.add(wellData);
Log.d("MainActivity" ,"Just Created " + wellData);
}
} catch (IOException e1) {
Log.e("MainActivity", "Error" + line, e1);
e1.printStackTrace();
}
}
这在 Kotlin 中对我有用。您需要将 myfile.csv 文件放在 res/raw 文件夹中，如果该文件夹不存在，则创建该文件夹。
val inputStream: InputStream = resources.openRawResource(R.raw.myfile)
val reader = BufferedReader(InputStreamReader(inputStream, Charset.forName("UTF-8")))
reader.readLines().forEach {
//get a string array of all items in this line
val items = it.split(",")
//do what you want with each item
}