Question

我正在研究android csv文件读取库。我在库中创建一个函数并在其他项目中调用它。库函数读取csv文件（位于我的项目的assets文件夹中，从库类扩展），分别将名称和值存储在字符串GotDbname和GotDbValue中。但它没有返回任何东西。任何类型的帮助将不胜感激。

public class ReadFile extends Activity {
String GetDbName = "DBName";
String GetDbVersion = "DbVersion";
String GotDbName;
String GotDbVersion;
HashMap<String, String> DatabaseMap = new HashMap<String, String>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
}

public void hello() {
    Log.d("Library Is working ", "Hello  ");

}

public HashMap<String, String> read(Context con, String name, String version) {
    Log.d("Read File", "Getting Assest Manager");

    AssetManager assetManager = con.getAssets();
    Log.d("Read File", "Assest Manager Object Created");
    if (assetManager == null) {
        Log.d("Reading file", "Nothing in assets");
    }
    else {
        InputStream inputStream = null;
        Log.d("Read File", "Getting input Stream");
        try {
            Log.d("Read File", "Getting File");
            inputStream = assetManager.open("Db.csv");
            Log.d("Read File", "File read");
            String text = loadTextFile(inputStream);

            String[] text1 = text.split(",");

            Log.d("Read File", "LoadTextFile" + text + " " + text1);

            String id[] = new String[text1.length];
            String value[] = new String[text1.length];
            Log.d("Read File", "Getting Strings" + "DbName " + id
                    + "DbVersion  " + value);
            int c = 0;
            for (int i = 0; i < text1.length; i += 2)
            {
                id[c] = text1[i].replace('"', ' ');
                Log.d("Read File", "Getting Db name" + "  " + id[c]);
                c++;
            }
            int d = 0;
            for (int i = 1; i < text1.length; i += 2)
            {
                value[d] = text1[i].replace('"', ' ');
                Log.d("Read File", "Getting getting Version" + "  "
                        + value[d]);
                d++;
            }
            int indexofid = -1;
            for (int i = 0; i < id.length; i++) {
                Log.d("Reading CSV", "In for Loop");
                if (GetDbName.equals(id[i].trim())) {
                    indexofid = i;

                    GotDbName = value[indexofid].toString();
                    Log.d("Read File final", "Getting Db Name" + "  "
                            + GotDbName);
                    break;

                }
            }
            for (int i = 0; i < id.length; i++) {

                if (GetDbVersion.equals(id[i].trim())) {
                    indexofid = i;

                    GotDbVersion = value[indexofid].toString();
                    Log.d("Read File final", "Getting Db Version" + "  "
                            + GotDbVersion);
                    break;

                }

            }
        } catch (IOException e) {
            Log.d("Read File", "No file found");
        }

    }
    DatabaseMap.put(name, GotDbName);
    DatabaseMap.put(version, GotDbVersion);
    Log.d("Read File", " Database Name =" + GotDbName
            + "Database Version =" + GotDbVersion);
    return DatabaseMap;

}

    public String loadTextFile(InputStream inputStream) throws IOException {
    ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
    byte[] bytes = new byte[4096];
    int len = 0;
    while ((len = inputStream.read(bytes)) > 0)
        byteStream.write(bytes, 0, len);
    return new String(byteStream.toByteArray(), "UTF8");
}
}

这是使用该库的其他项目的类

public class MainClass extends ReadFile {
String DbName;
String DbVersion;
String a, b;
TextView txt_dbName, txt_version;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    txt_dbName = (TextView) findViewById(R.id.txt_dbName);
    txt_version = (TextView) findViewById(R.id.txt_version);
    HashMap<String, String> map = new HashMap<>();
    map = read(this, DbName, DbVersion);
    String abc = map.get("name");
    Log.d("Main Class", "Map =" + abc);

    Log.d("MainClass", "DbName = " + DbName + ": DbVersion = "
            + DbVersion);

    txt_dbName.setText(DbName);
    txt_version.setText(DbVersion);
}
}

Answer 1

String DbName;
String DbVersion;
...
map = read(this, DbName, DbVersion);

//The DbName and DbVersion is null or empty?

public HashMap<String, String> read(Context con, String name, String version) {

    ...
    DatabaseMap.put(name, GotDbName);   // If name is null, how to get?
    DatabaseMap.put("name", GotDbName); // Maybe 
    DatabaseMap.put(version, GotDbVersion);
    Log.d("Read File", " Database Name =" + GotDbName
            + "Database Version =" + GotDbVersion);
    return DatabaseMap;
}

HashMap函数返回null值

1 个答案: