1

私は次のことをしようとしています：

UserFunctions uf = new UserFunctions();
    JSONArray json = uf.getAllFreebies();
    System.out.println(json + "blah1"); //Here im able to retrieve the whole JSONArray.

try{    
System.out.println("1");
    for (int i = 1; i <json.length(); i++) {
        System.out.println("2");
            jo = json.optJSONObject(i); //Im getting null value here
            System.out.println(jo + "blah2"); //Here im getting null

...}

次の行を使用してJSONArrayを印刷しています。

JSONArray json = uf.getAllFreebies();
System.out.println(json + "blah1");

次の行で、JSONArrayからJSONObjectを取得して出力しようとすると、特定のインデックスでJSONObjectの代わりに「null」が出力されます。

jo = json.optJSONObject(i);
System.out.println(jo + "blah2");

誰かplsは私が間違っていることを教えてもらえますか？つまり、JSONArrayがnullでないときにJSONOBjectのnullを取得するにはどうすればよいですか？

ありがとうございました。

以下は私のJSONArraylogcatです。

05-31 21:02:57.156: I/System.out(318): [["viking","Art","Potrait","Potrait","Good","im giving out potrait 7325697","176 Fiat Ave","Iselin","New Jersey","USA","08830","2012-05-27"],["n00b","Books","Novels","Novels","Good","Im giving out novels 7325697","b9 maa krupa","petlad","Gujarat","India","388450","2012-05-27"],["n00b","Computers","laptop","laptop giveaway","Good","Im giving out laptop if you are interested than pls call on 7325697","B9 Ma  Krupa","Petlad","Gujarat","India","388450","2012-05-27"],["mista","Cameras & Photos","Camera","Camera GiveAway","Very good","im giving out camera .its kodak .pls email me on mista@gmail.com","Mista Lee elm street","seoul","Korea","South Korea","ha8 9sd","2012-05-27"],["panda","Gaming Consoles","XBOX","XBOX 360","Very Good","Im giving out xbox 360.if you are interested please email me on panda@gmail.com","435 Carmen Rd,","Buffalo","New York","USA","14226","2012-05-27"],["viking","Cameras & Photos","Camera","Kodak Camera","Good","Kodak Camera giveaway.Pls call on 732397","","Iselin","New Jersey","USA","08830","2012-05-28"],["viking","Books","Novels","Novel GA","Good","Novel give away.call on 7325697.","","Iselin","New Jersey","USA","08830","2012-05-28"],["viking","Automotive","Car","Car GiveAway","Good","Im giving out car.if you are interested pls call 7323697.","176 Fiat Ave","Iselin","New Jersey","USA","08830","2012-05-29"],["viking","Collectibles","Medallions","Medallion GA","Very Good","Im giving out medallion.if inetrested pls call 732697","176 Fiat Ave,","Iselin","New Jersey","USA","08830","2012-05-29"],["viking","Clothing & Accessories","cloths","cloths giveaway","Good","im giving out cloths if you are interested pls call on 735697","176 Fiat Ave,","Iselin","New jersey","USA","08830","2012-05-29"],["viking","Books","Novel","Novel GA","Good","pls call 735697","435 carmen rd","buffalo","ny","usa","14226","2012-05-29"],["viking","Books","TextBook","CHemistry 101","GOod","pls call 735697","176 fiat ave","iselin","new jersey","usa","08830","2012-05-29"],["mista","Books","Notebook","Notbook","Good","im giving out notebbok if you are interested pls call 48374288423","elm street","seaoul","na","South Korea","jfjafjk","2012-05-29"]]blah1

インデックスiでJSONOBjectを印刷しようとしたときのlogcat出力

05-31 21:02:57.156: I/System.out(318): nullblah2
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1 に答える 1

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JSON[[...], [...], [...]]にはJSONオブジェクトは含まれていませんが、いくつかのJSON配列があります。

したがってoptJSONObject、JSON配列（JSONオブジェクトを予期していた場所）を見つけて、nullタイプが正しくないために戻ります。（オプションoptの略です。）

使用します（オブジェクトではなく配列optJSONArrayに注意してください）。または、を使用します。これにより、失敗時にJSONExceptionがスローされます。getJSONArray

ハッピーコーディング。

JSONは、オブジェクト、配列、およびさまざまな値を厳密に区別していることに注意してください。配列が（JSONの意味で）特別な（サブ）種類のオブジェクトであるという概念はJavaScriptに存在しますが、必ずしも他のJSON実装に拡張されるわけではありません。たとえば、JSONArrayクラスはJSONObjectクラスとは関係がありません。

于 2012-05-31T18:27:22.770 に答える