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我有一个包含 Recycler 视图的 Activity，并使用额外的字符串从主 Activity 调用。然后用户会做一些改变字符串的事情，我想把它发送回主活动。有没有办法只使用手机上的后退按钮来做到这一点？我有结果意图在我的第二个活动的“onPause”方法中设置结果，但主要活动一直说结果被取消。请帮忙！

主要活动代码：


    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(requestCode == 1){
            if(resultCode == RESULT_OK){
                pantryJson = data.getStringExtra("newPantryContents");
                pantry = new ArrayList<>(Arrays.asList(new Gson().fromJson(pantryJson,
                        Ingredient[].class)));
                System.out.println("onActivityResult says: " + pantryJson);
                savePantry();
            }
            if(resultCode == RESULT_CANCELED){
                System.out.println("onActivityResult says: result canceled");
                return;
            }
        }
    }

我的第二个活动：

@Override
    protected void onDestroy() {
        super.onDestroy();

        String pantryJsonArray = new Gson().toJson(pantry);
        System.out.println("ViewPantry onDestroy says: " + pantryJsonArray);
        Intent intent = new Intent(ViewPantryActivity.this,MainActivity.class);
        intent.putExtra("newPantryContents",pantryJsonArray);
        setResult(RESULT_OK,intent);
        finish();
    }

    @Override
    protected void onPause() {
        String pantryJsonArray = new Gson().toJson(pantry);
        System.out.println("ViewPantry onPause Says" + pantryJsonArray);
        Intent resultIntent = new Intent(ViewPantryActivity.this,MainActivity.class);
        resultIntent.putExtra("newPantryContents",pantryJsonArray);
        setResult(ViewPantryActivity.RESULT_OK,resultIntent);
        super.onPause();

    }

LogCat System.Out:

2019-11-02 22:05:42.068 566-566/com.example.myapplication I/System.out: ViewPantry onPause Says[{"barcode":{"cornerPoints":[{"x":181,"y":360},{"x":193,"y":356},{"x":193,"y":479},{"x":181,"y":483}],"displayValue":"04904500","format":1024,"rawValue":"04904500","valueFormat":5},"image":{"mHeight":300,"mNativePtr":497431990208,"mWidth":300},"name":"Clicked","quantityInPantry":1},{"barcode":{"cornerPoints":[{"x":157,"y":359},{"x":229,"y":335},{"x":229,"y":461},{"x":157,"y":487}],"displayValue":"04904500","format":1024,"rawValue":"04904500","valueFormat":5},"image":{"mHeight":300,"mNativePtr":497433345344,"mWidth":300},"name":"Diet Coca-cola","quantityInPantry":3}]
2019-11-02 22:05:42.073 566-566/com.example.myapplication I/System.out: onActivityResult says: result canceled
2019-11-02 22:05:42.516 566-566/com.example.myapplication I/System.out: ViewPantry onDestroy says: [{"barcode":{"cornerPoints":[{"x":181,"y":360},{"x":193,"y":356},{"x":193,"y":479},{"x":181,"y":483}],"displayValue":"04904500","format":1024,"rawValue":"04904500","valueFormat":5},"image":{"mHeight":300,"mNativePtr":497431990208,"mWidth":300},"name":"Clicked","quantityInPantry":1},{"barcode":{"cornerPoints":[{"x":157,"y":359},{"x":229,"y":335},{"x":229,"y":461},{"x":157,"y":487}],"displayValue":"04904500","format":1024,"rawValue":"04904500","valueFormat":5},"image":{"mHeight":300,"mNativePtr":497433345344,"mWidth":300},"name":"Diet Coca-cola","quantityInPantry":3}]
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1 回答 1

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欢迎来到代码派对

首先我必须说你的问题的逻辑：

你想将一些东西传递给一个活动，它只是故意发生的。当您使用 Back btn 回到活动时，您调用此操作的 onResume。

现在解决方案：

  1. 你可以用一个意图覆盖 onBackedPressed，这样你就可以在 onResult 中接收你想要的东西......

2.您可以将代码的位置从 onResult 更改为 onResume。

您可以使用下面的链接了解更多关于 android 中的 lifeCycles

安卓中的生命周期

在评论中更新我

于 2019-11-03T05:40:26.153 回答