Question

我想向InformationActivity发送2个不同的值。
首先：我想发送条形码编号和列表（工作正常）。但由于某种原因，我发送的列表（小麦或小吃或鸡蛋取决于我按下的内容）没有出现在InformationActivity中。
我认为问题是因为它分为两个不同的类。

如何更改代码，以便将条形码字符串和其中一个列表发送到下一个活动中？

PS。我尝试将intent声明为全局变量并且崩溃了应用程序 PSS。目前我只是通过在该阵列中打印i项来测试它。

主：

public class HomeActivity extends AppCompatActivity{

private FirebaseAuth firebaseAuth;
private Button buttonLogout;
private ZXingScannerView scannerView;
private final int permission_code = 1;

Spinner spinner;
ArrayAdapter<CharSequence> adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);

    firebaseAuth = FirebaseAuth.getInstance();
    if(firebaseAuth.getCurrentUser() == null){
        finish();
        startActivity(new Intent(this, MainActivity.class));
    }
    FirebaseUser user = firebaseAuth.getCurrentUser();

    //android spinner to select profile
    spinner = (Spinner)findViewById(R.id.spinnerProfiles);
    adapter = ArrayAdapter.createFromResource(this, R.array.restrictions, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_list_item_1);
    spinner.setAdapter(adapter);
    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            String item = parent.getItemAtPosition(position).toString();
            Toast.makeText(getBaseContext(), item + " Selected", Toast.LENGTH_SHORT).show();
            Intent intent = new Intent(getApplicationContext(), InformationActivity.class);
            switch (position){
                case 0:
                    String[] wheat = getResources().getStringArray(R.array.Wheat);
                    intent.putExtra("Profile", wheat);
                    break;
                case 1:
                    String[] crus = getResources().getStringArray(R.array.Crustaceans);
                    intent.putExtra("Profile", crus);
                    break;
                case 2:
                    String[] eggs = getResources().getStringArray(R.array.Eggs);
                    intent.putExtra("Profile", eggs);
                    break;
            }
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
            return;
        }
    });

}


//opens camera when button is pressed
public void scanBarcode(View view) {
    //check if user given app camera permissions
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, permission_code);

    }
    //opens camera
    scannerView = new ZXingScannerView(this);
    scannerView.setResultHandler(new ZXingScannerResultHandler());
    //stops camera and scannerview
    setContentView(scannerView);
    scannerView.startCamera();

}

//stops camera and outputs barcode result to a Toast
class ZXingScannerResultHandler implements ZXingScannerView.ResultHandler {
    @Override
    public void handleResult(Result result) {
        String resultBarcode = result.getText();
        Intent intent = new Intent(getApplicationContext(), InformationActivity.class);
        intent.putExtra("barcode", resultBarcode.toString());
        startActivity(intent);
        scannerView.stopCamera();
    }
}

InformationActivity：

public class InformationActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_information);

    TextView barcodeView = (TextView) findViewById(R.id.tvBarcode);
    barcodeView.setText(getIntent().getExtras().getString("barcode"));

    TextView profileView = (TextView) findViewById(R.id.tvProfile);
    String[] Profile = getIntent().getStringArrayExtra("Profile");
    profileView.setText(Profile[1]);


}


@Override
public void onBackPressed() {
    Intent intent = new Intent(getApplicationContext(), HomeActivity.class);
    startActivity(intent);
}
}

Answer 1

您的import pandas as pd df = pd.read_csv('kmeans.csv', header=None) df.plot(kind='scatter', x=0, y=1, c=2, colormap='rainbow', colorbar=None, markeredgewidth=0.0) # No circle margin!方法正在向onItemSelected()对象添加String[]，但之后只会抛出Intent。

Intent

稍后，您使用不同 @Override public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { ... Intent intent = new Intent(getApplicationContext(), InformationActivity.class); switch (position){ case 0: String[] wheat = getResources().getStringArray(R.array.Wheat); intent.putExtra("Profile", wheat); break; case 1: String[] crus = getResources().getStringArray(R.array.Crustaceans); intent.putExtra("Profile", crus); break; case 2: String[] eggs = getResources().getStringArray(R.array.Eggs); intent.putExtra("Profile", eggs); break; } }启动活动：

Intent

重要的是要理解这两个意图不以某种方式共享;第一个与第二个完全分开，只要@Override public void handleResult(Result result) { String resultBarcode = result.getText(); Intent intent = new Intent(getApplicationContext(), InformationActivity.class); intent.putExtra("barcode", resultBarcode.toString()); startActivity(intent); scannerView.stopCamera(); }完成执行，意图就会被抛弃。

您应该做的是更改onItemSelected()方法，以便以某种方式存储有关选择的信息（可能更新活动中的变量），然后更改onItemSelected()方法以读取保存的信息并将数组添加到intent。也许是这样的：

handleResult()

String[] selectedArray;

@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
    ...
    switch (position){
        case 0:
            selectedArray = getResources().getStringArray(R.array.Wheat);
            break;
        case 1:
            selectedArray = getResources().getStringArray(R.array.Crustaceans);
            break;
        case 2:
            selectedArray = getResources().getStringArray(R.array.Eggs);
            break;
    }
}

Answer 2

我认为您应该使用startActivityForResult()来更好地管理您的活动之间的信息交换，并构建一个更加可靠的应用。

Answer 3

你需要调用scanBarcode（）函数来激活意图并使用Ben提供的完美解决方案启动InformationActivity：

String[] selectedArray;
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
    ...
    switch (position){
        case 0:
            selectedArray = getResources().getStringArray(R.array.name);
            break;
        case 1:
            selectedArray = getResources().getStringArray(R.array.name);
            break;
    }
}

也简单地调用finish（）;函数在InformationActivity的onBackPressed（）中导航到Mainactivity：

    @Override
public void onBackPressed() {
    super.finish(); // or use super.onBackPressed(); 
}

快乐编码：）

意图在不同的类/方法之间

3 个答案: