如何根据单击主 Activity 中的按钮时所选微调器选项的文本在另一个 Activity 中设置标题

Question

我着手创建一个包含 3 个活动的 Android 应用程序项目。

第一个 activity 的布局包含 3 个元素、2 个微调器和一个按钮。

我打算让它们按以下方式工作：

MainActivity.java: 1. 假设我希望第一个微调器在应用程序启动时加载一组类别。例如，收入、支出。 2. 在我 select 来自第一个微调器的类别后，第二个微调器将在第二个微调器中加载其各自的 sub-categories。例如，如果我在第一个微调器中选择收入，则第二个微调器会加载佣金、薪水、奖金等，如果选择支出，则在第二个微调器中加载每月支出、运输费用、账单等。 3. 现在，根据我选择的 sub-category，当我单击按钮时，它将打开一个新的 activity 并为该特定类别设置操作栏的标题和 sub-category.例如，如果我选择收入和薪水，那么在我单击主 activity 中的按钮后，下一个 activity 将显示收入、薪水作为标题。

我创建了一个名为 Utils.java 的 class 来将类别集和 sub-category 名称存储为字符串数组。

public class Utils{

    public static String[] mainCategoryList =
    {
        "Choose One",
        "Income",
        "Expenditure"
    };

    //
    public static String[] chooseOne_list=
    {
        "Choose One"
    };

    public static String[] income_subCategoryList =
    {
        "Bonus",
        "Commision",
        "Salary"                 
    };

    public static String[] expenditure_subCategoryList=
    {
         "Bills",
         "Conveyance",
         "Monthly Expenditure"
    };

    public static String[] income=
    {
        "Income, Bonus",
        "Income, Commission",
        "Income, Salary"
    };

    public static String[] expenditure=
    {
        "Expenditure, Bills",
        "Expenditure, Conveyance",
        "Expenditure, Monthly Expenditure"
    };
}

我为MainActivity.java完成的编码如下，

public class MainActivity extends AppCompatActivity {

Spinner spinner1_mainCategory, spinner2_subCategory;
Button buttonChoose;
String spinner1Item, spinner2Item;
Intent intent;


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

    //Spinner element
    spinner1_mainCategory = (Spinner)findViewById(R.id.spinner1_mainCategory);
    spinner2_subCategory = (Spinner)findViewById(R.id.spinner2_subCategory);

    //Button element
    buttonChoose = (Button)findViewById(R.id.buttonChoose);

    //To keep onCreate() clean of multiple adapter setting
    adapterMethod(spinner1_mainCategory,mainCategoryList);

    // Spinner click listener
    spinner1_mainCategory.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int position, long id) {
            //String.valueOf(array_name.getSelectedItem()) captures the value of the selected option of a specific string array onClick event
            spinner1Item = String.valueOf(spinner1_mainCategory.getSelectedItem());


            switch (position){
                case 0:
                    adapterMethod(spinner2_subCategory,chooseOne_list);
                    spinner2_subCategory.setVisibility(View.GONE);
                    //Button click listener
                    buttonChoose.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {

                            if (spinner1Item.contentEquals(Utils.mainCategoryList[0])){
                                Toast toast = Toast.makeText(getApplicationContext(), "Choose a Category First", Toast.LENGTH_SHORT);
                                toast.setGravity(Gravity.CENTER|Gravity.CENTER_HORIZONTAL,0,0);
                                toast.show();
                            }
                        }
                    });
                    break;
                case 1:
                    adapterMethod(spinner2_subCategory,income_subCategoryList);
                    spinner2_subCategory.setVisibility(View.VISIBLE);
                    break;
                case 2:
                    adapterMethod(spinner2_subCategory,expenditure_subCategoryList);
                    spinner2_subCategory.setVisibility(View.VISIBLE);
                    break;
            }
        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {

        }
    });


    spinner2_subCategory.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, final int position, long id) {
            spinner2Item = String.valueOf(spinner2_subCategory.getSelectedItem());

            switch (position){
                case 0:
                    //Income Category, Bonus Sub-category
                    if (spinner2Item.contentEquals(Utils.mainCategoryList[1]) && spinner2Item.contentEquals(income_subCategoryList[0])){
                        buttonChoose.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View view) {
                                changeTitleInNextActivity(Utils.income[0]);
                            }
                        });
                    }
                    //Expenditure Category, Bills Sub-category
                    if (spinner2Item.contentEquals(Utils.mainCategoryList[2]) && spinner2Item.contentEquals(expenditure_subCategoryList[0])){
                        buttonChoose.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View view) {
                                changeTitleInNextActivity(Utils.expenditure[0]);
                            }
                        });
                    }

                    break;
                case 1:
                    //Income Category, Commission Sub-category
                    if (spinner2Item.contentEquals(Utils.mainCategoryList[1]) && spinner2Item.contentEquals(income_subCategoryList[1])){
                        buttonChoose.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View view) {
                                changeTitleInNextActivity(Utils.income[1]);
                            }
                        });
                    }
                    //Expenditure Category, Conveyance Sub-category
                    if (spinner2Item.contentEquals(Utils.mainCategoryList[2]) && spinner2Item.contentEquals(expenditure_subCategoryList[1])){
                    buttonChoose.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {
                            changeTitleInNextActivity(Utils.expenditure[1]);
                        }
                    });
                }

                break;
                case 2:
                    //Income Category, Salary Sub-category
                    if (spinner2Item.contentEquals(Utils.mainCategoryList[1]) && spinner2Item.contentEquals(income_subCategoryList[2])){
                        buttonChoose.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View view) {
                                changeTitleInNextActivity(Utils.income[2]);
                            }
                        });
                    }
                    //Expenditure Category, Monthly Expenditure Sub-category
                    if (spinner2Item.contentEquals(Utils.mainCategoryList[2]) && spinner2Item.contentEquals(expenditure_subCategoryList[2])){
                        buttonChoose.setOnClickListener(new View.OnClickListener() {
                            @Override
                            public void onClick(View view) {
                                changeTitleInNextActivity(Utils.expenditure[2]);
                            }
                        });
                    }
                    break;
            }
        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {

        }
    });
}

public void adapterMethod(View v, String[] list){
    // Creating adapter for spinner
    ArrayAdapter<String> dataAdapter = new ArrayAdapter<>(this,
            android.R.layout.simple_spinner_item, list);
    // Drop down layout style - list view with radio button
    dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    dataAdapter.notifyDataSetChanged();
    // attaching adapter to spinner for district
    if (v.getId()==R.id.spinner1_mainCategory){
        spinner1_mainCategory.setAdapter(dataAdapter);
        spinner1_mainCategory.setSelection(0, false);
    }
    if (v.getId()==R.id.spinner2_subCategory){
        spinner2_subCategory.setAdapter(dataAdapter);
        spinner2_subCategory.setSelection(0, false);
    }
}

public void changeTitleInNextActivity(String title){

    intent = new Intent(getApplicationContext(),SecondActivity.class);
    intent.putExtra("Title", title);
    startActivity(intent);

}

}

SecondActivity.java

public class SecondActivity extends AppCompatActivity {

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

    Intent intent = getIntent();
    String title = intent.getStringExtra("Title");
    getSupportActionBar().setTitle(title);
}

}

我不明白为什么，但我无法让编码按照我想要的方式为我工作。从第一个和第二个微调器中进行的选择工作得很好，但是无论我尝试多少种方法，我都无法在下一个 activity 中设置标题的按钮。

告诉我，伙计们，我做错了什么？如何更好地编写代码来避免这种陷阱。

无法创建按钮 "Choose":

去SecondActivity

Answer 1

在你的第二个 activity，获取您传递的字符串

String title=getIntent().getStringExtra("Title");

然后设置你的标题

getSupportActionBar().setTitle(title);

如何根据单击主 Activity 中的按钮时所选微调器选项的文本在另一个 Activity 中设置标题

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