Android开发：MainMenu编辑按钮无法跳转至MainActivity的问题咨询

在MainActivity录入身高、体重、年龄并选择性别后，应用会跳转至MainMenu页面。现在想在MainMenu中添加「编辑」按钮，点击后返回MainActivity修改已录入的信息，但点击按钮后跳转无效果。已创建id为btnEdit的按钮，设置onClick为btnEditClick，并编写了跳转至MainActivity的Intent逻辑，但没有作用。

MainActivity 代码 #

public class MainActivity extends AppCompatActivity {
    EditText enterHeight, enterWeight, enterAge;

    private double height;
    private double weight;
    private double age;
    String selectedRadiobut;
    Button button;
    RadioButton radioMale, radioFemale;
    RadioGroup radioGroup;
    SharedPreferences sp;

    private boolean heightIsValid() {

        if (enterHeight.getText().toString().length() == 0) {
            enterHeight.setError("Cant be empty");
            return false;
        }

        double height = Double.valueOf(enterHeight.getText().toString());

        if (height <= 0) {

            enterHeight.setError("Cant be zero");
            return false;
        }
        if (height <= 40 || height > 250) {

            enterHeight.setError("Cant be less than 40 cm or more than 250 cm");
            return false;
        }
        return true;
    }

    private boolean weightIsValid() {
        if (enterWeight.getText().toString().length() == 0) {
            enterWeight.setError("Cant be empty");
            return false;
        }

        double weight = Double.valueOf(enterWeight.getText().toString());

        if (weight <= 0) {

            enterWeight.setError("Cant be zero");
            return false;
        }
        if (weight > 600) {

            enterWeight.setError("Cant be more than 600 kg");
            return false;
        }
        return true;
    }

    private boolean ageIsValid() {
        if (enterAge.getText().toString().length() == 0) {
            enterAge.setError("Cant be empty");
            return false;
        }

        double age = Double.valueOf(enterAge.getText().toString());

        if (age <= 0) {

            enterAge.setError("Cant be zero");
            return false;
        }
        if (age > 116) {

            enterAge.setError("Cant be older than 116 years");
            return false;
        }
        return true;
    }

    private boolean genderIsSelected() {

        if (radioGroup.getCheckedRadioButtonId() == -1) { //checking if the user has selected a option using id
            Toast toast = Toast.makeText(this, "Please select gender", Toast.LENGTH_SHORT);
            toast.show();
            return false;
        }
        if (radioMale.isChecked()) {
            selectedRadiobut = radioMale.getText().toString();
        } else if (radioFemale.isChecked()) {
            selectedRadiobut = radioFemale.getText().toString();
        }
        return true;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getSupportActionBar().hide();
        setContentView(R.layout.activity_main);
        getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
        sp = getSharedPreferences("MyUserPrefs", Context.MODE_PRIVATE);

        if (sp.contains("height") && sp.contains("weight") && sp.contains("age") && sp.contains("gender")) {
            // Values are stored, navigate to MainMenu directly
            Intent intent = new Intent(MainActivity.this, MainMenu.class);
            startActivity(intent);
        } else {
            radioMale = (RadioButton) findViewById(R.id.radioMale);
            radioFemale = (RadioButton) findViewById(R.id.radioFemale);
            button = (Button) findViewById(R.id.button);
            enterHeight = (EditText) findViewById(R.id.enterHeight);
            enterWeight = (EditText) findViewById(R.id.enterWeight);
            enterAge = (EditText) findViewById(R.id.enterAge);
            radioGroup = (RadioGroup) findViewById(R.id.radioSex);

            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {


                    if (heightIsValid() & weightIsValid() & ageIsValid() & genderIsSelected()) {

                        height = Double.valueOf(enterHeight.getText().toString());
                        weight = Double.valueOf(enterWeight.getText().toString());
                        age = Double.valueOf(enterAge.getText().toString());

                        SharedPreferences.Editor editor = sp.edit();
                        editor.putString("height", String.valueOf(Integer.valueOf((int) height)));
                        editor.putString("weight", String.valueOf(Integer.valueOf((int) weight)));
                        editor.putString("age", String.valueOf(Integer.valueOf((int) age)));
                        editor.putString("gender", String.valueOf(selectedRadiobut));
                        editor.commit();

                        InputMethodManager imm = (InputMethodManager) getSystemService(getApplicationContext().INPUT_METHOD_SERVICE);
                        imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
                        Intent intent = new Intent(MainActivity.this, MainMenu.class);
                        startActivity(intent);
                    }
                }
            });
        }
    }
    @Override
    protected void onResume() {
        super.onResume();
        if (enterHeight != null) {
            enterHeight.setText("");
        }
        if (enterWeight != null) {
            enterWeight.setText("");
        }
        if (enterAge != null) {
            enterAge.setText("");
        }
        if (radioGroup != null) {
            radioGroup.clearCheck();
        }
    }
}

MainMenu 代码 #

public class MainMenu extends AppCompatActivity { Button  btnMC , btnFN , btnRec , btnGuides, btnEdit;
    public void btnStepClick(View view) {
        Intent intent = new Intent(this, StepCounter.class);
        startActivity(intent);
    }
    public void btnCalClick(View view) {
        Intent intent = new Intent(this, MacrosCalculator.class);
        startActivity(intent);
    }
    public void btnRecClick(View view){
        Intent intent = new Intent(this, Recipes.class);
        startActivity(intent);
    }
    public void btnEditClick(View view){
        Log.d("MainMenu", "Edit button clicked");
        Intent intent = new Intent(this, MainActivity.class);
        startActivity(intent);
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getSupportActionBar().hide();
        setContentView(R.layout.activity_main_menu);
        TextView age1 , height1 , weight1 , gender1;

        age1 = (TextView) findViewById(R.id.age1);
        height1 = (TextView) findViewById(R.id.height1);
        weight1 = (TextView) findViewById(R.id.weight1);
        gender1 = (TextView) findViewById(R.id.gender1);
        btnMC = (Button) findViewById(R.id.btnMC);
        btnFN = (Button) findViewById(R.id.btnFN);
        btnRec = (Button) findViewById(R.id.btnRec);
        btnGuides = (Button) findViewById(R.id.btnGuides);
        btnEdit = (Button) findViewById(R.id.btnEdit);

        SharedPreferences sp = getApplicationContext().getSharedPreferences("MyUserPrefs", Context.MODE_PRIVATE);
        String height = sp.getString("height" , "");
        String weight = sp.getString("weight" , "");
        String age = sp.getString("age" , "");
        String gender= sp.getString("gender", "");

        gender1.setText("Gender: " + gender);
        age1.setText("Age: " + age);
        height1.setText("Height(cm): " + height);
        weight1.setText("Weight(kg): " + weight);
    }
}

问题根源 #

点击编辑按钮后，虽然Intent触发了跳转，但MainActivity的onCreate方法会检查SharedPreferences中是否存在用户数据，由于之前已经录入过信息，这一条件成立，代码会立即再次跳回MainMenu，导致用户看不到MainActivity的界面。

解决步骤 #

1. 修改MainMenu的跳转逻辑：在跳转到MainActivity时，添加编辑模式标记：

public void btnEditClick(View view){
    Log.d("MainMenu", "Edit button clicked");
    Intent intent = new Intent(this, MainActivity.class);
    intent.putExtra("IS_EDIT_MODE", true); // 添加编辑模式标记
    startActivity(intent);
}

2. 修改MainActivity的onCreate逻辑：读取标记，编辑模式下跳过自动跳转，同时填充已有数据：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getSupportActionBar().hide();
    setContentView(R.layout.activity_main);
    getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
    sp = getSharedPreferences("MyUserPrefs", Context.MODE_PRIVATE);

    // 读取编辑模式标记
    boolean isEditMode = getIntent().getBooleanExtra("IS_EDIT_MODE", false);

    if (!isEditMode && sp.contains("height") && sp.contains("weight") && sp.contains("age") && sp.contains("gender")) {
        // 非编辑模式且有数据时，才跳转到MainMenu
        Intent intent = new Intent(MainActivity.this, MainMenu.class);
        startActivity(intent);
        finish(); // 结束当前Activity，避免返回栈问题
    } else {
        // 初始化控件
        radioMale = (RadioButton) findViewById(R.id.radioMale);
        radioFemale = (RadioButton) findViewById(R.id.radioFemale);
        button = (Button) findViewById(R.id.button);
        enterHeight = (EditText) findViewById(R.id.enterHeight);
        enterWeight = (EditText) findViewById(R.id.enterWeight);
        enterAge = (EditText) findViewById(R.id.enterAge);
        radioGroup = (RadioGroup) findViewById(R.id.radioSex);

        // 编辑模式下填充已有数据
        if (isEditMode) {
            String height = sp.getString("height", "");
            String weight = sp.getString("weight", "");
            String age = sp.getString("age", "");
            String gender = sp.getString("gender", "");

            enterHeight.setText(height);
            enterWeight.setText(weight);
            enterAge.setText(age);
            if (gender.equals(radioMale.getText().toString())) {
                radioMale.setChecked(true);
            } else if (gender.equals(radioFemale.getText().toString())) {
                radioFemale.setChecked(true);
            }
        }

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (heightIsValid() & weightIsValid() & ageIsValid() & genderIsSelected()) {
                    height = Double.valueOf(enterHeight.getText().toString());
                    weight = Double.valueOf(enterWeight.getText().toString());
                    age = Double.valueOf(enterAge.getText().toString());

                    SharedPreferences.Editor editor = sp.edit();
                    editor.putString("height", String.valueOf(Integer.valueOf((int) height)));
                    editor.putString("weight", String.valueOf(Integer.valueOf((int) weight)));
                    editor.putString("age", String.valueOf(Integer.valueOf((int) age)));
                    editor.putString("gender", String.valueOf(selectedRadiobut));
                    editor.commit();

                    InputMethodManager imm = (InputMethodManager) getSystemService(getApplicationContext().INPUT_METHOD_SERVICE);
                    imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
                    Intent intent = new Intent(MainActivity.this, MainMenu.class);
                    startActivity(intent);
                    finish(); // 结束当前Activity
                }
            }
        });
    }
}

3. 修改MainActivity的onResume方法：编辑模式下不清空输入框：

@Override
protected void onResume() {
    super.onResume();
    boolean isEditMode = getIntent().getBooleanExtra("IS_EDIT_MODE", false);
    if (!isEditMode) {
        if (enterHeight != null) {
            enterHeight.setText("");
        }
        if (enterWeight != null) {
            enterWeight.setText("");
        }
        if (enterAge != null) {
            enterAge.setText("");
        }
        if (radioGroup != null) {
            radioGroup.clearCheck();
        }
    }
}

内容的提问来源于stack exchange，提问作者VGoychev