java - 使用复选框允许用户保存 TextView 和编辑 View 中的值，以便在重新打开应用程序时立即看到它们。

Question

对 android java 编程非常陌生。我为我的一个类(class)创建了一个汽车支付计算器应用程序，我试图创建一个用户可以选中的复选框，以便在再次打开应用程序时，存储在 TextView 和 EditView 中的所有值保持不变。

这是我的 Activity :

public class MainActivity extends Activity implements OnClickListener,
    OnEditorActionListener, OnItemSelectedListener, OnFocusChangeListener,
    OnCheckedChangeListener {
private TextView payment;
private TextView interest;
private EditText principle;
private TextView interestText;
private CheckBox interestBox;
private EditText years;
private TextView apr;
Button plusbutton;
Button minusbutton;
private static String TAG = "CAR";
private Spinner period;
private double aprPercent;
private int t;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Log.d(TAG, "onCreate");
    this.getReferences();
    this.setListeners();    
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

public void getReferences() {
    payment = (TextView) findViewById(R.id.paymentLabel);
    interest = (TextView) findViewById(R.id.interestLabel);
    apr = (TextView) findViewById(R.id.aprLabel);
    aprPercent = Double.parseDouble(apr.getText().toString());
    interestText = (TextView) findViewById(R.id.interestText);
    interestBox = (CheckBox) findViewById(R.id.checkBox1);
    interestBox.setChecked(false);
    principle = (EditText) findViewById(R.id.principleEditText);
    years = (EditText) findViewById(R.id.yearsEditText);
    period = (Spinner) findViewById(R.id.spinner1);
    minusbutton = (Button) findViewById(R.id.minusbutton);
    plusbutton = (Button) findViewById(R.id.plusbutton);
    ArrayAdapter<CharSequence> adapter = ArrayAdapter
            .createFromResource(this, R.array.split_array,
                    android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    period.setAdapter(adapter);


    // principle.setOnFocusChangeListener(this);
    Log.d(TAG, "getReferences principle: " + principle.getText()
            + " years:" + years.getText());

}

public void setListeners() { // where the event being consumed will be
                                // responding
    principle.setOnFocusChangeListener(this);
    principle.setOnEditorActionListener(this);
    years.setOnFocusChangeListener(this);
    years.setOnEditorActionListener(this);
    interestBox.setOnCheckedChangeListener(this);
    period.setOnItemSelectedListener(this);

    Log.d(TAG, "setListeners principle: " + principle.getText() + " years:"
            + years.getText());
}

public void setPeriodValue() {
    if (period.getSelectedItem().toString().equalsIgnoreCase("Monthly")) {
        t = 12;
    } else if (period.getSelectedItem().toString()
            .equalsIgnoreCase("Quarterly")) {
        t = 4;
    } else if (period.getSelectedItem().toString()
            .equalsIgnoreCase("Annually")) {
        t = 1;
    }
}

public void updateResults() {
    double dblPrinciple = Double
            .parseDouble(principle.getText().toString());
    double dblYears = Double.parseDouble(years.getText().toString());

    double num, denom, dblPayment;
    double r = aprPercent / 100;
    NumberFormat nf = NumberFormat.getNumberInstance();
    NumberFormat curr = NumberFormat.getCurrencyInstance();
    apr.setText(nf.format(aprPercent));
    setPeriodValue();
    num = (r / t);
    denom = (1 - Math.pow((1 + num), (t * -dblYears)));
    dblPayment = dblPrinciple * (num / denom);
    payment.setText(curr.format(dblPayment));
    interest.setText(curr
            .format((dblPayment * t * dblYears) - dblPrinciple));

}

public void onFocusChange(View v, boolean hasfocus) {
    Log.d(TAG, "Focus Change principle: " + principle.getText() + " years"
            + years.getText());
    switch (v.getId()) {
    case R.id.principleEditText:
    case R.id.yearsEditText:
        updateResults();
    default:
        updateResults();

    }
}

@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
    if(interestBox.isChecked()) {
        interest.setVisibility(View.VISIBLE);
        interestText.setVisibility(View.VISIBLE);
    }
    else {
        interest.setVisibility(View.INVISIBLE);
        interestText.setVisibility(View.INVISIBLE);
    }
    if (interestBox.isChecked()!=true){
        interest.setVisibility(View.INVISIBLE);
        interestText.setVisibility(View.INVISIBLE);
    }
    else {
        interest.setVisibility(View.VISIBLE);
        interestText.setVisibility(View.VISIBLE);
    }       
}

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

@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
    updateResults();
    return false;
}

@Override
public void onClick(View v) {
    switch (v.getId()) {
    case R.id.minusbutton:
        if (aprPercent == 1) {
            break;
        } else {
            aprPercent = aprPercent - 1.0;
            updateResults();
            break;
        }
    case R.id.plusbutton:
        if (aprPercent == 20) {
            break;
        } else {
            aprPercent = aprPercent + 1.0;
            updateResults();
            break;
        }
    }
}

@Override
public void onItemSelected(AdapterView<?> parent, View view, int position,
        long id) {
    updateResults();
}

我的猜测是我必须对共享首选项做一些事情，但我不太确定如何去做。任何朝正确方向的插入都会很棒。谢谢。

Answer 1

使用getSharedPreferences(...).edit().putString(...).commit()将值存储在“onPause()”中，然后再次使用getSharedPreferences(。 ..).getString(...) 检索“onResume()”中的信息。就是这么简单。