3
我目前正在使用android的第一步。我正在开发一个非常简单的计算器，其中我有两个活动，一个主要活动和一个结果活动。在这个结果活动中，我有一个返回按钮，这是他主要的活动。问题是，当我回到主要活动时，我在文本字段上的值仍然存在。我该怎么做，以便当我从结果活动返回时，主要活动的字段被清除？Android - 重置不同活动的字段
下面是我的主要活动代码：
public class MainActivity extends Activity implements OnCheckedChangeListener{
private static final int REQUEST_CODE = 1;
private EditText number1, number2;
private Button btn1;
private Intent intent;
private String operation;
private RadioGroup RadioGroupOperation;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//faz a ligação entre a aplicação e o layout
number1 = (EditText)findViewById(R.id.editText1);
number2 = (EditText)findViewById(R.id.editText2);
btn1 = (Button)findViewById(R.id.calcular);
intent = new Intent(this, ResultActivity.class);
btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//insere na intent os dois numeros digitados pelo utilizador
intent.putExtra("number1", number1.getText().toString());
intent.putExtra("number2", number2.getText().toString());
intent.putExtra("operation", operation);
startActivityForResult(intent, REQUEST_CODE);
}
});
RadioGroupOperation = (RadioGroup)findViewById(R.id.radioGroup1);
RadioGroupOperation.setOnCheckedChangeListener(this);
}
@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 void onCheckedChanged(RadioGroup group, int checkedId) {
switch(checkedId){
case R.id.soma:
operation="+";
break;
case R.id.subtracao:
operation="-";
break;
case R.id.multiplicacao:
operation="*";
break;
case R.id.divisao:
operation="/";
break;
}
Toast.makeText(MainActivity.this, operation, Toast.LENGTH_SHORT).show();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data){
if(resultCode == RESULT_OK && requestCode == REQUEST_CODE){
if(data.hasExtra("result")){
Toast.makeText(this, "O resultado da operação anterior foi:" + data.getExtras().getString("result") , Toast.LENGTH_LONG).show();
}
//testing
/*if(data.hasExtra("number1") && data.hasExtra("number2")){
number1.setText(0);
number2.setText(0);
}*/
//end testing
}
}
}
我的第二个活动（结果）：
public class ResultActivity extends Activity {
private TextView textView1;
private Intent intent;
private String number1, number2, operation;
private double result;
private Button btn1;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_result);
btn1 = (Button)findViewById(R.id.voltar);
intent = getIntent();
//armazena os numeros digitados
number1 = intent.getStringExtra("number1");
number2 = intent.getStringExtra("number2");
operation = intent.getStringExtra("operation");
//Efectua calculos
try {
if(operation.equals("+"))
result = (Double.parseDouble(number1) + Double.parseDouble(number2));
else if(operation.equals("-"))
result = (Double.parseDouble(number1) - Double.parseDouble(number2));
else if(operation.equals("*"))
result = (Double.parseDouble(number1) * Double.parseDouble(number2));
else if(operation.equals("/"))
result = (Double.parseDouble(number1)/Double.parseDouble(number2));
textView1 = (TextView)findViewById(R.id.textView1);
textView1.setText("O resultado é " + String.valueOf(result));
btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
finish();
}
});
}
catch(Exception e){
Toast.makeText(this, "Ocorreu um erro!", Toast.LENGTH_SHORT).show();
this.finish();
}
}
@Override
public void finish(){
Intent data = new Intent();
data.putExtra("result", String.valueOf(result));
//testing
//data.putExtra("number1", 0);
//data.putExtra("number2", 0);
//end testing
setResult(RESULT_OK, data);
super.finish();
}
}
我已经尝试过这样做，如果你看到//测试之间的块并且//结束测试，但结果是当我尝试返回到第一个活动时，我崩溃了该应用程序。
有关我如何做到这一点的任何想法？
由于提前， CT
谢谢您的回答，我会尽快，我可以测试它。 –
这个陈述是不正确的 - “当你回来的时候，你在onCreate中做的初始化失败了。” – San