嗨,我正在制作一个应用程序,用于使用EditTexts中的用户输入来计算平均值。当我运行该应用程序时,它可以工作,但是当我将该字段保留为空白时,它将引发nullPointerException。我知道它是什么,以及我一般如何修复它们。对于我的代码,我正在考虑使用if语句检查其是否为空。但是我不知道如何用整数检查一个空/空值。有人可以解释一下对此进行检查的最佳方法/做法是什么吗?
欢迎任何提示等!
我的代码:
final Button calculateButton = findViewById(R.id.calculateAverageButton);
calaculateButton.setOnClickListener(new View.onClickListener() {
public void onClick(View v) { TextView averageView = findViewById(R.id.averageView);
int grade[] = {Integer.parseInt(((EditText) findViewById(R.id.grade1)).getText().toString());
int weight[] = {Integer.parseInt(((EditText) findViewById(R.id.weight1)).getText().toString());
int weightTotal = weight[0];
int sum = grade[0] * weight[0];
int average = sum / weightTotal
String averageText = getString(R.string.average);
averageView.setText(averageText + Integer.toString(average));
答案 0 :(得分:1)
这就是为什么您应该避免执行大量内联代码的原因。
没有空整数,您需要检查编辑文本中的字符串
String value = ((EditText) findViewById(R.id.grade1)).getText().toString();
if(value != null && value.length() > 0){
try{
//Since edit text gives you a string you cannot guarantee you have a number input
int numberValue = Integer.parseInt(value);
catch(NumberFormatException e){
//handle exception
}
}
答案 1 :(得分:0)
我建议对此检查editText是否为空:
if(editText.length()>0){
//there is text
}else{
//your code in case of empty editText
}
答案 2 :(得分:0)
首先不要在按钮单击侦听器中启动您的视图(例如:averageView),然后放置以下行:
TextView averageView = findViewById(R.id.averageView);
移出按钮的点击侦听器
字符串具有isEmpty()函数,因此为了在初始化您的成绩[]之前检查空字符串:
EditText grades = ((EditText) findViewById(R.id.grade1));
if (!grades.getText().toString().isEmpty())
do your logic here
else
show some error
答案 3 :(得分:0)
欢迎来到@ J.Doe
关于您的代码有很多要点。
无论如何,我试图快速提及其中的一些并将其修改为如下所示:
final Button calculateButton = findViewById(R.id.calculateAverageButton);
EditText e1 = (EditText) findViewById(R.id.grade1);
EditText e2 = ((EditText) findViewById(R.id.weight1);
TextView averageView = findViewById(R.id.averageView);
calaculateButton.setOnClickListener(new View.onClickListener() {
public void onClick(View v) {
/** better practice for checking NullPointerException **/
if(e1.getText() || e2.getText()){
Log.d(TAG, "Null values");
return;
}
String txt1 = e1.getText().toString();
String tx2 = e2.getText().toString();
boolean emptyE1 = txt1.equals("");
boolean emptyE2 = txt2.equals("");
/** Checking for empty values **/
if(emptyE1 || emptyE2){
Log.d(TAG, "Empty values");
return;
}
int grade;
int weightTotal;
/** You have also to ensure that the strings are numeric**/
try{
grade = new Integer(txt1);
weightTotal = new Integer(txt1);
}
catch(NumberFormatException e){){
Log.d(TAG, "Number input required");
return;
}
/** Now, you are sure you have received numbers :) **/
int sum = grade * weight; // sum ? ;)
int average = sum / weightTotal
String averageText = getString(R.string.average);
averageView.setText(averageText + Integer.toString(average));
}