java =新Bean(resultset.getString(1)，resultset.getString(2)，resultset.getString

Question

Bean list = new (resultset.getString(1)，resultset.getString(2)，resultset.getString

照上面这样做，我无法得到我想要的结果。有办法把这两个值相加吗？如有任何答案，我们将不胜感激。

while(resultSet.next()){
            if (i < sum.size()) {
                Bean l = sum.get(i);
                String a = l.getSum();
                String b = resultSet.getString(2);
                int ab = Integer.parseInt(a)+Integer.parseInt(b);
            RetBean list = new RetBean(resultSet.getString(1),
                    resultSet.getString(2),l.getSum(),ab);

在这里，我的错误java.lang.NumberFormatException.forInputString(Unknown :输入字符串："728.57“在javax.servlet.http.HttpServlet.service(HttpServlet.java:621) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at java.lang.Integer.parseInt) at java.lang.Integer.parseInt(未知来源) at java.lang.Integer.parseInt(未知来源) at pms.Test.doGet(Test.java:57).apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java：org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(( org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)在java.lang.Thread.run(未知源)

Answer 1

这里有很多猜测，但是如果你想把字符串中包含的两个整数相加，你可以这样做。

 int sum = Integer.parseInt(firstString) + Integer.parseInt(secondString);

对于十进制数，您可以这样做

 BigDecimal sum = BigDecimal.valueOf(firstString)
    .add(BigDecimal.valueOf(secondString));

如果数据库中有数字，则不应该使用getString，还有getInt、getDouble、getBigDecimal。