java Try catch不起作用（总是执行catch代码）

Question

如果有人能帮助我，我将不胜感激！应该将三个EditText变量转换为字符串，然后再转换为整数。我添加了异常，因为没有它，程序在启动时崩溃。我不确定问题是在变量转换、try-catch代码中，还是两者都有。请帮忙

package boston.project;

import 安卓.app.Activity;
import 安卓.os.Bundle;
import 安卓.view.View;
import 安卓.widget.Button;
import 安卓.widget.EditText;
import 安卓.widget.TextView;



public class TheBostonProjectActivity extends Activity {

public EditText aed, bed, ced;
public TextView dtv;
public int a, b, c;
public Button solve;
public double dis;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);


        aed = (EditText)(findViewById(R.id.etA));
                    try {
                        a = Integer.parseInt(aed.getText().toString());
                        } catch (NumberFormatException e) {
                            a = 0;
                        }
        bed = (EditText)(findViewById(R.id.etB));
                    try {
                        b = Integer.parseInt(bed.getText().toString());
                        } catch (NumberFormatException e) {
                            b = 0;
                        }
        ced = (EditText)(findViewById(R.id.etC));
                    try {
                        c = Integer.parseInt(ced.getText().toString());
                        } catch (NumberFormatException e) {
                            c = 0;
                        }

    solve = (Button)(findViewById(R.id.bsolve));

    solve.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            // Perform action on click
            dis = (b*b)-(4*a*c);
            dtv = (TextView)findViewById(R.id.tvdis);
            dtv.setText("Discriminant:" + dis);
        }
    });

}
}

Answer 1

您正在尝试在创建EditText之后（通过调用setContentView）从EditText获取文本。它们都是空的-不包含文本。自从

Integer.parseInt("");

抛出一个异常，所有的catch块都会被执行（这意味着它们实际上可以工作，而不是相反）