Question

我正在创建一个验证登录字段（用户名和密码）的方法。我创建了一个方法并在click事件上调用它，但它无法正常工作。

package com.boyzcorn.android.fyp;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

/** Called when the activity is first created. */
public class login extends Activity {
    EditText eText = (EditText)findViewById(R.id.uid);
    EditText eText2 = (EditText)findViewById(R.id.editText2);
    Button btnSubmit = (Button)findViewById(R.id.sbtn);
    Button btnSignup = (Button)findViewById(R.id.signupbtn);

    /* I think there is some problem with my method definition but i am not
       getting it. */

    public void validation(EditText username,EditText pass) {
        if (username.getText().toString().equals("") ||
                pass.getText().toString().equals("")) {
            Toast.makeText(
                    getApplicationContext(),
                    "Fill Empty Fields",Toast.LENGTH_SHORT
                ).show();
        } else {
            Intent i = new Intent(login.this,order_pushing.class);
            startActivity(i);
        }
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);

        btnSubmit.setOnClickListener(new OnClickListener() {
            public void onClick(View v) { 
                validation(eText,eText2);
            }
        });

        btnSignup.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                Intent i = new Intent(login.this,signup.class);
                startActivity(i);
            }
        });

    }
}

Answer 1

将此代码放在活动{

下

EditText eText;
EditText eText2;
Button btnSubmit;
Button btnSignup;

并在 setContentView（R.layout.login）;

之后在OnCreate中初始化它

eText = (EditText)findViewById(R.id.uid);
eText2 = (EditText)findViewById(R.id.editText2);
btnSubmit = (Button)findViewById(R.id.sbtn);
btnSignup = (Button)findViewById(R.id.signupbtn);

希望这会起作用

Answer 2

您在设置内容视图之前定义了按钮。在onCreate()之后将以下行移至setContentView(R.layout.login)：

EditText eText = (EditText)findViewById(R.id.uid);
EditText eText2 = (EditText)findViewById(R.id.editText2);
Button btnSubmit = (Button)findViewById(R.id.sbtn);
Button btnSignup = (Button)findViewById(R.id.signupbtn);

永远不会调用定义的方法

2 个答案: