由于文本输入错误，应用程序不断崩溃[重复]

Posted 2023-04-18

【中文标题】由于文本输入错误，应用程序不断崩溃[重复]

【英文标题】：App keeps crashing due to error in text input [duplicate]

【发布时间】：2019-05-02 03:12:56

【问题描述】：

当我在 android studio 中按下按钮启动它时，我的项目合作伙伴的代码不断崩溃。这是我在 logcat 中遇到的错误。 原因：java.lang.NullPointerException：尝试在空对象引用上调用虚拟方法“android.text.Editable android.widget.EditText.getText()”。

这指的是第 21 行，其中：String fullName = name.getText().toString();

帮助？

@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);



    Intent intent = new Intent(MainActivity1.this, SecondActivity.class);

    EditText name = (EditText)findViewById(R.id.entName);
    String fullName = name.getText().toString();
    intent.putExtra("name_key", fullName);

    EditText ages = findViewById(R.id.age);
    String age = ages.getText().toString();
    intent.putExtra("age_key", age);

    RadioGroup gender = findViewById(R.id.genRGroup);
    int genderPos = gender.getCheckedRadioButtonId();
    int male = findViewById(R.id.male).getId();
    int female = findViewById(R.id.female).getId();
    String gen;

    if (genderPos == male) 
        gen = "Male";
     else if (genderPos == female) 
        gen = "Female";
     else 
        gen = "Other";
    
    intent.putExtra("gen_key", gen);

    Button theBtn = findViewById(R.id.addAPersonButt);
    theBtn.setOnClickListener(new View.OnClickListener() 
        @Override
        public void onClick(View v) 
            Intent intents = new Intent (MainActivity1.this, MainActivity2.class);
            startActivity(intents);
        
    );

    Button conButt = findViewById(R.id.confirm);
    conButt.setOnClickListener(new View.OnClickListener() 
        @Override
        public void onClick(View v) 
            Intent intent = new Intent(MainActivity1.this, SecondActivity.class);

            EditText name = findViewById(R.id.entName);
            String fullName = name.getText().toString();
            intent.putExtra("name_key", fullName);

            EditText ages = findViewById(R.id.age);
            String age = ages.getText().toString();
            intent.putExtra("age_key", age);

            RadioGroup gender = findViewById(R.id.genRGroup);
            int genderPos = gender.getCheckedRadioButtonId();
            int male = findViewById(R.id.male).getId();
            int female = findViewById(R.id.female).getId();
            String gen;

            if (genderPos == male) 
                gen = "Male";
             else if (genderPos == female) 
                gen = "Female";
             else 
                gen = "Other";
            
            intent.putExtra("gen_key", gen);

            startActivity(intent);
        
    );

【问题讨论】：

name 为空（来自 findViewById），或者.getText() 为空；我敢打赌前者。在链式调用之前添加检查。

【参考方案1】：

它崩溃是因为name.getText() 正在获取空值。在String fullName = name.getText().toString(); 中用if 语句包围

例子：

String fullName;
if(!name.getText().toString().isEmpty())
    fullName = name.getText().toString();

【讨论】：

这种方法不能解决问题。如果name 为null，这种方法仍然会抛出NPE。