Question

我使用if语句限制用户必须在editText中输入电话号码但按下按钮后活动开始的editText事件为空

     et= (EditText) findViewById(R.id.editText1);
    Button b1 = (Button) findViewById(R.id.button1);   
    if (et != null){
    b1.setOnClickListener(new OnClickListener() {
            @Override
        public void onClick(View v) {
            MediaPlayer mp1=        MediaPlayer.create(MainActivity.this,R.raw.button_test);
            mp1.start();

            startActivity(new Intent(MainActivity.this, Register.class));  
            }   
    });      }

Answer 1

你的条件是错误的。试试这个：

if (!et.getText().toString().trim().equals("")){

Answer 2

et不会为null，如果是editText，则会有地址。使用

if(!et.getText().toString().equals(""))

Answer 3

你可以试试这个。

 et= (EditText) findViewById(R.id.editText1);
 Button b1 = (Button) findViewById(R.id.button1); 
 b1.setOnClickListener(new OnClickListener() {
        @Override
    public void onClick(View v) {
    if(et.getText().toString().length!=0){
    MediaPlayer mp1= MediaPlayer.create(MainActivity.this,R.raw.button_test);
        mp1.start();

        startActivity(new Intent(MainActivity.this, Register.class));
        }

     }   
});

Answer 4

et是控件的实例。请在以下代码中使用if

et= (EditText) findViewById(R.id.editText1);
Button b1 = (Button) findViewById(R.id.button1);   

b1.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        if (et.getText() != null && et.getText().toString().length > 0){
            MediaPlayer mp1 = MediaPlayer.create(MainActivity.this,R.raw.button_test);
            mp1.start();
            startActivity(new Intent(MainActivity.this, Register.class));  
        }
    }   
});

IF语句不适用于Android

4 个答案: